Ring of Fire: Memaknai Tektonik Lempeng

Agustus 13, 2018

TEKTONIKKARATE

Tektonik Karate, yang mengilustrasikan pengendali mekanisme tektonik tumbukan di Indonesia Timur

Pendidikan Publik: RING OF FIRE

Sumber: https://pubs.usgs.gov/gip/dynamic/fire.html

https://www.nationalgeographic.org/encyclopedia/ring-fire/

Busur volkani dan parit samudera (Volcanic arcs and oceanic trenches) sebagaian mengelilingi Cekungan Pasifik  yang membentuk apa yang disebut sebagai Cincin Api  (partly encircling the Pacific Basin form the so-called Ring of Fire), suatu zona yang sering mengalami gempabumi dan letusan gunungapi (a zone of frequent earthquakes and volcanic eruptions).

Pada  peta parit-parit dalam ditunjukkan dengan warna biru dan hijau (The trenches are shown in blue-green). Busur-busur kepulauan volkanik walaupunt tidak diberi label, tetapi sejajar, dan selalu pada bagian kearah daratan dari parit-parit (The volcanic island arcs, although not labelled, are parallel to, and always landward of, the trenches). Sebagai contoh busur kepulauan berasosiasi dengan Parit Sunda diprepresentasikan oleh suatu cincin gunung api yang panjang yang menyusun dari pulau-pulau Sumatera-Jawa-NTB.

National Geographic Education

Ring of Fire

Ciri-ciri geologi sepanjang “Cincin Api” termasuk tidak hanya gunungapi, tapi parit samudera, pegunungan parit, kepundan hidrotermal, dan lokasi-lokasi aktivitas gempabumi seperti di Indonesia (Geologic features along the Ring of Fire include not only volcanoes, but ocean trenches, mountain trenches, hydrothermal vents, and sites of earthquake activity). Map courtesy USGS.
Jolting Japan
The island nation of Japan lies along the western edge of the Ring of Fire, and is one of the most tectonically active places on Earth. As much as 10% of the world’s volcanic activity takes place in Japan.
Cooling Ring
The Pacific Plate, which drives much of the tectonic activity in the Ring of Fire, is cooling off. Scientists have discovered that the youngest parts of the Pacific Plate (about 2 million years old) are cooling off and contracting at a faster rate than older parts of the plate (about 100 million years old). The younger parts of the plate are found in its northern and western parts—the most active parts of the Ring of Fire.
The Ring of Fire is a string of volcanoes and sites of seismic activity, or earthquakes, around the edges of the Pacific Ocean. Roughly 90% of all earthquakes occur along the Ring of Fire, and the ring is dotted with 75% of all active volcanoes on Earth.
The Ring of Fire isn’t quite a circular ring. It is shaped more like a 40,000-kilometer (25,000-mile) horseshoe. A string of 452 volcanoes stretches from the southern tip of South America, up along the coast of North America, across the Bering Strait, down through Japan, and into New Zealand. Several active and dormant volcanoes in Antarctica, however, “close” the ring.
  • Plate Boundaries

    The Ring of Fire is the result of plate tectonicsTectonic plates are huge slabs of the Earth’s crust, which fit together like pieces of a puzzle. The plates are not fixed but are constantly moving atop a layer of solid and molten rockcalled the mantle. Sometimes these plates collide, move apart, or slide next to each other. Most tectonic activity in the Ring of Fire occurs in these geologically active zones.
    Convergent Boundaries 
    convergent plate boundary is formed by tectonic plates crashing into each other. Convergent boundaries are often subduction zones, where the heavier plate slips under the lighter plate, creating a deep trench.
    This subduction changes the dense mantle material into buoyant magma, which rises through the crust to the Earth’s surface. Over millions of years, the rising magma creates a series of active volcanoes known as a volcanic arc.
    If you were to drain the water out of the Pacific Ocean, you would see a series of deep ocean trenches that run parallel to corresponding volcanic arcs along the Ring of Fire. These arcs create both islands and continental mountain ranges.
    The Aleutian Islands in the U.S. state of Alaska, for example, run parallel to the Aleutian Trench. Both geographic features continue to form as the Pacific Plate subducts beneath the North American Plate. The Aleutian Trench reaches a maximum depth of 7,679 meters (25,194 feet). The Aleutian Islands have 27 of the United States’ 65 historically active volcanoes.
    The Andes Mountains of South America run parallel to the Peru-Chile Trench, created as the Nazca Plate subducts beneath the South American Plate. The Andes Mountains include the world’s highest active volcano, Nevados Ojos del Salado, which rises to 6,879 meters (over 22,500 feet) along the Chile-Argentina border.
    Many volcanoes in Antarctica are so geologically linked to the South American part of the Ring of Fire that some geologists refer to the region as the “Antarctandes.”
    Divergent Boundaries
    divergent boundary is formed by tectonic plates pulling apart from each other. Divergent boundaries are the site of seafloor spreading and rift valleys. Seafloor spreading is the process of magma welling up in the rift as the old crust pulls itself in opposite directions.
    Cold seawater cools the magma, creating new crust. The upward movement and eventual cooling of this magma has created high ridges on the ocean floor over millions of years.
    The East Pacific Rise is a site of major seafloor spreading in the Ring of Fire. The East Pacific Rise is located on the divergent boundary of the Pacific Plate and the Cocos Plate (west of Central America), the Nazca Plate (west of South America), and the Antarctic Plate. The largest known group of volcanoes on Earth is found underwater along the portion of the East Pacific Rise between the coasts of northern Chile and southern Peru.
    
Transform Boundaries 
    transform boundary is formed as tectonic plates slide horizontally past each other. Parts of these plates get stuck at the places where they touch.
    Stress builds in those areas as the rest of the plates continue to move. This stress causes the rock to break or slip, suddenly lurching the plates forward and causing earthquakes.
    These areas of breakage or slippage are called faults. The majority of Earth’s faults can be found along transform boundaries in the Ring of Fire.
    The San Andreas Fault, stretching along the central west coast of North America, is one of the most active faults on the Ring of Fire. It lies on the transform boundary between the North American Plate, which is moving south, and the Pacific Plate, which is moving north. Measuring about 1,287 kilometers (800 miles) long and 16 kilometers (10 miles) deep, the fault cuts through the western part of the U.S. state of California. Movement along the fault caused the 1906 San Francisco earthquake, which destroyed nearly 500 city blocks. The earthquake and accompanying fires killed roughly 3,000 people and left half of the city’s residents homeless.
    Hot Spots
    The Ring of Fire is also home to hot spots, areas deep within the Earth’s mantle from which heat rises. This heat facilitates the melting of rock in the brittle, upper portion of the mantle. The melted rock, known as magma, often pushes through cracks in the crust to form volcanoes.
    Hot spots are not generally associated with the interaction or movement of Earth’s tectonic plates. For this reason, many geologists do not consider hot spot volcanoes part of the Ring of Fire.
    Mount Erebus, the most southern active volcano on Earth, sits over the eruptive zone of the Erebus hot spot in Antarctica. This glacier-covered volcano has a lava lake at its summit, and has been consistently erupting since it was first discovered in 1841.
    Active Volcanoes in the Ring of Fire
    Most of the active volcanoes on The Ring of Fire are found on its western edge, from the Kamchatka Peninsula in Russia, through the islands of Japan and Southeast Asia, to New Zealand.
    Mount Ruapehu in New Zealand is one of the more active volcanoes in the Ring of Fire, with yearly minor eruptions, and major eruptions occurring about every 50 years. It stands 2,797 meters (9,177 feet) high. Mount Ruapehu is part of the Taupo Volcanic Arc, where the dense Pacific Plate is subducting beneath the Australian Plate.
    Krakatau, perhaps better known as Krakatoa, is an island volcano in Indonesia. Krakatoa erupts less often than Mount Ruapehu, but much more spectacularly. Beneath Krakatoa, the denser Australian Plate is being subducted beneath the Eurasian Plate. An infamous eruption in 1883 destroyed the entire island, sending volcanic gasvolcanic ash, and rocks as high as 80 kilometers (50 miles) in the air. A new island volcano, Anak Krakatau, has been forming with minor eruptions ever since.
    Mount Fuji, Japan’s tallest and most famous mountain, is an active volcano in the Ring of Fire. Mount Fuji last erupted in 1707, but recent earthquake activity in eastern Japan may have put the volcano in a “critical state.” Mount Fuji sits at a “triple junction,” where three tectonic plates (the Amur Plate, Okhotsk Plate, and Philippine Plate) interact.
    The Ring of Fire’s eastern half also has a number of active volcanic areas, including the Aleutian Islands, the Cascade Mountains in the western U.S., the Trans-Mexican Volcanic Belt, and the Andes Mountains.
    Mount St. Helens, in the U.S. state of Washington, is an active volcano in the Cascade Mountains. Below Mount St. Helens, both the Juan de Fuca and Pacific plates are being subducted beneath the North American Plate. Mount St. Helens lies on a particularly weak section of crust, which makes it more prone to eruptions. Its historic 1980 eruption lasted 9 hours and covered nearby areas in tons of volcanic ash.
    Popocatépetl is one of the most dangerous volcanoes in the Ring of Fire. The mountain is one of Mexico’s most active volcanoes, with 15 recorded eruptions since 1519.  The volcano lies on the Trans-Mexican Volcanic Belt, which is the result of the small Cocos Plate subducting beneath the North American Plate. Located close to the urban areas of Mexico City and Puebla, Popocatépetl poses a risk to the more than 20 million people that live close enough to be threatened by a destructive eruption.

 

 

MEMAKNAI TEKTONIK: PERGERAKAN LEMPENG

Agustus 13, 2018

Sumber USGS: https://pubs.usgs.gov/gip/dynamic/understanding.html#anchor19173262

Prolog: Perlunya pendidikan publik terkait pengendali mekanisme Bencana Alam

Pasca terjadinya Bencana alam Gempabumi, Tsunami, Letusan gunungapi, masyarakat menjadi lebih peduli terhadap apa penyebabnya. Dimana dimaknai oleh Konsep Tektonik Lempeng, sebagai Paradigma Baru Tektonik Global, yang mengendalikan mekanisme evolusi bumi termasuk bahaya geologi (Geohazard) yang ditimbulkan. Ditampilkan salah satu situs USGS didedikasikan kepada pendidikan publik.

Ring of Fire

Geologic features along the Ring of Fire include not only volcanoes, but ocean trenches, mountain trenches, hydrothermal vents, and sites of earthquake activity.

Map courtesy USGS.

 

Hardi

Memaknai pergerakan lempeng Understanding plate motion

Scientists now have a fairly good understanding of how the plates move and how such movements relate to earthquake activity. Most movement occurs along narrow zones between plates where the results of plate-tectonic forces are most evident.

There are four types of plate boundaries:

  • Divergent boundaries — where new crust is generated as the plates pull away from each other.
  • Convergent boundaries — where crust is destroyed as one plate dives under another.
  • Transform boundaries — where crust is neither produced nor destroyed as the plates slide horizontally past each other.
  • Plate boundary zones — broad belts in which boundaries are not well defined and the effects of plate interaction are unclear.
 Illustration of the Main Types of Plate Boundaries [55 k]

Batas-batas divergen Divergent boundaries

Divergent boundaries occur along spreading centers where plates are moving apart and new crust is created by magma pushing up from the mantle. Picture two giant conveyor belts, facing each other but slowly moving in opposite directions as they transport newly formed oceanic crust away from the ridge crest.

Perhaps the best known of the divergent boundaries is the Mid-Atlantic Ridge. This submerged mountain range, which extends from the Arctic Ocean to beyond the southern tip of Africa, is but one segment of the global mid-ocean ridge system that encircles the Earth. The rate of spreading along the Mid-Atlantic Ridge averages about 2.5 centimeters per year (cm/yr), or 25 km in a million years. This rate may seem slow by human standards, but because this process has been going on for millions of years, it has resulted in plate movement of thousands of kilometers. Seafloor spreading over the past 100 to 200 million years has caused the Atlantic Ocean to grow from a tiny inlet of water between the continents of Europe, Africa, and the Americas into the vast ocean that exists today.

Mid-Atlantic Ridge gif Mid-Atlantic Ridge [26 k]

The volcanic country of Iceland, which straddles the Mid-Atlantic Ridge, offers scientists a natural laboratory for studying on land the processes also occurring along the submerged parts of a spreading ridge. Iceland is splitting along the spreading center between the North American and Eurasian Plates, as North America moves westward relative to Eurasia.

Map showing the Mid-Atlantic Ridge splitting Iceland and separating the North American and Eurasian Plates. The map also shows Reykjavik, the capital of Iceland, the Thingvellir area, and the locations of some of Iceland’s active volcanoes (red triangles), including Krafla.

The consequences of plate movement are easy to see around Krafla Volcano, in the northeastern part of Iceland. Here, existing ground cracks have widened and new ones appear every few months. From 1975 to 1984, numerous episodes of rifting (surface cracking) took place along the Krafla fissure zone. Some of these rifting events were accompanied by volcanic activity; the ground would gradually rise 1-2 m before abruptly dropping, signaling an impending eruption. Between 1975 and 1984, the displacements caused by rifting totaled about 7 m.

lava fountains gif Lava Fountains, Krafla Volcano [35 k]

Thingvellir fissure zone gif Thingvellir Fissure Zone, Iceland [80 k]

In East Africa, spreading processes have already torn Saudi Arabia away from the rest of the African continent, forming the Red Sea. The actively splitting African Plate and the Arabian Plate meet in what geologists call a triple junction, where the Red Sea meets the Gulf of Aden. A new spreading center may be developing under Africa along the East African Rift Zone. When the continental crust stretches beyond its limits, tension cracks begin to appear on the Earth’s surface. Magma rises and squeezes through the widening cracks, sometimes to erupt and form volcanoes. The rising magma, whether or not it erupts, puts more pressure on the crust to produce additional fractures and, ultimately, the rift zone.

East Africa volcanoes gif Historically Active Volcanoes, East Africa [38 k]

East Africa may be the site of the Earth’s next major ocean. Plate interactions in the region provide scientists an opportunity to study first hand how the Atlantic may have begun to form about 200 million years ago. Geologists believe that, if spreading continues, the three plates that meet at the edge of the present-day African continent will separate completely, allowing the Indian Ocean to flood the area and making the easternmost corner of Africa (the Horn of Africa) a large island.

 Summit Crater of ‘Erta ‘Ale [55 k]

Oldoinyo erupts gif Oldoinyo Lengai, East African Rift Zone [38 k]

Batas-batas konvergen : Convergent boundaries

The size of the Earth has not changed significantly during the past 600 million years, and very likely not since shortly after its formation 4.6 billion years ago. The Earth’s unchanging size implies that the crust must be destroyed at about the same rate as it is being created, as Harry Hess surmised. Such destruction (recycling) of crust takes place along convergent boundaries where plates are moving toward each other, and sometimes one plate sinks (is subducted) under another. The location where sinking of a plate occurs is called a subduction zone.

The type of convergence — called by some a very slow “collision” — that takes place between plates depends on the kind of lithosphere involved. Convergence can occur between an oceanic and a largely continental plate, or between two largely oceanic plates, or between two largely continental plates.

Konvergen Oseanik-Kontinen: Oceanic-continental convergence

If by magic we could pull a plug and drain the Pacific Ocean, we would see a most amazing sight — a number of long narrow, curving trenches thousands of kilometers long and 8 to 10 km deep cutting into the ocean floor. Trenches are the deepest parts of the ocean floor and are created by subduction.

Off the coast of South America along the Peru-Chile trench, the oceanic Nazca Plate is pushing into and being subducted under the continental part of the South American Plate. In turn, the overriding South American Plate is being lifted up, creating the towering Andes mountains, the backbone of the continent. Strong, destructive earthquakes and the rapid uplift of mountain ranges are common in this region. Even though the Nazca Plate as a whole is sinking smoothly and continuously into the trench, the deepest part of the subducting plate breaks into smaller pieces that become locked in place for long periods of time before suddenly moving to generate large earthquakes. Such earthquakes are often accompanied by uplift of the land by as much as a few meters.

Nazca-SoAm gif Convergence of the Nazca and South American Plates [65 k]

On 9 June 1994, a magnitude-8.3 earthquake struck about 320 km northeast of La Paz, Bolivia, at a depth of 636 km. This earthquake, within the subduction zone between the Nazca Plate and the South American Plate, was one of deepest and largest subduction earthquakes recorded in South America. Fortunately, even though this powerful earthquake was felt as far away as Minnesota and Toronto, Canada, it caused no major damage because of its great depth.

 Ring of Fire [76 k]

Oceanic-continental convergence also sustains many of the Earth’s active volcanoes, such as those in the Andes and the Cascade Range in the Pacific Northwest. The eruptive activity is clearly associated with subduction, but scientists vigorously debate the possible sources of magma: Is magma generated by the partial melting of the subducted oceanic slab, or the overlying continental lithosphere, or both?

Konvergensi Oseanik-Oseanik: Oceanic-oceanic convergence

As with oceanic-continental convergence, when two oceanic plates converge, one is usually subducted under the other, and in the process, a trench is formed. The Marianas Trench (paralleling the Mariana Islands), for example, marks where the fast-moving Pacific Plate converges against the slower moving Philippine Plate. The Challenger Deep, at the southern end of the Marianas Trench, plunges deeper into the Earth’s interior (nearly 11,000 m) than Mount Everest, the world’s tallest mountain, rises above sea level (about 8,854 m).

Subduction processes in oceanic-oceanic plate convergence also result in the formation of volcanoes. Over millions of years, the erupted lava and volcanic debris pile up on the ocean floor until a submarine volcano rises above sea level to form an island volcano. Such volcanoes are typically strung out in chains called island arcs. As the name implies, volcanic island arcs, which closely parallel the trenches, are generally curved. The trenches are the key to understanding how island arcs such as the Marianas and the Aleutian Islands have formed and why they experience numerous strong earthquakes. Magmas that form island arcs are produced by the partial melting of the descending plate and/or the overlying oceanic lithosphere. The descending plate also provides a source of stress as the two plates interact, leading to frequent moderate to strong earthquakes.

Konvergen Kontinen-Kontinen:Continental-continental convergence

The Himalayan mountain range dramatically demonstrates one of the most visible and spectacular consequences of plate tectonics. When two continents meet head-on, neither is subducted because the continental rocks are relatively light and, like two colliding icebergs, resist downward motion. Instead, the crust tends to buckle and be pushed upward or sideways. The collision of India into Asia 50 million years ago caused the Indian and Eurasian Plates to crumple up along the collision zone. After the collision, the slow continuous convergence of these two plates over millions of years pushed up the Himalayas and the Tibetan Plateau to their present heights. Most of this growth occurred during the past 10 million years. The Himalayas, towering as high as 8,854 m above sea level, form the highest continental mountains in the world. Moreover, the neighboring Tibetan Plateau, at an average elevation of about 4,600 m, is higher than all the peaks in the Alps except for Mont Blanc and Monte Rosa, and is well above the summits of most mountains in the United States.

Above: The collision between the Indian and Eurasian plates has pushed up the Himalayas and the Tibetan Plateau. Below: Cartoon cross sections showing the meeting of these two plates before and after their collision. The reference points (small squares) show the amount of uplift of an imaginary point in the Earth’s crust during this mountain-building process.

Batas-batas Transform: Transform boundaries

The zone between two plates sliding horizontally past one another is called a transform-fault boundary, or simply a transform boundary. The concept of transform faults originated with Canadian geophysicist J. Tuzo Wilson, who proposed that these large faults or fracture zones connect two spreading centers (divergent plate boundaries) or, less commonly, trenches (convergent plate boundaries). Most transform faults are found on the ocean floor. They commonly offset the active spreading ridges, producing zig-zag plate margins, and are generally defined by shallow earthquakes. However, a few occur on land, for example the San Andreas fault zone in California. This transform fault connects the East Pacific Rise, a divergent boundary to the south, with the South Gorda — Juan de Fuca — Explorer Ridge, another divergent boundary to the north.

The Blanco, Mendocino, Murray, and Molokai fracture zones are some of the many fracture zones (transform faults) that scar the ocean floor and offset ridges (see text). The San Andreas is one of the few transform faults exposed on land.

The San Andreas fault zone, which is about 1,300 km long and in places tens of kilometers wide, slices through two thirds of the length of California. Along it, the Pacific Plate has been grinding horizontally past the North American Plate for 10 million years, at an average rate of about 5 cm/yr. Land on the west side of the fault zone (on the Pacific Plate) is moving in a northwesterly direction relative to the land on the east side of the fault zone (on the North American Plate).

San Andreas gif San Andreas fault [52 k]

Oceanic fracture zones are ocean-floor valleys that horizontally offset spreading ridges; some of these zones are hundreds to thousands of kilometers long and as much as 8 km deep. Examples of these large scars include the Clarion, Molokai, and Pioneer fracture zones in the Northeast Pacific off the coast of California and Mexico. These zones are presently inactive, but the offsets of the patterns of magnetic striping provide evidence of their previous transform-fault activity.

Zona-Zona Batas Lempeng: Plate-boundary zones

Not all plate boundaries are as simple as the main types discussed above. In some regions, the boundaries are not well defined because the plate-movement deformation occurring there extends over a broad belt (called a plate-boundary zone). One of these zones marks the Mediterranean-Alpine region between the Eurasian and African Plates, within which several smaller fragments of plates (microplates) have been recognized. Because plate-boundary zones involve at least two large plates and one or more microplates caught up between them, they tend to have complicated geological structures and earthquake patterns.

Kecepatan Gerakan: Rates of motion

We can measure how fast tectonic plates are moving today, but how do scientists know what the rates of plate movement have been over geologic time? The oceans hold one of the key pieces to the puzzle. Because the ocean-floor magnetic striping records the flip-flops in the Earth’s magnetic field, scientists, knowing the approximate duration of the reversal, can calculate the average rate of plate movement during a given time span. These average rates of plate separations can range widely. The Arctic Ridge has the slowest rate (less than 2.5 cm/yr), and the East Pacific Rise near Easter Island, in the South Pacific about 3,400 km west of Chile, has the fastest rate (more than 15 cm/yr).

monolith gif Easter Island monolith [80 k]

Evidence of past rates of plate movement also can be obtained from geologic mapping studies. If a rock formation of known age — with distinctive composition, structure, or fossils — mapped on one side of a plate boundary can be matched with the same formation on the other side of the boundary, then measuring the distance that the formation has been offset can give an estimate of the average rate of plate motion. This simple but effective technique has been used to determine the rates of plate motion at divergent boundaries, for example the Mid-Atlantic Ridge, and transform boundaries, such as the San Andreas Fault.

GPS satellite gif GPS Satellite and Ground Receiver [63 k]

Current plate movement can be tracked directly by means of ground-based or space-based geodetic measurements; geodesy is the science of the size and shape of the Earth. Ground-based measurements are taken with conventional but very precise ground-surveying techniques, using laser-electronic instruments. However, because plate motions are global in scale, they are best measured by satellite-based methods. The late 1970s witnessed the rapid growth of space geodesy, a term applied to space-based techniques for taking precise, repeated measurements of carefully chosen points on the Earth’s surface separated by hundreds to thousands of kilometers. The three most commonly used space-geodetic techniques — very long baseline interferometry (VLBI), satellite laser ranging (SLR), and the Global Positioning System (GPS) — are based on technologies developed for military and aerospace research, notably radio astronomy and satellite tracking.

Among the three techniques, to date the GPS has been the most useful for studying the Earth’s crustal movements. Twenty-one satellites are currently in orbit 20,000 km above the Earth as part of the NavStar system of the U.S. Department of Defense. These satellites continuously transmit radio signals back to Earth. To determine its precise position on Earth (longitude, latitude, elevation), each GPS ground site must simultaneously receive signals from at least four satellites, recording the exact time and location of each satellite when its signal was received. By repeatedly measuring distances between specific points, geologists can determine if there has been active movement along faults or between plates. The separations between GPS sites are already being measured regularly around the Pacific basin. By monitoring the interaction between the Pacific Plate and the surrounding, largely continental plates, scientists hope to learn more about the events building up to earthquakes and volcanic eruptions in the circum-Pacific Ring of Fire. Space-geodetic data have already confirmed that the rates and direction of plate movement, averaged over several years, compare well with rates and direction of plate movement averaged over millions of years.

Prasetyo 2018 Mengikuti Ceramah Imajiner GEO LUSI di Oslo University

Juli 26, 2018

BAGIAN 1: MENANGKAP ISU AKTUAL

GEOLUSI-VIDEO

Testimoni LUSI (Lumpur Sidoarjo) mendapatkan Perhatian yang luar biasa dari barbagai kalangan baik di dalam dan di mancanegara. 25 Agustus 2015 Presiden Joko Widodo mengunjungi Lusi. Sebelumnya mantan Presiden RI Soesilo Bambang Yudhoyono 2007 dan 2010 telah melakukan Kunjungan Kerja ke LUSI.

Mengikuti Ceramah secara imajiner di Oslo University, Norwey

  GEO RABU: SEMBURAN LUSI 

Sumber Youtube “GEO Wednesday: The Lusi eruption”

Pembicara  tunggal Adriano Mazzini, dari “Centre for Earth Evolution and Dynamics (CEED), UiO”, Maret 7, 2018, The Science Library, Vilhelm Bjerknes’ hus

Dikontribusikan oleh: Hardi Pasetyo

Mantan Pimpinan BPLS (2007-2017), Inisiator “Science Manager” melalui LUSI LIBRARY:KNOWLEDGE MANAGEMENT 2010-2017, MENJADADI “Geyser Lusi Library and Virtual Museum 2018”

Tradisi “Mengikuti dan Evaluasi Ceramah Imajiner”, Terbaru 2018 dari Kampus Oslo University – LUSI-LAB merupakan hasil kerjasama dengan BPLS 2012-2017 akan lanjut 2018 ke PPLS (Institusi baru dibawah Ditjen SDA, Kementrian PUPR).

ALBUM: BAGIAN 1 RESUME DAN HASIL PENTING

 Beberapa Isu telah di elaborasi dan evaluasi selanjutnya ditempatkan pada BlOG Geyser Lusi Library&Virtual Museum 2018.

Foto Hardi Prasetyo.

ISU AKTUAL LUSI SECARA KESELURUHAN DAN KHUSUSNYA DARI PROGRAM LUSI LAB (KONSORSIUM INSTITUSI KEBUMIAN DARI MASYARAKAT EROPA) YANG TELAH BEKERJAAMA DENGAN BPLS 2012-2017

Terus diikuti, sebagai tindak lanjut kebijakan “Upaya Penanggulangan Lusi, dengan mengalirkan Lusi melalui Tanggul Utama ke Kali Porong, membangun Infrastruktur penahan luapan lumpur, serta Langkah Mitigasi untuk melindungi masyarakat di sekitarnya”.
Telah diposting pada berbagai BLOG total ~1000 (termasuk BlogSpot, SiteGoogle, Youtube, dan lain-lain).
Pokok Studi dari Program LUSI LAB, Multi Disiplin merupakan Interaksi dari:
1) KEGEMPAAN (SEISMICITY);
2) KEGUNUNGAPIAN (VOLCANOLOGY)
3) ALIRAN FLUIDA (FLUID FLOWS), SISTEM HIDROTERMAL DALAM (DEEP HYDROTERMAL SYSTEM);
4) REAKTIVASI PATAHAN WATUKOSEK (WATUKOSEK FAULT REACTIVATION);
5) BERBAGAI PEMODELAN (MODELLING).

Foto Hardi Prasetyo.Poster pada Ceramah THE LUSI ERUPTION,
Andriiano Mazzini, LUSI LAB, 7 Maret 2018, baru dirilis beberapa hari lalu.

Suasana pembukaan Ceramah dengan pembicara tunggal Dr. Andriano Mazzini;Foto Hardi Prasetyo.

Dr. Andriano Mazzini, membuka ceramah “GEO:SEMBURAN LUSI’ dengan foto yang memperlihatkan Postur Lusi mud volcano, dan bagian penting di latar belakang (selatan) terdapat Gugusan Gunung magmatik Arjuno-Welirang-Penanggungan, dan diantaranya di selatan Kali Porong adalah Gawir Watukosek (Watukosek Escarpment).

Diawali dengan Misteri dengan Struktur Piercement (Pembubungan): Kepentingan dan Kemanfaatannya;

Foto Hardi Prasetyo.

Ceramah dibuka Maksud dan Tujuan, Kemanfaatan dan Hasil Signifikan dari LUSI LAB.
Selanjutnya memasuki bagian teknis dengan lebih dahulu memperkenalkan Misteri Struktur Pembubungan (Piercement Structure).
KEPENTINGAN
EKONOMI:Eksplorasi Migas, Air Tanah, Sumber Daya Mineral, Eksplorasi Migas dan Air Tanah, dan Sumber Daya Mineral;
ILMIAH: Transpor gas ke atmosfer (Iklim Modern-Purba), Penyelidikan “Early life”.
SOSIAL: Bahaya Geologi (Geohazard); Sumberdaya Air Tanah.
KEPENTINGAN UNTUK PENELITIAN
Mekanisme dan reaksi yang masih belum jelas.
Saat ini umumnya dipelajari dari sistem-sistem purba (paleo system) atau telah dormant.
Upaya-upaya pemodelan sering tidak berhasil, tidak adanya parameter pembatas.
Penampilan dari Bahaya Geologi (Geohazard).

Model Ideal mud volcano di Cekungan Caspia, didominasi mengeluarkan gas metan CH4.

Foto Hardi Prasetyo.

  • Pengendapan sedimen kaya dengan material organik
  • Amblesan (Subsidence) dan penguburan cepat
  • Satuan tidak terkompaksi (Undercompaction), secara gayaberat tidak stabil
  • Menghasilkan fluida kaya HC
  • Ilitisasi lempung + rekahan hidro
  • Pembentukan struktur mud volcano berkaitan dengan reservoir minyak bumi

Sistem hidrotermal dikendalikan oleh hubungan magmatik terutama menghasilkan gas CO2;

Foto Hardi Prasetyo.

  • SISTEM HIDROTERMAL mengeluarkan gas CO2
    Pemindahan magmatik pada kedalaman.
    Gradien geotermal yang tinggi.
    Berkembang baik sebagai aliran fluida yang besar dan sel-sel konveksi.
    Terjadi Interaksi antara air meteorik dan fluida magmatik.

3 Tipe sistem Piercement:

1) Sistem Hidrotermal, Geyser Yellow Stone, National Park, USA; 2) Mud volcano, sebagai volkanisme sedimen, Cekungan Caspia; 3) HIBRIDA: Induk sedimen sistem hidrotermal, Lusi, dan Salton Sea dll.

Foto Hardi Prasetyo.
@Sistem Hidrotermal, berhubungan dengan fenomena gunung api ataiu magmatisme (seperti di Yellow Stone National Park), Dr. Mazzini pada ceramah menekankan bahwa Yellow Stone bukan merupakan mud volcano.
@ Mud volcano yang konvensional, sebagai hasil dari volkanisme sedimen (sedimentary volcanism), contoh ideal adalah di Cekungan Caspia, Azerbeijan.
@ HIBRIDA dua sistem di atas, yaitu “INDUK-SEDIMEN SISTEM HIDROTERMAL” (SEDIMENT-HOSTED HYDROTHERMAL SYSTEM). Merupakan tipe dari Geyser Lusi, juga Salton Sea di Califormia.

Pemahaman awal 2006-2010 Lusi sebagai suatu mud volcano yang konvensional, sejak 2011 (pada Simposium Ilmiah Internasional Lusi dilaksanakan bersama BPLS dan HSF Australia) dideklarasikan Lusi sistem hidrotermal dalam (the deep hydrothermal system) berhubungan dengan gunung magmatik;

Hasil Signifikan LUSI-LAB bekerjasama dengan BPLS melalui pendekatan Penelitian multidisiplin:

Foto Hardi Prasetyo.

PROGRAM LUSI LAB bekerjasama dengan BPLS 2012-2017, merupakan kegiatan penelitian Ilmiah secara komprehensif, integral yang melibatkan banyak Institusi Kebumian di Eropa, menerapkan berbagai disiplin, termasuk merancang wahana Drone Lusi (dimana bisa mengambil contoh fluida dan lumpur di kawan dan merekam Inframerah). Disamping itu saat ini merancang peralatan pengambilan contoh langsung di kawah Lusi dengan Robot, dan penerapan teknologi Seismik Tomografi dengan rasio kesulitan yang tinggi (baru pertama kalinya diterapkan di Lusi dan gunungapi di selatannya).

Hasil LUSI Drone, citra Inframerah ditumpangsusunkan dengan Pita Citra Google Earth, dan Pemodelan plume fluida di Kawah Lusi. 

Studi dengan Seismik tomografi dihasilkan LUSI LAB sebagai “senjata pamungkas” membuktikan hubungan Lusi dengan gunung magmatik. Gambar merupakan bagian Presentasi di PPLS akhir Desember 2017. 

MELUNCURKAN GEYSER LUSI LIBRARY -VIRTUAL MUSEUM 2018, HIDUP HARMONI

Hasil Publikasi Ilmiah pada Jurnal Internasional, 22 makalah terbaru 2018 diterbitkan pada Edisi Khusus The Marine Petroleum GeoLogy (MPG) 2018.
Lainnya pada Puluhan Paper Presentasi dan Poster di Pertemuan Tahunan EGU 2016-2018. Telah dievaluasi dan dikaji, diposting pada Blog Geyser Lusi library&Virtual Museum;

HASIL ISU AKTUAL:

 PEMODELAN MIGRASI FLUIDA DI CEKUNGAN BUSUR BELAKANG, APAKAH AKAN TERJADI PEMBENTUKAN GUNUNGAPI BARU?

Foto Hardi Prasetyo.

Hasil seismik tomografi mengkonfirmasi hubungan Lusi dengan kantong magma (magma chamber) dari gunung Penanggungan dan diindikasikan di bawah Lusi terdapat “Hidrotermal Plume”.

Memberikan implikasi Geohazard, bahwa panjang umur semburan geyser Lusi akan panjang? Sebagaimana yang telah dimodelkan dengan beberapa pendekatan sebelumnya.

Contoh salah satu hasil penentuan panjang umur semburan Lusi oleh Prof. Richard Davies (Durham University, UK), dipresentasikan pada even Simposium Ilmiah Internasional Lusi 2011, berdasarkan sumber air di reservoir, menghasilkan 26 Tahun. Sebagai implikasi Geohazard, bila kecepatan amblesan stabil 4cm/hari maka total 26 tahun 475 meter.

Disamping itu Isu Aktual lainnya adalah apakah akan/dapat terjadi berpropagasi gunungapi ke utara? Sebagaimana yang telah dikeluarkan Press Release oleh American Geophysical Union (AGU Oktober 2017).

 FAKTA LAPANGAN:

Foto Hardi Prasetyo.

BAGAIMANA NASIP DARI BUSUR VOLKANIK SELANJUTNYA KE DEPAN?
KIRI:
Patahan Watukosek sebagai induk mud volcano lainnya di Jawa Timur.
Apakah patahan pengrontrol evolusi dari busur volkanik?
KANAN:
Ciri-ciri Geologi sangat jelas mengindikasikan keberadaan Patahan.

Posisi gunung Arjuno-Welirang-Penanggungan berpropagasi ke utara (timurlaut). Keberadaan Patahan Watukosek di bagian selatan sangat jelas.
Pertanyaan dan Isu Kritis apakah Patahan Watukosek akan mengendalikan busur magmatik ke utara, yang diasumsikan melalui jalur Lusi yang telah dicirikan dengan “hidrothermal plume”?

Foto Hardi Prasetyo.

KEMAJUAN PENERAPAN IPTEK KEBUMIAN (Seismik Tomografi, Seismik 2 D dan Rencana Seismik 3D).
Untuk mendukung rencana Studi Bawah Pemukaan Lusi secara komprehensif dan Integral. Sebagai alat bantu proses pengambilan Kebijakan Pengurangan Risiko Bencana Kedepan. (Prasetyo 2016).
Seismik Tomograsi: Memperkuat pembuktian hubungan Lusi dengan kantong magma dari gunung magmatik di selatannya. Juga suatu perkiraan/Indikasi Geohazard terjadinya fenomena “PROPAGASI SISTEM GUNUNGAPI DI BUSURDEPAN (FOREARC) KE BUSUR BELAKANG (BACKARC) MELALUI LINTASAN KEARAH LUSI”?.
Dengan temuan baru bahwa di bawah Lusi telah diketemukan “Plume Hydrothermal” sehingga memperkuat perkiraan bahwa panjang umur semburan geyser Lusi akan panjang, karena telah dipengaruhi oleh faktor tekonik regional (regional tectonic) di busur depan Sunda (Sunda forearc region).
Hasil Studi Seismik Refleksi 2D, memperbarui tatanan seismik stratigrafi di bawah Lusi. Disamping itu memperjelas keberadaan Sistem Patahan-geser Watukosek (Watukosek strike-slip fault) di bawah permukaan yang diperkirakan sampai ke dekat permukaan?
Disamping isu aktual yang perlu dielaborasi adalah hasil Tim Rusia dengan teknik GIS 3D, dimana telah menemukan 2 struktur lumpur (mud structure), dimaknai sebagai struktur pembubungan (piercement structure) yang purba (paleo), namun dari aspek Geohazard bila dipicu gempabumi yang memadai bisa berkembang menjadi mud volcano seperti Lusi?

Hasil misi “FROM RUSSIAN WITH LUSI 2010” saya seolah-oleh “dikeroyak oleh para ahli Kebumian di Moscow”, sebagai oleh-oleh mendapatkan dokumen hasil studi Tim Kebumian Rusia untuk LUSI.

PATAHAN WATUKOSEK disarikan dari MPG 2018, dipresentasikan di PPLS Desember 2017;

Foto Hardi Prasetyo.

ISU AKTUAL LUSI:
LUSI DIHUBUNGKAN DENGAN GUNUNG MAGMATIK OLEH SISTEM PATAHAN WATUKOSEK.
Yang berawal di utara dari Gunung Penanggungan, merupakan gunung magmatik paling depan dari busurdepan Sunda.
Ditafsirkan  secara Tektonik Regional bahwa telah terjadi propagasi busur “propagation Arc” dengan majunya Gunung Api Arjuno-Welirang-Penanggungan (dari tua ke muda) dengan liniasi timurlaut-baratdaya, dikendalikan oleh keberadaan Patahan Geser Regional Watukosek (RegionalWatukosek strike-slip fault).
Keberadaan Gawir Watukosek dengan “slicken side”, yang bersamaan telah terjadinya pembelokan secara tiba-tiba dari Kali Porong  di zona depan dari Gawir Watukosek (Watukosek Escarpment), dimana pada Doktrin Ilmu Geologi Dasar merupakan indikasi yang standar bagi keberadaan suatu deformasi patahan.

EPILOG: PARADIGMA BARU “HIDUP HARMONI DENGAN BENCANA LUSI”
Sementara para ahli kebumian di dunia disamping masih dibayangi oleh Kontroversi Pemicu semburan Lusi antara Pemboran versus Gempabumi, juga terus mengungkapkan indikasi GeoHazard Lusi.
Disisi lain sejak tahun 2010 diawali di Museum Sidney, Australia (even Pemutaran film dokumenter MUD MAX LUSI) dimana saya (BPLS)  memimpin delegasi Indonesia diperkuat oleh Kementrian Pariwisata, dimana Lusi telah mulai diperkenalkan ke depan akan diusulkanmenjadi suatu Taman Bumi (Geopark) dengan mengedepankan GeoWisata (Geotourism), dimana dalam perjalanan waktu  juga telah ditetapkan oleh Badan Geologi, Kementrian ESDM sebagai SALAH SATU DARI DUABELAS WARISANGEOLOGI (GEOHERITAGE) DI PULAU JAWA.

Foto memperlihatkan Para Srikandi yang mempertontonkan paradigma baru Hidup Harmoni dengan Bencana. Dengan mengedepankan Budaya dan Kearifan lokal “BANGGA BERKEBAYA DI GEYSER LUSI YANG INDAH NAMUN MASIH BERTENAGA”. https://hardiprasetyolusi.wordpress.com/2017/12/27/komprehensif-integral-holistik-penanganan-bencana-lusi-2006-2017/

Prof. Dr. Bambang Tjahyadi, Gurubesar dari Universitas Erlangga (UNAIR), sebagai pembina/penasehat “Komunitas Bangga Berkebaya, Surabaya” secara berkelanjutan mendukung paradigma Hidup Harmoni dengan Bencana, usulan Lusi GeoPark.
Rangkuman Evaluasi Geyser Lusi 2018 (~100 gambar komprehensif) merupakan bagian Memperkokoh LUSI YANG TELAH DITETAPKAN SEBAGAI GEOHERITAGE (WARISAN GEOLOGI) oleh Badan Geologi, KESDM, Sedangkan Pilar CULTUREHERITAGE dan BIOHERITAGE pada batas minimal telah dapat dilengkapi.
POSISI LUSI YANG SANGAT DIKENAL DI SELURUH DUNIA, DIPERKOKOH DENGAN PENETAPAN “LUSI LABORATORIUM ALAM DAN PUSAT UNGGULAN STUDI MUD VOLCANO DIDUNIA’. 

Sebagai dasar yang stratesis, sehingga Tim Satgas GeoPark Indonesia, pada November 2015, melalui even FGD di BPLS, telah menetapkan dari proses Bottom-up bahwa Lusi layak untuk diusulkan sebagai suatu GeoPark, dan ditindaklanjuti dengan Peluncuran TIM KECIL PERCEPATAN PENGEMBANGAN GEOPARK LUSI (22 Desember 2016), dilanjutkan dengan Peresmian EMBRIO MUSEUM GEOPARK LUSI, dengan disaksikan oleh Kepala Museum Geologi, KESDM dan Para Ahli GeoPark Indonesia, serta stakeholders Tim Percepatan Geopark Lusi.

Slide22

23 Desember 2016, Peresmian Embrio Museum GeoPark Lusi, antara lain dihadiri oleh Pak Oman Abdurahman, Kepala Museum Geologi KESDM,  Prof. Dr. Mega Rosana (UNPAD) dan Dr. Heryadi Rachmat juga atas dukungan Pak Rudy Suhendar (Sekarang Kepala Badan Geologi, KESDM).

Foto Hardi Prasetyo.

DENGAN MENGEMBANGKAN “BIKE TO WORK LUSI B2Wl” SEJAK 2010 TERUS MEMANTAU DENGAN SELANG WAKTU PENDEK, TERHADAP POSTUR DAN PERILAKU GEYSER LUSI YANG SANGAT DINAMISSehingga perubahan sekecil apapun dapat diikut dan direkam.

Satu-satunya di Dunia Pada Misi Nasional Penanggulangan Bencana Kebumian Lusi telah dikembngkan Sistem MONEV dan WASDAL Bike to Work Lusi. Hasilnya Luar biasa, rekaman time series dinamika Lusi diintegrasikan dengan Evolusi Citra Penginderaan Jauh (Satelit, Helikopter dan Drone).

Foto Hardi Prasetyo.

TRANSISI DARI LUSI LIBRARY:KNOWLEDGE MANAGEMENT (2010-2017) MENUJU 2018 GEYSER LUSI LIBRARY & VIRTUAL MUSEUM.
Salah satu Koleksi yang dinilai Paling lengkap mengikuti Knonologi Sejarah Misi Nasional Penanggulangan Bencana Lusi. Termasuk Evolusi “DARI SUATU SEMBURAN GANAS YANG MERUSAK SEHINGGA MENIMBULKAN 14 PAHLAWAN LUSI, SAMPAI PETA JALAN MENGUSULKAN LUSI SEBAGAI GEOPARK MENGEDEPANKAN GEOWISATA”.

Maret 2017, saya selaku Pimpinan BPLS dan saat itu Koordinator Tim Kecil Pengembangan GeoPark Lusi telah diberi kehormatan dari Pemda Provinsi Jatim, memaparkan “PESONA GEOWISATA MENUJU GEOPARK LUSI”, pada even Promosi Pariwisata Terbesar di Kawasan Timur Indonesia.
Sedangkan Pilar GeoHeritage diperkokoh dengan telah dideklarasikan pada 9 Oktober 2015 bersama FITB ITB dan lain-lain suatu Paradigma ke depan ‘LUSI SEBAGAI LABORATORIUM ALAM, PUSAT STUDI MUD VOLCANO DI DUNIA’.
~ 22 Publikasi dari LUSI LAB yang telah diterbitkan tahun 2018 pada Jurnal Internasional telah semakin memperkokoh TESTINOMI BAHWA LUSI TERUS MENJADI PERHATIAN DUNIA, DISAMPING PENGENDALI MEKANISME SEMBURANNYA MASIH BELUM DAPAT DITUNTASKAN ANTARA ALAMI-GEMPABUMI DAN NON-ALAMI-PEMBORAN.
Disamping itu Kajian Ilmu Kebumian di Lusi telah mengindikasikan GeoHazard, sehingga sangat rasional untuk terus dilakukan langkah MITIGASI BENCANA, UNTUK PENGURANGAN RISIKO BENCANA.
BERSAMAAN DENGAN INDIKASI GEOHAZARD JUGA KE DEPAN DIKEMBANGKAN PEMANFAATAN LUSI SELUAS-LUASNYA SECARA BERKELANJUTAN (SUSTAINABLE).

Posting ini juga menampilkan  upaya merajut Kerjasama Ilmiah Antar Kampus Ilmu Kebumian di dalam dan luar negeri, untuk bersama-sama ikut berperan paradigma “Dari Bencana Lusi menuju Kemanfaatan, Hidup Harmoni dengan Bencana Lusi yang masih/dapat berlangsung lama”.

SILAHKAN IKUTI SELENGKAPNYA DI BLOG GEYSER LUSI LIBRARY DAN VIRTUAL MUSEUM? Salam Hormat Hardi Prasetyo

Juli 2018 Dinamika Postur Lusi: Indikasi Geohazard, Langkah Mitigasi Bencana

Juli 14, 2018

                    Dari Citra Satelit dan Helikopter (2004-2009), Infra Merah (2015),                          sampai Citra Drone (Januari – Juli 2018):

Dinamika Postur Lusi, indikasi Geohazard, langkah Mitigasi Bencana

Dikontribusikan Oleh: Hardi Prasestyo 2018,

10 Tahun Mengasuh LUSI (2007-2017)

 

 

Dinamika Postur Lusi JANUARI – JULI 2018 : Evaluasi  Langkah Mitigasi – Indikasi Geohazard Untuk Pengurangan Risiko Bencana
Berdasarkan Citra Drone (Pilot Adang PPLS)

KLIK: YOUTUBE

Dari CitraSatelit dan Helikopter (2004-2009), Infra Merah (2015),
Sampai Citra Drone (Januari – Juli 2018): 

Dinamika Postur Lusiindikasi Geohazardlangkah Mitigasi Bencana

Dikontribusikan Oleh: HardiPrasestyo 2018,10 Tahun Mengasuh
LUSI (2007-2017)

Bahaya geologi LUSI, Pada Edisi Khusus GSL 2017 “Geohazard di Indonesia: Ilmu Kebumian untuk Pengurangan Risiko Bencana”

Antara Pengendali dan Penanggulangan Bencana Lusi 2006-2017 yang Unik, Komplek dan  Bersiklus dengan pola “Spiral”: Tanggap & Pasca Darurat –Pencegahan & Migigasi Bencana

Kartun Model Penafsiran dari IR:  Aliran konvektif di Kawah warna kuning yang paling panas.  Citra IR Drone di tumpangkan diatas citra Satelit Google Earth. Foto Kawah.

Citra Infra Merah (LUSI DRONE) diambil dari Kawah Lusi tahun 2015. Ditampilkan variasi suhu sepanjang lintasan (70-25oC)

Foto Mosaik Drone Kawah Lusi 2015Baseline Citra Satelit Google Earth 23 Agustus 2017, Disandingkan dengan Ditra Drone Januari 2018 (dengan trend yang masih sama), 15 Juni 2018 pada Hari Lebaran dan Pasca Gempa Madura, terakhir Juli 2018 mengalami Reorganissi Postur Geyser Sulung dan Bungsu.

ALBUM EVOLUSI POSTUR LUSI JANUARI – JULI 2018:

 

video terkait:

LUPSI: LUMPUR PANAS SIDOARJO, LAHIRNYA BPLS (1): 16 JUNI 2013

https://youtu.be/Y8Yd6E4-IRY

GEYSER LUSI LIBRARY AND VIRTUAL MUSEUM 2018

https://youtu.be/viKo-_Gabu0

Dinamika Mengasuh LUSI 10 Tahun: Unik, Kontroversi, Menarik Perhatian Dunia

https://youtu.be/7lnqz2bJ3KM

HARI BUMI 23 APRIL 2016, SISTEM LUSI MUD VOLCANO, MESIN BUMI YANG LUAR BIASA: SUSAN NORRIE

https://youtu.be/7EoSa1xmvQM

Dinamika Mengasuh LUSI 10 Tahun: Unik, Kontroversi, Menarik Perhatian Dunia: 27 FEB 2018

https://youtu.be/7lnqz2bJ3KM

HSF/BPLS International Scientific Symposium on Indonesia’s Mud Volcano 26 Mei 201

https://youtu.be/H8FuTtuOvcE

BERKUNJUNG PADA HUT LUSI 12 TAHUN: 1 JUNI 2018

https://youtu.be/5nY7M_OImp8

Simulasi Dinamika Lusi 2006-2017 dari Citra Indraja: 23 Mei 2018

https://youtu.be/lr-EdXTfuC0

Dinamika Mengasuh LUSI 10 Tahun: Unik, Kontroversi, Menarik Perhatian Dunia: 27 Februari 2018

https://youtu.be/7lnqz2bJ3KM

DINAMIKA LUSI DARI WAKTU KE WAKTU (2004-2009)

https://youtu.be/ur1pfDRNdJQ

PERINGATAN 1 TAHUN KUNJUNGAN PRESIDEN RI JOKO WIDODO KE LUSI

https://youtu.be/uki_kkCQlOQ

10 TAHUN MENGASUH LUSI

https://youtu.be/p8xSqpIa9Mw

SEBELUM MENGASUH LUSI, TELAH MENEMUKAN MUD DIAPIR DAN MUD VOLCANO

https://youtu.be/sCbaPhYCfcA

GEYSER LUSI LIBRARY 2018: BIKE TO WORK LUSI 23 APRIL 2011

https://youtu.be/K1LhHXtzh7g

6 Tahun Peringatan Simposium Internasional Ilmiah Lusi 25-26 Mei 2011

https://youtu.be/yClSNweRjPQ

3 TAHUN SEMBURAN LUMPUR PANAS DI SIDOARJO LUPSI: Harmonisasi Fenomena alam/Geologi dan Upaya Manusia

https://youtu.be/7t5hQBIiIRw

3 TAHUN SEMBURAN LUMPUR PANAS DI SIDOARJO LUPSI: Harmonisasi Fenomena alam/Geologi dan Upaya Manusia

https://youtu.be/7t5hQBIiIRw

INTEGRASI CITRA PENGINDERAN JAUH DAN SEISMIK REFLEKSI 2D DAN 3D PADA PENANGGULANGAN LUSI 2017

https://youtu.be/ZCvZ5KPpErY

KEUNIKAN BENCANA LUSI 2008

https://youtu.be/e-zFKHD80QI

KONTRIBUSI KOMUNITAS “BANGGA BERKEBAYA” UNTUK PENANGGULANGAN BENCANA LUSI

https://youtu.be/Yo8gKFbs3W0

BIKE TO WORK LUSI 23 APRIL 2011

https://youtu.be/YeOKqZhGxGM

Dinamika Mengasuh LUSI 10 Tahun: Unik, Kontroversi, Menarik Perhatian Dunia

https://youtu.be/7lnqz2bJ3KM

Dead River, south of Lusi mud volcano, May 2011, Hardi

https://youtu.be/4PJSUVzPf6o

Geyser Lusi mud volcano 2014: B2WL

https://youtu.be/M4HpKOCWDdk

lusi 9 Tahun, Postur Barat Lusi mud volcano, Citra Google Earth Oktober 2014

https://youtu.be/28f9nO_pf0E

3 AGUSTUS 2012, PULSA ALIRAN LUMPUR BARU POLA BANJIR BANDANG DI KALI SELATAN LUSI

https://youtu.be/Se8SWVsEE18

9 OKTOBER 2012, PEMANTAPAN PINTU MASUK JALAN MOBIL KE NIRWANA, UTARA LUSI

https://youtu.be/lX1A5aj3Nrs

Keajaiban/Misteri Alam antara Lusi, gunung lumpur dan Penanggungan gunung volkanik: 7 AGUSTUS 2012

https://youtu.be/9TO_l2eZWiw

PULAU LUMPUR, PROGRADASI DELTA PORONG: 10 JULI 2013

https://youtu.be/ESeGpOm51fE

ANDIANI BADAN GEOLOGI KESDM ‘SRIKANDI LUSI” MENJELAJAH GUNUNG LUSI: 18 JANUARI 2013

https://youtu.be/nydlSpZ8OOw

29 JUNI 2013, BIKE WORK TO LUSI (BWT-LUSI), KAWAH BUNGSU DAN MUARA KALI SELATAN LUSI MUD VOLCANO: 29 JANUARI 2013

https://youtu.be/Yf_OY3qRbC0

31 JULI EKSPEDISI MENJELAJAH KALI P68S DARI HULU KE HILIR DI POND RENO: 31 JULI 2013

https://youtu.be/ddBuB7HJ0QY

14 SEPTEMBER 2013 SEMBURAN GANDA LUSI MUD VOLCANO, DILIHAT DARI NIRWANA, UTARA

https://youtu.be/x2xBaEx8ilU

21 JUNI 2014, HUMAN INTEREST, SENJA WISATAWAN DI UTARA LUSI

https://youtu.be/_H7XikvMq34

LUSI 8 TAHUN, KILAS BALIK MUNTAHAN LUMPUR PEKAT DI DOME

https://youtu.be/F5v591YX6wc

EXPEDITION TO NORTH LUSI VOLCANO (1): 26 MEI 2012

https://youtu.be/k8sKGgFwC1k

A new deformation in the NE Lusi Mud Volcano: 2 April 2012

https://youtu.be/d1LEn0IKp8w

30 OKTOBER 2013, STRUKTUR BUNGA LUMPUR, TIMUR KAWAH LUSI MUD VOLCANO

https://youtu.be/cx5oaGEnRNY

30 Agustus 2013, SEMBURAN GANDA LUSI, INDIKASI MUD VOLCANO MASIF DINAMIS

https://youtu.be/AnA0dTcDR8g

11 DES 13, POSTUR KALI SIRING DARI HILIR KE HULU, MANDI LUMPUR

https://youtu.be/4n94AHvulkQ

LUSI 8 TAHUN: PERULANGAN DEFORMASI RAYAPAN PUNGGUNGAN: 22 APRIL 2014

Dinamika Lusi mud volcano, limpasan di lereng selatan Lusi mud volcano

EKSPEDISI KE UTARA LUSI P68, ANTISIPASI PENCEMARAN DAN BANJIR DI KALI KETAPANG: 24 JAN 2013

Semburan Lusi di Dome yang masih bersemangat: 7 JULI 2012

New Strike-slip fault, NE Lusi mud volcano, 29/03/2012

MEMAKNAI PERPRES 40/2009: DINAMIKA PARADIGMA KEBIJAKAN PENANGGULANGAN LUSI

Juli 13, 2018

COVER STORY:

Slide20

Judul Ceramah di Pasca Program Sarjana UPN/UGM Mei 2010 “4 Tahun Lumpur Panas Sidoarjo (LUPSI): Paradigma Baru dari Bencana ke Manfaat”, pasca diberlakukannya Perpres 40/2009 tentang perubahan Kedua Perpres 14/2007 tentang BPLS.

LUSI LIBRARY FILE:

lulib

Pemaknaan Gambar (Cover story):

Pada Ceramah Umum di Kampus UPN dihadiri Staf Pengajar dan khususnya mahasiswa Pasca Sarjana dari Universitas Pembangunan Veteran Yogyakarta dan Universitas Gajah Mada (UGM) terutama pada disiplin Ilmu Kebumian, akan disampaikan suatu Paradigma Baru dari Penanggulangan Bencana Lumpur Panas Sidoarjo (LUPSI) Menuju Pemanfaatan dalam arti yang luas.

Mengingat bahwa Bencana Lupsi dikendalikan oleh semburan mud volcano yang terunik, terbesar dan paling kontroversi terkait penyebab dan pemicunya. Disamping itu, hasil kajian Ilmu Kebumian sampai saat itu telah semakin mengkerujut bahwa fenomena Lupsi akan berlangsung lama, dan sudah tidak akan/dimatikan dengan teknologi yang ada.

Sehingga pada bagian awal akan dibahas secara komprehensif, integral dan holistik dari “DINAMIKA TUMBUH DAN BERKEMBANGNYA SISTEM MUD VOLCANO LUPSI DARI WAKTU KE WAKTU TERMASUK ISU AKTUAL DAN KRITIS MENGIRINGINYA”.

Sesuai kata kunci dari Judul Ceramah, akan disampaikan merupakan suatu Pandangan Baru dan pandangan ke depan (forward looking) bagaimana mewujudkan sutu transformasi Dari Bencana ke Manfaat, dengan suatu pilar “HIDUP HARMONI DENGAN BENCANA. Pada Outlook mencakup:

  • Lusi sebagai wahana LABORATORIUM ALAM MENJADI PUSAT UNGGULAN STUDI MUD VOLCANO HIBRIDA DI DUNIA;
  • Lusi telah diposisikan sebagai salah satu dari 10 Warisan Bumi (Geoheritage) di Pulau Jawa akan diarahkan menjadi suatu Taman Bumi (Geopark) dengan mengedepankan Geowisata (Wisata berbasis Alam);
  • Lumpur Lusi yang berasal proses daur ulang sedimen di bawah permukaan dan dipengaruhi oleh kondisi hidrotermal karena dekat dengan gunung api, berpotensi baik dari material yang dibawahya, maupun pemanfaatan dampak suhu tinggi antara lain untuk rekreasi dan pengobatan air panas serta pembangkit panas bumi berskala kecil (small scale hydrothermal system).

Secara umum cover story menyampaikan pesan-pesan “Pemberdayaan Wacana Publik Paradigma Baru LUSI mud volcano” mencakup:

Pengendali mekanisme Bencana Lupsi:

  • Semburan bersiklus Geyser dua kawah berasal dari bawah permukaan mencapai >4400m, terbesar didunia relatif tanpa henti dengan intensitas semburan pernah mencapai 180.000m3/h (2006) rata-rata 100.000m3/h (2007-2009) menurun menjadi `35.000M3/h, akan berlangsung lama, dan sudah sulit/tidak dapat/tidak perlu dimatikan.
  • Luapan lumpur panas dikeluarkan dari pusat semburan, sejak 2010 menjadi dua titik, ditampung di kawah, secara alami dialirkan melalui sungai-suangi kearah daerah depresi (cekungan).

Pada mitigasi bencana telah dibangun Tanggul-tanggul penahan luapan lumpur pada kondisi darurat (emergency) dari bahan pasir dan batu (sirtu), membentuk kolam-kolam penampung Lupsi dan air sementara.

Selanjutnya dialirkan menggunakan mekanisasi kapal keruk dan pompa booster dengan outlet di Kali Porong. Tahap akhir secara alami dengan menggunakan kekuatan energi bebas (free energy) yang dimilikinya lumpur di outlet akan diangkut menuju pembuangan akhir di palung dalam dari Selat Madura.

Bahaya geologi (Geohazard) sebagai dampak berganda sistem mud volcano yaitu deformasi amblesan, retak, patahan, dan bualan (bubble) dengan paparan gas metan yang mudah terbakar.

  1. Dampak yang ditimbulkan:
    • Merupakan yang pertama pada zaman kehidupan manusia modern, Bencana Lupsi justru terjadi pada area permukiman padat dan pada kawasan pertumbuhan ekonomi baik lokal dan regional. Umumnya semburan mud volcano lainnya yang berjumlah ribuan di dunia terjadi pada daerah terpencil (remote area) yang jauh dari kawasan Permukiman. Disamping itu semburan merusak umumnya terjadi sesaat, selanjutnya memasuki tahap dormant (istirahat), seperti halnya kejadian erupsi gunungapi.
    • Bencana LUPSI secara umum telah menimbulkan memporakporandakan sendi-sendi kehidupan masyarakat, 14 korban manusia meninggal, pengungsian lingkungan berjumlah puluhan ribu berlangsung lama, infrastruktur umum dan energi lumpuh dan rusak, dampak lingkungan fisik dan hayati.
    • Dua pusat penampungan atau pengungsian sementara dalam jumlah yang besar dan berlangsung lama adalah di Pasar Baru Porong terkait dengan Peta Area Terdampak 4 Desember 2006 dan 22 Maret 2007 (Perpres 14/2007), dan disepanjang Jalan Tol Lama di desa Besuki Barat ditangani dengan Perpes 48/2008 mencakup 3 Desa di luar PAT, pertama kalinya Pemerintah/BPLS menangani masalah sosial kemasyarakatan dengan pola “bedol desa” dilakukan pembelian tanah dan bangunan wara dengan skema bertahap diawali dengan Bantuan Sosial.

Outcome Pemulihan dan Pembangunan Kembali Sendi-sendi kehidupan warga dan wilayah secara holistik:

  • Penanganan masalah sosial kemasayarakatan dan “Total Bedol Desa” menuju permukiman kembali
  • Pada hakekatnya warga terdampak dijauhkan dari wilayah Bencana Lupsi yang masih terus berlangsung, baik yang terkena dampak langsung dimana aset tanah dan bangunannya telah ditenggelamkan atau wilayahnya tidak layak huni.
  • Pola pemukiman kembali adalah dengan pola “Total Bedol Desa” dimana warga terdampak setelah hidup di pengungsian akan menempuh kehidupan baru di wilayah baru secara kolektif atau memilih sesuai dengan pilihannya. Hal mungkin yang pertama kalinya dari berbagai Penanggulangan Bencana Alam di Indonesia, seperti letusan gunungapi, banjir atau gempabumi dimana aset tanah umumnya masih dapat dimanfaatkan sedangkan rumah dapat diperbiki atau dibangun kembali.

Pada foto ditampilkan salah satu permukiman kembali warga desa Renokenongo, yang sebelumnya menempati Pengungsian di Pasar Baru Porong, selanjutnya secara kolektif telah “Total Bedol Desa” dengan skema Jual Beli tanah dan bangunan secara bertahap (20 dan 80%) diawali dengan Bantuan Sosial (Bansos), akhirnya telah menempuh Hidup Baru di permukiman “Reno Joyo”.

Relokasi Infrastruktur secara terintegrasi dan tandem

  • Secara umum juga yang pertama kalinya pada Penanggulangan Bencana di Indonesia, dimana infrastruktur umum dan energi yang telah lumpuh total dan mengalami kerusakan, selanjutnya dilakukan relokasi pada suatu TRASE RELOKASI YANG TERINTEGRASI. Dalam arti grand design trasi relokasi yang sekaligus akan menampung pembangunan baru Jalan Tol, Jalan Arteri, Kereta Api, Pila PDAM, Jaringan gas alam, Jaringan Listrik PLN.
  • Pada foto ditampilkan salah satu rancangan dari Relokasi Jalan Tol Ruas Porong Gempol yang diapit oleh Jalan Arteri.

 

PARADIGMA KEBIJAKAN

Slide18

Hubungan Pengendali Mekanisme Bencana Lusi (Semburan, Luapan, Geohazard dan Lingkungan) dengan Paradigma Kebijakan Penanggulangan Lusi (Perpres terkait), yang merayap secara perlahan, beralih dari dikendalikan Seburan-Luapan menjadi didominasi oleh GeoHazard/Deformasi dan Lingkungan hidup.               Pada Awal Kebencanaan Kebumian Lusi telah ditentukan  (Peta Bencana) sebagai Peta Area Terdampak (PAT) yaity 4 Desember 2006 (PAT-1) berlanjut pada 22 Maret 2007 (PAT-2) dimana mengikuti tahapan: Respon Darurat – Pemulihan  (Pengungsian 1, Gejolak Sosmas) – Awal Pembangunan Kembali (skema penanganan sosmas, Trase Relokasi Infrastruktur)-Mitigasi upaya penanggulangan semburan (upaya mematikan dan mengurangi debit luapan lumpur), pengaliran lumpur ke laut, penanganan geohazard. Manajemen Bencana dipayungi oleh Keppres (TIMNAS 2006) dan Perpres (BPLS 2007, 2008, 2009, lanjut);                                                          Perluasan PAT selanjutnya (PAT-3) ke dua mencakup wilayah 3 Desa di luar PAT, terutama pengendali bencana adalah luapan lumpur pasca Tanggul di selatan PAT Jebol,  menimbulkan “Siklus Bencana Baru” ditanganan dengan tahapan bencana Respon Darurat, Pemulihan (Pengungsian di Besuki Barat – Gejolak sosmas)-Pembangunan kembali dengan skema jual beli bertahap seperti di PAT di payungi dengan Perpres 49/2008;                                                                                                              Pada  perluasan PAT  berikutnya (PAT-4) mencakup wilayah 9 RT di luar PAT, lebih dikendalikan oleh mekanisme Geohazard, Lingkungan, Gejolak Sosial Kemasyarakatan wilayah dinyatakan menjadi Tidak Layak Huni, tahap pemulihan tidak terjadi pengungsian baru, wilayah dikosongkan paling lama 2 tahun, menuju tahap rehabilitasi dan pembangunan kembali melalui skema sebagaimana dipayungi oleh Perpes 40/2009 dan 68/2011.                                                                             Perluasan PAT terakhit (PAT-5/6)   mencakup wilayan 55 dan 56 di Luar PAT, dimana pengendali mekanisme bencana utamanya Geohazard, disamping Lingkungan dan Gejolak Sosial Kemasyarakatan selanjutnya  wilayah dimaknai sebagai Wilayah Tidak Aman, dipayungi dengan Perpres 37/2012 dan Perpres 33/2013.                              Dari gambaran di atas menunjukkan bahwa Penanggulangan Bencana Kebumian Lusi lebih unik dan komplek dari kaidah Penanggulangan Bencana yang umum dengan tahapan: KESIAPAN, TANGGAP DARURAT, PASCA DARURAT, PENCEGAHAN DAN MITIGASI. Disamping itu karena Pengendali mekanisme utama Bencana Lusi yaitu semburan Geyser Lusi-Luapan Lumpur-GeoHazard masih dan akan berlangsung lama di dalam PAT sehingga Tahapan PENCEGAHAN DAN MITIGASI DIIKUTI PERSIAPAN MASIH TERUS BERLANGSUNG.

PENANGGULANGAN BENCANA KEBUMIAN LUSI 2006-2015

Slide08

Pola Pikir Penanggulangan Lumpur Sidoarjo dengan pendekatan Komprehensif, Integral dan holistik: Potret, Isu Aktual, Paradigma Kebijakan, Kondisi yang diharapkan, Perubahan Lingkungan Strategi, Output dan Outcome.

DIKONTRIBUSIKAN OLEH: PROF. DR. HARDI PRASETYO

Wakil Kepala BPLS

slide14

Pemaknaan Perpres 14/2007 tentang BPLS dengan dimensi Kewilayahan PAT 22 Maret 2007, dan Perpres 48/2008 tentang Perubahan Pertama mencakup penanganan masalah sosial kemasyarakatan di wilayah 3 Desa di Luar PAT dengan rasionalisasi untuk meningkatkan Efisiensi Pengaliran Lusi ke Kali Porong.

Memahami lebih lanjut perpres 40/2009

Tentang perubahan kedua atas peraturan presiden nomor 14 tahun 2007 tentang Badan Penanggulangan Lumpur sidoarjo

Suatu Evaluasi dan Analisis terhadap Perubahan Mendasar: 

Implikasinya pada Misi Nasional BPLS ke depan

Dikontribusikan Oleh: Dr. Ir. Hardi Prasetyo, September  2009

slide7

Kumulatif dari Evolusi Paradigma Kebijakan terkait Status Wilayah Penanggulangan Bencana Lusi dari 2007-2012. Perpres 40/2009 mencakup wilayah 9 RT di luar PAT, terutama di sisi barat PAT 22 Maret 2007.

PROLOG

Peraturan Presiden No. 40 Tahun 2009 ditetapkan oleh Presiden RI pada tanggal 23 September 2009, sebagai antisipasi terjadinya perubahan mendasar.

Baik pada kondisi aktual di lapangan, maupun pada Lingkungan strategis Global, Nasional dan Lokal.

Perubahan tersebut selanjutnya telah memberikan implikasi yang luas terhadap implementasi Bapel BP pada misi nasional penanggulangan lumpur di Sidoarjo.

Substansi Perpres 40/2009 merupakan perubahan ke dua dari Perpres 14/2007 tentang BPLS,  sebagaimana telah dirubah menjadi Perpres 48/2008 dimana sebagian merupakan masukan dari Bapel BPLS,.

Sebagai solusi terhadap isu kritis dan aktual yang berkembang dilapangan, serta suatu realita terbatasnya landasan hukum hukum yang memadai.

EPILOG

Dengan ditetapkannya Perpres 40/2009, diharapkan upaya penanggulangan semburan lumpur dan penanganan luapan lumpur serta penanganan masalah sosial kemasyarakatan baik di dalam maupun di luar PAT 22 Maret 2017, dapat dilaksanakan oleh Bapel BPLS dan seluruh stakeholders secara lebih efektif.

Sehingga dampak langsung atau tidak kepada masyarakat dan infrastruktur dapat lebih tertangani secara integral dan holistik.

 Yang pada akhirnya sendi-sendi kehidupan masyarakat terhadap dampak semburan lumpur panas di Sidoarjo dapat dipulihkan.

Memahami lebih lanjut perpres No. 40/2009

Tentang perubahan kedua atas peraturan presiden nomor 14 tahun 2007 tentang Badan Penanggulangan Lumpur Sidoarjo (BPLS)

Suatu Evaluasi dan Analisis terhadap Perubahan Mendasar:

Implikasinya pada Misi Nasional BPLS ke depan

ESENSI DAN POKOK-POKOK PERPRES 40/2009

Perpres 40 tahun 2009 tentang Perubahan Kedua Atas Peraturan Presiden Nomor 14/2007 tentang BPLS, ditetapkan dengan perubahan pada bagian-bagian, yaitu:

  1. Hal yang menjadi pertimbangan;
  2. Peraturan perundang-undangan yang digunakan sebagai acuan;  dan
  3. Pada substansi utama dilakukan perubahan pada Pasal 9 (tugas pokok Deputi Bidang Operasi, Bapel BPLS) dan Pasal 15 (pembagian tanggung jawab finansial dan operasional antara Pemerintah dan Lapindo).

Pasal 15 pada intinya merupakan peralihan tanggung jawab finansial dan operasional dari upaya penanggulangan semburan dan penanganan luapan lumpur oleh Bapel BPLS,

Dimana sebelumnya dilaksanakan oleh Lapindo  sesuai dengan ayat 5, Pasal 15, Perpres 14/2007. Selanjutnya ditambah dengan misi mitigasi yang sebelumnya telah dilaksanakan oleh BPLS sejak Oktober 2008.

Sistematikan Perpres 40/2009 diawali dengan Hal yang menjadi Pertimbangan, Landasan Hukum yang menjadi acuan, Pasal-Pasal yang mengalami perubahan

Gambar 1: Sistematika Peraturan Presiden No. 40/2009

 

Sedangkan Pasal 15 B, menentukan wilayah penanganan luapan lumpur di luar Peta Area Terdampak tanggal 22 Maret 2007 mencakup aspek-aspek:

  1. Tiga Desa di selatan PAT (Perpres 48/2008);
  2. Termasuk wilayah 9 RT dari 3 Desa yang terkena dampak semburan lumpur sehingga menjadi tidak layak huni;
  3. Pembayaran penanganan masalah sosial di tiga desa di luar PAT dengan skema 20%, 30% (tahun Anggaran 2009),  dan sisanya disesuaikan dengan tahapan pelunasan oleh PT Lapindo Brantas; dan

Diagram pokok-pokok perubahan Perpres 40/2009

Gambar 3. Diagram perubahan Perpres 14/2007, Perpres 44/2008 menjadi bagian dari Perpres 40/2009, pada Pasal-pasal 15-5, 15 B (1a), 15 B (8) dan 15 B (9)

 

Anatomi Perpres 40 tahun 2009 tentang Perubahan Kedua Atas Peraturan Presiden Nomor 14/2007 terdiri atas:

  • Hal yang menjadi pertimbangan;
  • 5 (lima) Hal yang menjadi acuan (diingat);
  • Pasal 1, merupakan protokol terhadap perubahan Perpres 14/2007 sebagaimana telah diubah dengan Perpres 48/2008;
  • Perubahan Pasal 9 huruf c dan d;
  • Ketentuan Pasal 15 dimana ayat (5) dihapus, ayat (6) diubah; Penambahan 1 (ayat) yaitu ayat (7);
  • Ketentuan Pasal 15 B ayat (5) diubah, penyisipan antara ayat (1) dan ayat (2) yaitu ayat (1a), dan penambahan 2 (dua) ayat, yaitu ayat (8) dan ayat (9).

POKOK-POKOK PERUBAHAN

HAL YANG MENJADI PERTIMBANGAN

Dalam rangka mengefektifkan upaya penanggulangan semburan lumpur dan penanganan luapan lumpur serta penanganan masalah sosial kemasyarakatan.

Sehingga diperlukan untuk menetapkan Perpres 40 tahun 2009 tentang Perubahan Kedua atas Perpres 14/2007 tentang Badan Penanggulangan Lumpur Sidoarjo.

HAL YANG MENJADI ACUAN (DIINGAT)

  • Pasal 4 ayat (1) UUD 1945;
  • UU No. 24 tahun 2007 tentang Penanggulangan Bencana;
  • UU No. 26 Tahun 2007 tentang Penataan Ruang;
  • UU No. 41 tahun 2008 tentang APBN tahun 2009;
  • Perpres No. 14 tahun 2007 tentang BPLS sebagaimana telah diubah dengan Perpres 48 Tahun 2008. 

PERUBAHAN PASAL 9

Pada intinya mengatur tupoksi Deputi Bidang Operasi yaitu ‘OPERASI terhadap upaya penanggulangan semburan lumpur dan penanganan luapan lumpur’.

Sebagai konsekuensi terjadinya pengalihan tugas dan tanggung jawab penanggulangan semburan dan luapan lumpur yang sebelumnya oleh Lapindo menjadi ke BPLS’, yaitu mencakup dimensi:

  • Menyelenggarakan Koordinasi Operasi;
  • Menyusun Rumusan Strategi dan Rencana Operasi;
  • Melakukan Operasi;
  • Melakukan penanganan luapan lumpur ke Kali Porong;
  • Mengadakan evaluasi dan pelaporan.

ESENSI PASAL 15

  • Ayat (1), (2) dan (4) tetap;
  • Ayat (3) dan (5) dihapus;
  • Ayat 6 (baru);

 

  • Biaya upaya penanggulan semburan lumpur;
  • Biaya pengaliran lumpur ke Kali Porong;
  • Biaya penanganan infrastruktur, termasuk infrastruktur penanganan luapan lumpur di Sidoarjo;
  • Dibebankan pada APBN dan sumber dana lainnya yang syah.

 

  • Ayat 7 (baru):
  •  Biaya tindakan mitigasi;
  • Yang dilakukan oleh Badan Pelaksana BPLS (masa lalu, saat ini dan ke depan);
  • Untuk melindungai keselamatan masyarakat dan infrastruktur (mencegah meluasnya PAT 22 Maret 2007)
  • Dibebankan kepada APBN.

ESENSI PASAL 15

Hal yang menjadi Pertimbangan Perpres 40/2009

Gambar 4. Hal yang menjadi Pertimbangan Perpres 40/2009

  • Ayat (1): Wilayah penanganan luapan lumpur di luar PAT 22 Maret 2007 adalah di Desa Besuki, Desa Pejarakan, dan Desa Kedungcangkring, Kecamatan Jabon dengan batas-batasnya (Perpres 48/2008);
  • Ayat (1a): Penanganan luapan lumpur di luar PAT pada Ayat (1) termasuk yaitu 9 RT di tiga Desa yang terkena dampak semburan lumpur berupa amblesan maupun semburan gas berbahaya sehingga menjadi tidak layak huni;
  • Ayat (2): Peta Wilayah penanganan luapan lumpur di luar PAT 22 Maret sebagaimana tercantum pada ayat (1) sebagai lampiran;
  • Ayat (3): Tidak berubah dari Perpres 48/2008;
  • Ayat (4): Tidak berubah dari Perpres 48/2008;
  • Ayat (5): Pembayaran penanganan masalah sosial kemasyarakatan pada  wilayah di luar PAT pada ayat (1) dilakukan secara bertahap dengan skema:
  1. 20% pada TA 2008;
  2. 30% pada TA 2009; dan
  3. Sisanya disesuaikan dengan tahapan pelunasan yang dilakukan oleh PT Lapindo Brantas (Pasal 15 ayat 2);
  • Ayat (6): Tidak berubah dari Perpres 48/2008;
  • Ayat (7): Tidak berubah dari Perpres 48/2008;
  • Ayat (8): Dalam rangka penanganan masalah sosial kemasyarakatan di wilayah 9 RT dari 3 Desa di luar PAT  ayat (1 a), wilayah tersebut dikosongkan demi keselamatan masyarakat untuk paling lama 2 (dua) tahun; dan
  • Ayat (9): Bagi warga yang tinggal sebagaimana pada ayat (8) tersebut pada saat proses wilayah tersebut dikosongkan, diberikan bantuan sosial berupa: a) kontrak rumah selama 2 tahun, b) bantuan tunjangan hidup selama 6 bulan, dan c) biaya evakuasi.

Pasal II

  • Perpres 40/2009 mulai berlaku pada tanggal ditetapkan pada tanggal 23 September 2009.

LAMPIRAN GAMBAR-GAMBAR : Baseline Perpres 14/07 dan 48/08

Diagram Sistematikan Perpres 14/2007 tentang BPLS, merupakan Induk dari Perubahan Peraturan Presiden berikutnya, terutama pada Pasal 15, merupakan pembagian tanggung jawab operasi dan finansial antara Pemerintah dan Lapindo.

Gambar 5 a dan b. Diagram Sistematika dan Pokok-pokok Perpres 14/2007 pada pembagian tanggung jawab Pemerintah dan Lapindo

Diagram  Sistematika Perpres 48/2008

 

Acuan Peraturan Perundang-undangan pada Perpres 48/2008

Hal yang menjadi Pertimbangan Perpres 48/2008

Gambar 7 dan b. Hal menjadi Pertimbangan dan Acuan Perpres  48/2008

Rincian Sistematika menyeluruh dari Proses Masukan (Input), Proses Perubahan dan Keluaran, serta Siapa Melakukan Apa?

Gambar 8 a dan b: Diagram Alur Pikir dan Kelembagaan PP 48/2008

FROM USA WITH LUSI: LOYC Vanderkluysen 2014

Juli 1, 2018

Blog ini ditampilkan dalam rangka menyambut Tim Ahli Kebumian Amerika pada even “FROM USA WITH LUSI”, mengunjungi Lusi hari ini termasuk menerbangkan Drone dengan sensor infra merah.

loyc1

Prof. Dr. Loyc Vanderkluysen tadi pagi berada di Lusi siap menerbangkan Drone. Foto Chandra PPLS.

Lusi Library sebelumnya:

Vanderkluysen 2014 Komposisi dan pelepasan ledakan gas pada Lusi mud volcano

 LUSI LIBRARY FILE 2015
Tinjauan dalam bahasa Indonesia
Dikontribusikan oleh Dr. Hardi Prasetyo
http://00ahli-lusi-2015.blogspot.com/2015/02/vanderkluysen-2014-komposisi-dan_11.html

Composition and flux of explosive gas release at LUSI mud volcano (East Java, Indonesia)

Sumber: https://agupubs.onlinelibrary.wiley.com/doi/full/10.1002/2014GC005275

Loÿc Vanderkluysen

Corresponding Author

School of Earth and Space Exploration, Arizona State UniversityTempe, Arizona, USA

Now at Department of Biodiversity, Earth & Environmental Science, Drexel University, PhiladelphiaPennsylvania, USA

Correspondence to: L. Vanderkluysen, E-mail address:loyc@asu.edu

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Michael R. Burton

Istituto Nazionale di Geofisica e Vulcanologia—Sezione di PisaPisa, Italy

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Amanda B. Clarke

School of Earth and Space Exploration, Arizona State UniversityTempe, Arizona, USA

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Hilairy E. Hartnett

School of Earth and Space Exploration, Arizona State UniversityTempe, Arizona, USA

Department of Chemistry and Biochemistry, Arizona State UniversityTempe, Arizona, USA

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Jean‐François Smekens

School of Earth and Space Exploration, Arizona State UniversityTempe, Arizona, USA

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First published: 18 June 2014
Cited by: 17

Conclusion

LOYC2014-8

The activity at LUSI mud volcano observed in 2011 was dominated by the periodic bursting of bubbles approximately 3 m in diameter which trigger mud fountains ∼10 m in height, and have regular quiescent periods of 1–3 min long.

Infrared absorption spectrometry reveals that the gas released during explosions consists of 98 mol % water vapor, 1.5 mol % carbon dioxide, and 0.5 mol % methane, and that there is no detectable gas flux during quiescent intervals.

LUSI releases approximately 2300 t yr−1 of methane, 30,000 t yr−1 of CO2, and 800,000 t yr−1 of water vapor. The flow can be described as slug flow and our gas‐flux measurements place an upper‐bound on corresponding mud‐water flux at 105 m3 d−1.

Although carbon dioxide and methane bubbles nucleate deep in the system (hundreds to thousands of meters deep), the primary driving mechanism for the observed cyclic bubble‐bursting activity is decompressional boiling of the water in the system, which initiates tens of meters below the surface.

Given the regime map of the system presented here, changes in gas flux while still exhibiting slug flow can be used to constrain maximum liquid flux. Furthermore, a significant change in gas flux alone could disrupt the slug flow regime.

Abstract

The LUSI mud volcano has been erupting since May 2006 in the densely populated Sidoarjo regency (East Java, Indonesia), forcing the evacuation of 40,000 people and destroying industry, farmland, and over 10,000 homes.

Mud extrusion rates of 180,000 m3 d−1 were measured in the first few months of the eruption, decreasing to a loosely documented <20,000 m3 d−1 in 2012.  The last few years of activity have been characterized by periodic short‐lived eruptive bursts.

In May and October 2011, we documented this activity using high‐resolution time‐lapse photography, open‐path FTIR, and thermal infrared imagery.

Gases (98% water vapor, 1.5% carbon dioxide, 0.5% methane) were periodically released by the bursting of bubbles approximately 3 m in diameter which triggered mud fountains to ∼10 m and gas plumes to hundreds of meters above the vent.

During periods of quiescence (1–3 min), no appreciable gas seepage occurred. We estimate that LUSI releases approximately 2300 t yr−1 of methane, 30,000 t yr−1 of CO2, and 800,000 t yr−1 of water vapor.

Gas bubble nucleation depths are >4000 m for methane and approximately 600 m for carbon dioxide; however, the mass fractions of these gases are insufficient to explain the observed dynamics.

Rather, the primary driver of the cyclic bubble‐bursting activity is decompressional boiling of water, which initiates a few tens of meters below the surface, setting up slug flow in the upper conduit. Our measured gas flux and conceptual model lead to a corresponding upper‐bound estimate for the mud‐water mass flux of 105 m3 d−1.

1 Introduction

Mud volcanism is a worldwide phenomenon, typically occurring in association with hydrocarbon‐bearing basins in compressional tectonic settings. Mud volcanoes are classically understood as the surface expression of piercement structures rooted in deep‐seated overpressured sediments [e.g., Bishop, 1978; Brown, 1990; Kopf, 2002]. On a global scale, the range in chemical and isotopic compositions measured in fluids released at mud volcanoes reflects the complex variety of their fluid sources. These fluid sources often involve a combination of surface waters and seawater, sediment pore fluids, thermogenic and biogenic gases, hydrothermal and volcanic inputs, and deep‐seated mantle or crustal volatiles [e.g., Dimitrov, 2002; Kopf and Deyhle, 2002; Kopf et al., 2003; You et al., 2004; Mazzini et al., 2007, 2012; Lichtschlag et al., 2010]. In a broad context, the release of fluids from mud volcanism is estimated to be a significant contributor both to fluid flux from the lithosphere to the hydrosphere, and to the atmospheric budget of some greenhouse gases, particularly methane [e.g., Henry et al., 1996; Kopf and Behrmann, 2000; Mörner and Etiope, 2002; Etiope et al., 2002; Kopf, 2003; Etiope, 2005].

The release of fluids at mud volcanoes during repeated explosive episodes has been documented at numerous sites [e.g., Higgins and Saunders, 1974; Guliev, 1992; Chigira and Tanaka, 1997; Hovland et al., 1997; Mellors et al., 2007; Deville and Guerlais, 2009; Manga et al., 2009; Mazzini et al., 2009; Deville et al., 2010], though the origin of the explosive cyclicity is a matter of ongoing study [e.g., Murton and Biggs, 2003; Zoporowski and Miller, 2009]. Typically, mud volcano eruptions last several days before returning to a phase of dormancy [e.g., Shnyukov et al., 1986; Aliyev et al., 2002; Deville and Guerlais, 2009].

1.1 The LUSI Mud Volcano

The name of the LUSI mud volcano is derived from the contraction of the Indonesian terms lumpur Sidoarjo, meaning “mud of Sidoarjo,” i.e., the name of the regency where the mud volcano is located (Figure 1). LUSI is part of a cluster of active and ancient mud volcanoes scattered over eastern Java as well as on the island of Madura (Figure 1). Mud effusion started at LUSI on the morning of 29 May 2006, in a location where no historical mud volcanism has been documented, although historical mud volcanoes have been documented nearby, and mud eruptions are currently ongoing within 25 km of LUSI. LUSI is unique in multiple aspects: peak flow rates of 180,000 m3 d−1, measured in September 2006, are the highest ever recorded at a mud volcano [e.g., Mazzini et al., 2007; Davies et al., 2007, 2011]; as of 2011, an estimated 40,000 people have been relocated as a result of mud flows advancing into inhabited areas, and approximately $300 million USD (2.7 trillion Indonesian rupiah) has been paid in compensation for the loss of land, buildings, and infrastructure [Richards, 2011]; and the area affected by the mud flows, largely bound by an artificial levee system reaching 12 m high on its western side, is ∼6.2 km2 (as of February 2012; Figure 2), making LUSI one of the largest known mud volcanoes on Earth. Mazzini et al. [2012] postulated that these unique features result from the fact that LUSI is not a mud volcano sensu stricto, and they argue that LUSI instead represents a sediment‐hosted hydrothermal system.

 

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Map of East Java placing LUSI in the context of local volcanism (red triangles) and mud volcanism (yellow triangles). Insert: Location of Java in Southeast Asia.

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2011 Geoeye‐1 true color image of LUSI, showing the locations of the FTIR spectrometer (red square) and IR source (orange circle) during active‐source measurement sessions. Geoeye‐1 Satellite Image © Centre for Remote Imaging, Sensing and Processing, National University of Singapore (2011).

Mazzini et al. [2007] indicated that mass fluxes were relatively low (<40,000 m3 d−1) early in the eruption, from 29 May to 1 August 2006, followed by strong “geyser‐like” behavior in the second half of 2006 and peak flow rates of 1.2–1.8 × 105 m3 d−1. These authors also reported pulsatory behavior in August and September 2006, with a period of ∼30 min, and again in February 2007, with a period of 1.5 h, which they interpreted as “a quasi‐hydrothermal behavior of the eruptive system.” In June 2007, volume flow rates were still approximately 110,000 m3 d−1 and have, in a general sense, been decreasing to <20,000 m3 d−1 as of October 2011 [Mazzini et al., 2007, 2012; this study].

Direct sampling of gases emitted at LUSI by Mazzini et al. [2007, 2012] reveals that the composition of volatiles released from the main vent may have changed slightly since its inception. Early in the eruption, very high concentrations of hydrogen sulfide (H2S) were measured: up to 500 ppm the day before the eruption at a nearby drill rig (which forced its temporary evacuation), and 35 ppm on the day of eruption initiation [Mazzini et al., 2007; Sawolo et al., 2009]. By 2007, H2S concentrations had fallen below detection levels (0.5 ppm). Carbon dioxide, CO2, is the dominant volatile carbon species along with smaller amounts of methane, CH4, and higher hydrocarbons. The CO2/CH4 volume ratios reported for 2006 and 2007 were 2–4 and the ratio increased to 7–11 in 2008 and 2010 [Mazzini et al., 2007, 2012]. By contrast, these same publications report that, from 2006 to 2011, gas seeps from LUSI’s satellite vents were methane‐dominated [Mazzini et al., 2007, 2012]. Thus, the balance of previous work [Mazzini et al., 2007, 2012] suggests the main vent has generally been carbon dioxide‐dominated, whereas satellite vents have been methane‐dominated. Gas mass or volume fluxes cannot be derived from these point‐sample analyses, and water vapor concentrations in LUSI’s eruptive gases have not been measured prior to this study.

The objectives of the present study were twofold: (1) determine, at high temporal resolution, the composition and daily flux of gases emitted by the LUSI mud volcano (East Java, Indonesia; Figure 1) both during and between periodic eruptive bursts; and (2) use these measurements of gas release at the surface to derive a conceptual model of the eruption mechanisms controlling periodic bursts, based on the thermodynamic properties of the measured fluid species and known behavior of multiphase systems of this type. For these purposes, from 15 to 18 October 2011, we deployed a Fourier transform infrared spectrometer (FTIR) at LUSI, in open‐path mode using a portable infrared source. Although the concentration of gas species can often be determined with more accuracy by direct sampling, open‐path FTIR has three principal advantages over other methods: (1) with a measurement every few seconds, it has a very high temporal resolution; (2) thanks to path lengths of tens of meters, it can measure a transect through the plume, providing more representative measurements than individual point‐samples taken from a potentially heterogeneous medium; and (3) measurements are done remotely, providing increased safety while monitoring an active natural hazard. The high temporal resolution is essential to capturing the details of the cyclic activity, given characteristic time scales on the order of minutes and rapid variations within individual explosive events, and therefore is critical to linking surface measurements to subsurface dynamics.

2 Gas Measurement Methodology and Data Collection

Measurements were conducted using a Midac (www.midac.com) open‐path Fourier transform infrared spectrometer (OP‐FTIR), model M4401‐S, with a liquid nitrogen‐cooled mercury cadmium telluride photoconductive detector. The chassis was made of sheet metal, reducing weight, and contained an integrated 3 in. diameter telescope, which narrowed the field of view of the spectrometer from 20 to 10 mrad. In contrast to the usual configuration for such spectrometers, this chassis included an aperture stop at the focal point of the integrated telescope, reducing incoming off‐axis light rays. The spectrometer was controlled via a PCMCIA interface connected to a laptop computer running the Essential FTIR software package (www.essential.com).

The OP‐FTIR campaign was conducted at LUSI from 15 to 18 October 2011. Since this OP‐FTIR campaign represented the first of its kind at a large‐scale mud volcano or hydrothermal system, we needed to develop an original methodology for measuring the gases released during the mild explosions at the mud volcano. There are four main methods that can be used to measure gases with OP‐FTIR, each with a different source of infrared (IR) radiation: passive mode, emission mode, active mode, and by solar occultation [Oppenheimer et al., 1998]. In the passive mode, naturally occurring hot rock or gases can be used as a source of radiation, producing an absorption spectrum [Allard et al., 2005]. In emission mode, the radiation emitted from the target gases themselves is used to produce emission spectra [Love et al., 1998]. In active mode, a portable infrared lamp is set up such that target gases are between the lamp and the spectrometer [Burton et al., 2000]. The lamp and the spectrometer are then carefully aligned and absorption spectra collected. And finally, in solar occultation mode, the sun is used as the radiation source [Francis et al., 1998; Duffell et al., 2001]. All these methods were considered before measurements began.

On 15 October, we attempted to obtain spectra in passive mode, targeting the region immediately above the main vent, using the mud itself as the radiation source. The spectrometer was carried to the closest accessible point, which was ∼400 m from the main gas and explosion source (closer approach was impossible because instruments and workers would sink into the mud); unfortunately, the intensity of radiation measured between and during explosions was too weak to allow absorption spectra to be recorded. We considered performing emission measurements, but our equipment did not include calibrated sources to allow radiometric calibration of the instrument, and so this approach was excluded. The advantage of this measurement mode would have been acquisition of gas measurements very near the source, reducing possible effects of air entrainment and reactions between gas phases. However, as the reader will see after the presentation of results below, the main measured gases are generally nonreactive, dilution by atmospheric gases can be accounted for, given our approach, and water vapor condensation should have a minor effect on gas fluxes other than H2O vapor.

During the visit on 15 October, we could smell gases produced from the mud volcano on the artificial levee, 800 m downwind (westward) of the main vent (Figure 2). We therefore decided to attempt active source IR measurements in that location. On 16 October, we set up the infrared lamp and spectrometer such that the gas plume from the mud volcano would pass between the active IR source and the spectrometer. There were three challenges in performing such measurements. First, while the artificial levee was 4–5 m above the surface of the mud at the foot of the levee, the accretion of erupted mud had created a mound at the mud volcano source, such that the emission point was topographically higher than the measurement point. This meant a strong, stable, and well‐directed wind was needed to keep a significant proportion of the plume close enough to the ground and between the source and spectrometer to allow us to make measurements. We correctly located the spectrometer and IR source (exact location relative to the vent, as well as the minimum distance between the two required to capture the plume in its entirety) using a series of tests in which we compared absorption at different distances and locations. When using short path lengths, small changes in wind direction were sufficient to move the plume in and out of the measurement path. As a result, to capture as much of the plume as possible, we typically used path lengths of 55–223 m. Measurements could be conducted downwind of the vent, thanks to the strong and stable winds that prevailed during the campaign. Second, there was a degree of uncertainty as to whether the gas emissions we measured were truly linked with the mud volcano or if another gas source could be interfering. This doubt was later resolved when a strong correlation was demonstrated between the timing of the explosive activity and peaks in gas concentrations (Figure 3b). Third, it was possible the gas compositions could change between the eruption point and the OP‐FTIR, but because the dominant eruptive gases (water, carbon dioxide, and methane) are largely unreactive over short time scales, we were confident that gas concentrations measured at the levee would be representative of gases emitted at the vent, in spite of the distance between the vent and measurement location. However, water vapor likely condensed in the plume over this distance, and our measurements thus represent a lower‐bound estimate of the water vapor emitted during eruptions.

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Figure 3

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(a) Picture of a bubble bursting at the LUSI main vent at 15:25 (local time) on 14 October 2011. Scale bar is determined using camera resolution, focal length, and distance from object. (b) Correlation of the OP‐FTIR signal peaks with explosive events (gray bars) detected from time‐lapse photography during a 30 min segment of the measurement period. Note that the time‐lapse photography signal matches the gas peaks with a 100 s delay, which corresponds to the time required for a gas plume to reach the instrument (assuming a wind speed of 5 m/s); this wind speed is in agreement with measured wind speed from a nearby weather station.

The initial tests on 16 October proved successful in allowing measurements of gas emissions from the mud volcano, and we carried out further measurements on 17 and 18 October. The greatest difficulty was the variable wind direction, which carried the plume off the original measurement axis. Moving the instruments and realigning them took between 20 and 30 min, which made following the plume challenging. Nevertheless, successful measurements were made, particularly on 17 October when a >2 h continuous data set was collected during an unvarying wind condition. A summary of analytical and environmental conditions during the 3 days of successful measurements is shown in the supporting information.

Temperature and relative humidity were measured with a handheld instrument (La Crosse Technology® WS‐9029U). OP‐FTIR spectra were collected at 0.5 cm−1 resolution (wave number), co‐adding between 8 and 16 spectra to produce each final spectrum. Each spectrum required between 15 and 30 s to collect. These features highlight a significant strength of the OP‐FTIR technique: relatively high frequency data collection that yields spectra containing information on the amounts of many different gas species (Figure 4). In addition, in May 2011, we carried out continuous temperature recordings using a S40 FLIR calibrated thermal camera, which uses an uncooled, 320 × 240 bolometer array and a single spectral band at 7–14 µm. This model has a sensitivity of 0.1°C, an accuracy of ±2°C, and 24° × 18° total field of view (which corresponds to a 1.3 mrad per pixel spatial resolution).

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Figure 4

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Time series of retrieved gas amounts measured with OP‐FTIR at LUSI on 16–18 October 2011. (a) Time series of CO2 and CH4 during two different sessions on 16 October 2011; the first used a path length of 55 m and the second a 155 m path length. (b) Time series of CH4 and CO2 during the longest session of 17 October 2011, with a path length of 223 m. (c) Time series of CH4, CO2, and NH3 on 18 October 2011, with a path length of 65 m.

2.1 Data Analysis

Spectra were analyzed using the FTIR_FIT software, an OP‐FTIR spectrum analysis package developed originally for high spectral resolution measurements of stratospheric gases [Burton, 1998] and subsequently optimized and improved for OP‐FTIR measurements of volcanic gases [e.g., Burton et al., 2000, 2007]. The retrieval of gas path length abundances is performed by fitting a calculated spectrum based on a forward model of the observed spectrum. Single‐beam spectra are analyzed, avoiding the need for a background spectrum, which is instead calculated implicitly during the fitting procedure, a process that is enabled by the sharp absorption lines that characterize such spectra. The forward model is based on the Reference Forward Model (available at http://www.atm.ox.ac.uk/RFM) and HITRAN database [Rothman et al., 1998], with additional functionality to adjust the instrument line shape, perform wavelength shifts, and add offsets. This model allows physically realistic spectra to be calculated. Fitting is performed using the optimal estimation approach and a Levenberg‐Marquardt nonlinear iteration [Rodgers, 2000].

FTIR_FIT works by selecting spectral windows where specific gases have absorption lines that can be used in the analysis step (supporting information Figure S1). An instrument line shape was calculated using 1.78 cm optical path difference, Norton‐Beer medium apodization and no field‐of‐view effect. Typical measured spectra, fitted spectra, and fit residuals for spectral windows corresponding to CO2, CH4, and NH3 are shown in supporting information Figure S1. Typical errors on retrieved gas amounts are ±5%, including fit errors, measurement errors, and forward model uncertainties. The units of the retrieval are path length concentrations (ppmv · m; i.e., parts per million by volume times path length).

3 Results

3.1 OP‐FTIR

LUSI gases detected by OP‐FTIR included CH4 and CO2, and occasionally NH3 and CO. Time series of path amounts (in units of ppmv) for CH4 and CO2 on 16 October 2011 are shown in Figure 4a. Both CO2 and CH4 occur naturally in the atmosphere, with typical concentrations of 390 ppmv and 1.8 ppmv, respectively; as a result, we observe a strong background signal (i.e., nonzero baseline concentrations) for these gases. Note, the two measurement sessions on 16 October were performed using different path lengths and the background concentrations retrieved are proportional to the differences in path length. All peaks exceeding background values in these time series are associated with gas emitted from LUSI. Path amounts for CO2 range from ∼20,000 ppmv · m (background, with a 55 m path length) to as much as ∼72,000 ppmv · m (155 m path length) and path length concentrations for CH4 range from ∼150 ppmv · m (background, 55 m path length) to ∼4500 ppmv · m (155 m path length); no NH3 was detected on the 16 October. Because CH4 peaks are up to a factor of 25 above background levels (CO2 peaks are only 10–20% above the background level), the OP‐FTIR retrieved amounts for CH4 are more sensitive than for CO2. In absolute terms, however, the amount of CO2 in the LUSI gas is greater than that of CH4 (Figure 5).

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Figure 5

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Correlation plots for gas path length concentrations measured with OP‐FTIR at LUSI on 16–17 October 2011. (a) CO2 (open circles) and CH4 (black diamonds) versus H2O for the second measurement session (15:30 to 15:45 local time) on 16 October 2011 (path length = 155 m). (b) CO2 (open circles) and CH4 (black diamonds) versus H2O for the longest measurement session on 17 October 2011 (path length = 223 m). Regression lines were calculated using a 2‐D total least squares, or Deming, method, with r being Pearson’s correlation coefficient. The data separation in CO2 values in Figure 5b is caused by drift in the background values during the course of the experiment (Figure 4b).

Correlation plots for CH4/H2O for the two sessions reveal ratios of 0.006 and 0.007, respectively; correlation plots for CO2/H2O reveal ratios of 0.013 and 0.021, respectively. These ratios correspond to an average mud gas CO2/CH4 molar ratio of 2.3 and 3.2 for the first and second measurement sessions, respectively. The overall composition of the LUSI mud gas (assuming it consisted exclusively of H2O, CO2, and CH4) is shown in Table 1.

Table 1. Composition of Gases Released During Explosive Bursts at the LUSI Mud Volcano, Derived From OP‐FTIR Measurementsa

 

Four sessions of measurements were conducted on 17 October, with the third session being the most successful. In this session, we collected 685 spectra over 2 h, virtually all of which included gas emissions from the mud explosions; time series for CO2 and CH4 from that session are shown in Figure 4b. There was some variability in the background concentration of CO2 (Figure 4b), and corresponding correlation plots for CO2, CH4, and H2O (Figure 5b) indicate a slightly greater degree of variability compared with that observed over a shorter time period on 16 October. The overall mud explosion gas composition was slightly more water‐rich on 17 October (Table 1).

One measurement session was conducted on 18 October, with good mud explosion gas detection only for the first 20 min. Results are shown in Figure 4c and Table 1. On this day, NH3 was detected with a modest correlation with the other mud explosion gases.

We detected carbon monoxide (CO) on most days, but it was impossible to unequivocally correlate CO with the other species, suggesting CO concentrations within the mud explosion gas were barely above those of ambient air at the point of measurement.

3.2 Observations of LUSI Explosion Frequency Activity

Parameters related to eruption cyclicity were measured using two different methods during the 23–27 May and 13–18 October campaigns. In May 2011, we used a FLIR S40 calibrated thermal camera, filming at 6 Hz, to determine each eruption’s duration and the duration of quiescent intervals between eruptions. In addition, we assumed the maximum temperature observed by the thermal camera was representative of the size or magnitude of each eruption. This assumption remains valid for several seconds after the start of each eruption, after which point steam often began obscuring the vent. Pixel‐integrated temperatures peaked at 74°C (Figure 6), which remains well below the near‐boiling mud eruption temperatures. We take this to be an artifact due to the large (1.4 × 1.4 m) pixel footprint that results when making FLIR measurements 1100 m away from LUSI’s main vent; each pixel contains both mud and ambient air, and the calibrated pixel temperature therefore represents a spatial average of the two temperatures. In October, we used time‐lapse high‐resolution digital photography, at a rate of 0.33 Hz to measure the interval between eruptions and eruption duration. The May and October 2011 FLIR and photography results are presented in supporting information S1.

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Figure 6

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Time series of the maximum pixel temperature observed at LUSI on 23 May 2011 with a FLIR thermal camera. Temperatures were recorded at 6 Hz, and the maximum pixel temperature is taken as a proxy for eruption intensity. The pixel size at 1100 m from the vent is 1.4 m.

The time interval between eruptions in May was, on average, 55 s (1σ = 23 s), whereas in October, the interval between eruptions was longer, 114 s (1σ = 41 s). Visual observations indicated each of these eruptions, or pulses, follows a similar pattern: they began with the emergence of a large mud bubble (Figure 3a) approximately 2–3 m in diameter, which quickly burst to send clots of the former bubble’s walls tens of meters into the air and release a large steam plume up to several hundred meters high. This initial bubble burst was followed by a rapid succession of smaller bubble bursts, which destabilized the ∼200 m diameter pool surrounding the vent area, causing hot mud to be ejected in 15–20 m high fountains above the vent. Corresponding steam condensation from the gas release shrouded the vent from further visual observation, but the audible noise from mud fountaining and gas emission indicated that eruptions lasted ∼15 s following the initial bubble burst. The ensuing quiescent phase was characterized by the liquid‐mud pool returning to stillness, and low‐level diffuse steaming from the pool. By 2011, LUSI had thus settled into a purely periodic state consisting of recurring explosions with intervening quiescent periods, exhibiting characteristic time scales on the order of minutes (very rarely exceeding 10 min). The mud appeared somewhat more viscous in 2011 than it did during our visit to LUSI in 2008. In 2008, our own visual observations indicated generally similar periodic activity, though perhaps with longer quiescent periods of up to 30 min and somewhat more diffuse gas bubbling at the main vent. Because of the similarities in overall eruption style and characteristic cycle periods in 2008 and 2011, we expect our results to be broadly applicable to a significant portion of the activity from 2008 to 2011.

4 Discussion

4.1 LUSI Mud Explosion Gas Compositions

Examining the background concentrations of the different gas species, we see good agreement between known and measured atmospheric abundances. During the first session on 16 October, our weather station measured a relative humidity of 52%, which corresponds to a water vapor partial pressure of 2.76 kPa (the saturated vapor pressure of water at 34°C is 5.3 kPa), close to the partial pressure of 2.86 kPa observed by FTIR (calculated as (pressure × ppmv · m)/(path length × 106)). The background CH4 was 99 ppmv · m, leading to an estimate of average concentration of 1.8 ppmv over the 55 m path length, in agreement with typical atmospheric methane concentrations. The measured background CO2 leads to a concentration estimate of 382 ppmv, similar to the average atmospheric CO2 concentrations of 385 ppmv measured in 2011 by a CO2 flask station in Indonesia [http://www.esrl.noaa.gov/gmd/dv/iadv/graph.php?code=BKT&program=ccgg&type=ts]. These measurements and calculations give us confidence that the measurements of the mud gas compositions are adequately accurate and precise, with less than 5% error on each species, typical for such measurements [Burton et al., 2000]. Similar agreement was found for measurement sessions on subsequent days.

The OP‐FTIR measurements conducted on LUSI mud volcano between 16 and 18 October 2011 successfully detected and quantified the gases emitted during the eruption bursts. The dominant characteristic of the gases emitted during mud volcanism at LUSI is that they are very rich in water vapor. Water vapor accounts for at least 96% of the total gas content. The CO2/CH4 molar ratio varied from session to session, ranging between 2.3 and 6.6 over the course of 4 days (Table 1), which is in line with values obtained by Mazzini et al. [2012] using a direct sampling method in six campaigns over 5 years. Assuming an invariant oxidation state, the CO2/CH4 ratio is controlled by pressure‐temperature conditions in the conduit, and therefore this variability probably reflects subtle changes in the subsurface gas‐fluid system.

Path length concentrations derived from OP‐FTIR data can be used to estimate how much gas is released in individual pulses, by integrating each gas path length concentration above background values for individual peaks. Assuming a plume with a half‐ellipse cross section approximately 200 m wide and 50 m high (in accordance with visual observations), and plume velocities of 6 m s−1 (as measured in the field), we estimate that a typical single eruptive pulse releases 2300 kg of H2O(g), 80 kg of CO2, and 5 kg of CH4 (cf. Table 1). Similarly, daily (Table 1) or yearly gas fluxes can be extrapolated from the integration of path length concentrations over a representative time series (lasting, in our case, 2 h on 17 October). Though the release of these gases to the atmosphere is relatively modest (2300 t yr−1 of CH4, on average), LUSI releases as much methane as a herd of ∼23,000 dairy cows (one head of cattle has been estimated to release ∼100 kg of methane per year [Schils et al., 2007; Cederberg et al., 2009])—albeit, only a fraction of the estimated amount of methane released by the ∼4.7 million heads of cattle in East Java [Kementan‐BPS, 2011]. On the other hand, a yearly methane flux of 1100–4400 t yr−1 (depending on an assumed plume geometry) at LUSI is two orders of magnitude higher than any existing estimate for individual mud volcanoes [Mörner and Etiope, 2002] and, by itself, is as much as 2% of the methane released by the entire mid‐ocean ridge system [Welhan and Craig, 1979].

4.2 Eruption Cycles

Based on time series analysis of thermal data (Figure 6), OP‐FTIR data, and photographic observations (supporting information S1), the mean duration of quiescence between bursts varied between 55 ± 23 s in May and 114 ± 41 s in October, and we note the distribution in duration values is not normal. A statistically significant correlation (Pearson’s correlation coefficient, r = 0.64, p < 0.001) exists between the duration of an eruption and the amplitude of the associated thermal signal (Figure 7). A weaker yet statistically significant correlation (r = 0.46, p = 0.007) exists between the duration of an eruption and the wait time (or lag) since the previous eruption. However, there is no correlation (p > 0.5) between the duration or intensity of a burst and the duration of the following quiescent period. Collectively these results indicate that more thermally intense bursts last longer; longer, more intense, bursts are preceded by longer wait times; and recovery time is not apparently controlled by the duration or intensity of the preceding burst. This third point suggests that, regardless of eruption duration or intensity, each eruption burst resets the system to a common starting point.

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Figure 7

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Correlation plots of eruptive burst timing and intensity parameters. (a) Burst duration and intensity; (b) burst duration and quiescent time interval since the last eruptive burst (lead time); (c) lead time and burst intensity. We consider p values < 0.05 to be statistically significant.

4.3 Eruption Processes

It is interesting to examine the LUSI explosive behavior in light of our knowledge of similar periodic explosions in magmatic systems, such as Stromboli, Italy. At Stromboli volcano, gases collect and coalesce on the way to the surface to form sequences of gas slugs that expand forming observable bubbles that burst as they arrive at the surface (Strombolian activity) [e.g., Blackburn et al., 1976; Ripepe et al., 2001; Chouet et al., 2003; Burton et al., 2007]. Such bursts occur a few times per hour. Some characteristics of LUSI’s periodic bursts resemble this type of activity: (1) similar bubble bursts, and bubble sizes [e.g., Blackburn et al., 1976; Braun and Ripepe, 1993; Vergniolle and Brandeis, 1996]; and (2) broadly similar time intervals between bursts [e.g., Settle and McGetchin, 1980]. Unsurprisingly, given the differences between the erupting systems, the composition of gas released from LUSI is quite different compared with that produced at Stromboli volcano (Table 1). Another important difference is the detailed timing of the degassing process. The bulk of gas released at Stromboli is emitted during the quiescent phases via passive degassing [Mori and Burton, 2009], whereas the bulk of the gas released at LUSI occurs during explosions and passive degassing is negligible (e.g., Figure 4). This difference suggests mechanistic differences between the two systems. For LUSI it appears that gas phases are concentrated in the large bubbles or slugs that can be observed bursting at the surface, and that the presence of small bubbles between slugs or alternate degassing pathways is unlikely or insignificant. Furthermore, we witnessed no surface oscillations that are indicative of churn flow. We therefore conclude that the flow regime can be classified as purely slug flow, rather than churn flow, bubbly flow or transitional between any two regimes [Taitel et al., 1980; Faghri and Zhang, 2006].

In the field of fluid dynamics, different flow regimes (including slug flow) have been reproduced experimentally for upward two‐phase flow of gas and liquid in a vertical tube, demonstrating that flow regimes are controlled by the relative and absolute flow rates of the gas and liquid phases [e.g., Hewitt and Roberts, 1969; Taitel et al., 1980; Hewitt, 1998; Thome, 2004]. Here for the purposes of understanding the system dynamics, we treat the mixture of gases within a bubble as a single gas phase and the well‐mixed water‐mud mixture as a single liquid phase. Given the behavior observed at LUSI and our basic mechanistic interpretation above, we attempt a quantitative assessment of flow rates at LUSI starting from our measured water vapor mass fluxes of 10–50 kg s−1 (see section 4.1, and Table 1), and assuming a range of water vapor densities (1–5 kg m−3), consistent with temperatures ranging from 100 to 150°C and pressures associated with mud‐static conditions at depths ranging from 10 to 50 m [mud density up to 1500 kg m−3, Mazzini et al., 2007; our measurements].

To this end, using generalized models for flow pattern transitions for upward gas‐liquid flow in vertical cylinders [Taitel et al., 1980], we constrain the maximum superficial liquid (mud‐water) velocity (volume flux/cylinder area) that is consistent with the observed slug flow and measured superficial gas velocities (volume flux/cylinder area; supporting information Figure S2). Aside from gas and liquid fluxes, the main controls on the bubbly to slug flow transition are liquid and gas densities and the liquid surface tension. In supporting information Figure S2, liquid and gas densities are as reported above, and the surface tension of the mud‐water mixture ranges from 0.044 to 0.072 N m−1 [Ambrose and Loomis, 1935]. This transition line is not strongly sensitive to surface tension or gas density, and thus one line is shown. The slug to churn flow transition is shown in the same figure and is controlled by the relative flow rates of liquid and gas, the cylinder/conduit diameter, and the nondimensional entrance length, defined as the length over which the flow evolves to the slug pattern divided by the cylinder diameter, where the length initiates where two‐phase flow begins. The depth of decompressional boiling for the LUSI system is constrained to ∼40 m (see below), and is taken as the initiation depth of two‐phase flow, while the cylinder diameter, based on bubble size, is approximately 3 m. Therefore, our maximum nondimensional entrance length is 13, and constrains the right‐most possible transition from slug to churn flow (supporting information Figure S2). The shaded region in the supporting information figure shows the range of liquid and gas superficial fluxes consistent with slug flow, and demonstrates a maximum liquid volumetric flux of 105 m3 d−1. The bubble ascent velocities (Taylor bubble rise) in this region are <2 m s−1, corresponding to bubble rise times of ∼30 s, reasonably consistent with the measured periodicity.

Although this water‐mud flux appears to be somewhat unconstrained, given that our estimates are simply consistent with the highest flow rates observed during the eruption, we can use this map to evaluate the behavior of the LUSI system. For example, if the superficial gas velocity were to increase, while remaining in the slug flow regime, evidenced by larger bursts with the same periodicity, the behavior may suggest a decrease in superficial liquid velocity defined by the right‐most line in the figure. A decrease in superficial gas velocity, again while still slug flow, may suggest an increase in liquid superficial velocity, with a maximum defined by the intersection of the two lines. Transitions to either bubble flow or churn flow indicate a decrease or increase in gas flux, respectively, but permit a wide range of liquid fluxes.

We now consider the gas phases in the system, in order to understand the depth of origin of the bubbles that dominate the dynamics of the slug flow system. Eruption bursts may be driven by rapid decompressional boiling of water, or exsolution of other gas species due to decompression during ascent. Thus, to aid understanding of the depth of origin of the bubbles in the system, we have calculated the depth of decompressional boiling for water, and the depth of exsolution for carbon dioxide and methane. To simplify calculations, we assume each case independently, which is reasonably justified because the presence of methane and carbon dioxide at these concentrations do not significantly affect the boiling point of water [Jarne et al., 2004; dos Ramos et al., 2007], nor do they significantly affect the solubility of one another in water at the inferred concentrations [Blount and Price, 1982; Spycher et al., 2003].

We calculate the depth of water vapor bubble formation by assuming the water ascends isothermally until it falls below its threshold boiling pressure. Assuming isothermal ascent of water for a range of temperatures between 100 and 150°C, consistent with in situ temperature measurements of the LUSI system [e.g., Mazzini et al., 2007; our own unpublished results], and a water‐mud mixture density between 1200 and 1500 kg m−3, the boiling depth lies between approximately 10 and 40 m below the surface. The discrepancy between the calculated rise time scale using bubble ascent velocity (30 s) and the observed time scale may be caused by the high viscosity and possible non‐Newtonian rheology of the mud‐water mixture.

We also consider the exsolution of CO2 and its role in producing a gas phase, as suggested by Lu et al. [2005] for geyser systems. The gas molar ratios measured by OP‐FTIR places constraints on the proportional abundance of CO2 (and methane) in the fluid system; if each bubble represents a mass of liquid water that has vaporized completely, then all dissolved gas (carbon dioxide and methane) is stripped into the vapor phase and the postboiling gas‐to‐gas ratio is representative of the preboiling dissolved gas content. At a given temperature, Henry’s law dictates the amount of a gas species that can be dissolved in a certain volume of liquid, based on the partial pressure of the gas in equilibrium with the liquid. The Henry’s Law coefficient KH,CO2 was calculated for a range of temperatures using the relationship suggested by Crovetto [1991] for temperatures above 80°C. The values for KH,CO2 vary between 94.4 atm L/mol at 100°C and 109.1 atm L/mol at 150°C. For temperatures of 100–150°C and water‐mud mixture density of 1500 kg m−3, a CO2/H2O molar ratio of 0.02 (Figure 5a) suggests that CO2 exsolves from the water at pressures of ∼12 MPa and lower, which corresponds to nucleation depths between ∼700 and 1000 m. We perform the corresponding calculation for methane (CH4/H2O molar ratio of 0.006; 2480 atm L/mol ≤ KH,CH4 ≤ 4250 atm L/mol) and find that methane bubbles nucleate at depths of 5000–9000 m, suggesting that methane bubbles exist at depth within the system, likely even below the clay source region in the Upper Kalibeng Formation at 1000–2000 m depth [e.g., Sutriono, 2007; Tingay et al., 2008]. A schematic view of the subsurface plumbing system and processes is shown in Figure 8.

LOYC2014-8

Figure 8

Open in figure viewerPowerPoint

Conceptual model of gas transport in the LUSI mud volcano. In this model, methane gas is present several thousand meters below the surface, including at the 1800–1300 m mudstone interval where the mud’s solid fraction is thought to originate [e.g., Mazzini et al., 2007]. CO2 exsolves 600–1000 m below the surface, but the total mass flux of methane and carbon dioxide is insufficient to self‐organize into large gas slugs. At depths of 10–40 m, the hot water in the mud begins to boil, at which point the large volume of water vapor can coalesce into gas slugs that rise to the surface every few minutes, where they burst and cause the cyclical mud fountaining events observed at the main vent.

Given that both CO2 and methane form bubbles deeper than the depth of decompressional boiling for water (the dominant gas phase), we performed tests to examine whether or not the abundance of methane, CO2, or the combination of the two gases at >50 m depth is consistent with slug flow conditions. The corresponding superficial gas velocities are insufficient to result in slug flow, given the framework discussed above, and should produce bubble flow [Taitel et al., 1980; Faghri and Zhang, 2006] (supporting information Figure S2). We therefore conclude that decompressional boiling of water, and coincident gas stripping, initiates slug flow, which then dominates the observed shallow dynamics.

However, our solubility calculations do suggest that methane is in the gas phase in the mud source region (1000–2000 m), which may have some bearing on large‐scale dynamics, in that bubbles may strongly affect mixture density, compressibility, and rheology. Any further work using models of fluid ascent based on conservation equations should account for these factors when predicting future mass flow rates and eruption longevity.

Acknowledgments

We thank Badan Penanggulangan Lumpur Sidoarjo (BPLS) for providing generous field help and access to the LUSI site, and particularly Pak Hardi Prasetyo and Pak Soffian Hadi Joyopranoto. We are grateful to an anonymous reviewer for helpful comments. We thank S. Carn for lending us an IR source, R. Wright for use of a FLIR, G. Marliyani for help in the field, and T. Esposti Ongaro for helpful discussions. We also acknowledge the Exploration Postdoctoral Fellowship program at ASU and the Bakrie Initiative in Geological Hazards at ASU (funded by Minarak Labuan Co.) for financial support. We report no conflict between our scientific objectives and the interests of our funding sources.

References

Gempa Madura – Lebaran 2018: Postur dan Perilaku Geyser Lusi

Juni 17, 2018

 

KETIKA LUSI IKUT BERLEBARAN
DENGAN POSTUR DAN PERILAKU SEMBURAN YANG INDAH DAN BERTENAGA

Slide1

Drone diambil Saat Lebaran Hari Jumat Jam  15.25 WIB

Pilot Drone: Adang, Petugas Lapangan PPLS

Yang mendapatkan antusias dari Tamu Yang Berlebaran di LUSI

Slide2

Ringkasan Perubahan Postur Lusi dari 24 Mei

dan Lebaran 15 Juni 2018 (Drone, Adang)

Slide27

00DRONEJUNI2018x.jpg

Benchmarking Postur Geyser Lusi 24 Agustus 2017 (Satelit, Google Earth), 24 Mei 2018 (Drone PPLS), Foto 7 Juni 2018 (Adang, PPLS).

POSTUR LUSI PADA LEBARAN 15 JUNI 2018
Pasca Gempabumi Sumenep,Madura 14 Juni 2018

BMKG : Gempa Bumi di Sumenep Tak Berpotensi Tsunami

Sumenep, (Media Madura) – Kepala Balai Besar MKG Wilayah III Denpasar Bali, M. Taufik Gunawan melalui BMKG Kalianget menyatakan, gempa yang mengguncang wilayah Kabupaten Sumenep, Madura, Jawa Timur tidak berpotensi tsunami.

Gempa tektonik terjadi Hari Rabu (13/6/2018) pukul 20.06.40 WIB, di wilayah di sekitar Sumenep. Sebagian besar masyarakat merasakan gempa yang cukup dahsyat tersebut hingga berhamburan keluar rumah.

Hasil analisis BMKG terbaru menunjukkan, bahwa gempa bumi ini berkekuatan M 4,8, dengan episenter pada koordinat 6,88 LS dan 113,94 BT, tepatnya di darat pada jarak sekitar 6 km arah Timur Laut Sumenep dengan kedalaman 12 kilometer.

Sumber: https://mediamadura.com/2018/06/13/bmkg-gempa-bumi-di-sumenep-tak-berpotensi-tsunami/Slide12.JPGSlide6

CATATAN POSTUR LUSI PADA LEBARAN 15 JUNI 2018 UNTUK MENJADIKAN PERHATIAN:Slide6

  • Dalam kurun waktu sekitar tiga minggu (23 Mei-15 Juni) dapat diamati terjadinya perubahan terkait Postur dan Perilaku Geyser Sulung-dan Bungsu yang sudah semakin permanen;
  • Rekaman citra drone dapat merekam siklus semburan dianara Geyser Sulung dan Bungsu, dimana secara umum Sulung dari beberapa aspek menjadi Dominan.
  • Saluran utara-selatan dibatasi kelurusan patahan, telah diisi oleh lumpur pekat. Pada citra Drone juga menunjukkan kelurusan membatasi Kawah Bungsu;

Slide7.JPG

Postur Geyser Sulung dan Bungsu dari timurlaut, memperlihatkan aktivitas geysering uap air, Dominan Sulung, aliran melalui saluran depresi arah utara-selatan dengan kelurusan utara-selatan (Patahan).

Slide9.JPG

  • Dapat diamati aliran lumpur panas (pengamatan lapangan) encer baik kearah barat laut, dan utara yang menembus Berm di Zona Nirwana.

Slide14.JPG

Bungsu dengan Geysering uap air, limpasan breksi lumpur pekat warna hitam yang dilontarkan secara “mud kick” di depannya lumpur-air panas kearah baratlaut.

  • Walaupun terjadi perubahan cukup signifikan, namun tidak dapat disimpulkan ada pengaruh langsung dari kejadian Gempa Sumeneb-Madura. Berbeda ketika perubahan Lusi pasca gempabumi Pacitan dan Jawa Barat yang didukung tambahan informasi dan pemaknaan hubungan Lusi dengan dinamika busurdepan (forearc).

Slide16.JPG

Evaluasi Postur dan Perilaku Semburan Geyser Lusi: Pasca Gempa Madura, Pada Lebaran 2017

  • 14 Juni 2018 terjadi gempabumi dengan Pusat Gempa di Sumeneb, Pulau Madura, menurut BMKG merupakan gempa intra-lempeng (intra plate earthquake), pusat gempa di darat, kedalaman yang dangkal.
  • Pelajaran dari kejadian gempabumi terjadi di Selatan Jawa dengan mekanisme “mega thrust” subduksi Lempeng yaitu Pacitan dan Jawa Barat, telah memberikan implikasi pada Postur dan Perilaku Semburan Geyser Lusi yang mengalami dinamika yang signifikan namun temporer. Testimoni direkam dengan Drone.

Slide13.JPG

Postur Geyser Lusi yang dominan, masih memperlihatkan mud kick

  • Atas pengalaman tersebut, pasca gempa Sumenep saya menanyakan kepada teman Lapangan di PPLS, mungkin ada perubahan, walaupun menurut teori, kemungkingannya kecil pengaruhnya pada Lusi.
  • Bersyukur pada hari Lebaran, Jumat 15 Juni 2018, Adang dari PPLS sebagai pilot telah menerbangkan Drone sekitar Jam 15.15 Wib dan merekam foto dan Video.

 

Slide21.JPG

  • Menarik karena berdasarkan benchmarking Citra Drone 23 dan 24 Mei 2018 sebagai pembanding terlihat jelas terjadi suatu perubahan, yang menyolok.
  • Perilaku Geyser Lusi Sulung dan Bungsu sangat aktif, terekam dengan mengeluarkan breksi lumpur pekat.

Slide23.JPG

 

  • Pandangan dari arah utara dan barat menunjukkan pada Kawah Geyser Sulung yang dominan, di bagian utaranya berkembang saluran memanjang arah utara-selatan. Aktualisasi dari Citra 24 Juni.
  • Zoom Saluran tersebut terlihat sangat jelas berkembangnya bidang kelurusan utara-selatan yang dapat disebut Patahan?

Slide28.JPG

Kelurusan Postur Saluran Sulung  di utara Kawah Sulung dan Postur Punggungan Siring. Postur Geyser Sulung di tenggara dan Bungsu di baratlaut dengan limpasan lumpur cair panas ke barat laut.

 

Perbandingan Album Citra Drone

Slide32

November 2015 (Badan Geologi), 3 Mei dan 24 Mei 2018 (PPLS)

Slide36

Slide37

Testimoni Perubahan Postur Lusi pasca Gempabumi Jawa Barat. Semburan menjadi tiga dengan semburan “Jet Steam”, Geyser Bungsu mengalami masa tidur “dormant” selama ~25 menit.

Slide33

Slide35

Sangat aktif Geysering klastik (breksi lumpur) pekat warna Hitam, Geyser  Sulung dominan

 

 

Membangun Ketahan menghadapi Bencana: Deklarasi Hyogo 2005-2015

Juni 13, 2018

TINJAUAN terhadap Deklarasi Hyogo (Hyogo Declaration)

Oleh: DR. Hardi Prasetyo

Mantan Pimpinan Badan Penanggulangan Lumpur Sidorjo (BPLS) 2007-2017, Sepuluh Tahun Mengasuh Lusi, suatu Pelajaran Berharga dari Bencana semburan mud volcano di Indonesia dan Dunia.

UN Documents  Gathering a body of global agreements

Pengantar:

Dokumen ini ditinjau sebagai salah atu upaya memahami Paradigma Baru Pengurangan Risiko Bencana Global, khususnya lebih memaknai Deklarasi Hygo yang telah menghasilkan suatu Kerangka kerja Hyogo 2005-2015: Membangun Ketahanan Bangsa dan Masyarakat terhadap Bencana “Hyogo Framework for Action 2005: Building the Resilience of Nations and Communities to Disasters”.

Dokumen Perserikatan Bangsa-bangsa telah dikompilasi oleh the NGO Committee  on Education of the Conference of NGOs from United Nations web site.

Dokumen  ini merupakan bagian awal dari dokumen KERANGKA KERJA SENDAI Untuk Pengurangan Risiko Bencana 2015-2030.

Suatu hal yang menjadi catatan terkait Kebencaan Geologi di Indonesia adalah pada tahun 2017 Jurnal Geological Society of London (GSL) telah mempublikasikan Edisi Khusus “BAHAYA GEOLOGI DI INDONESIA: ILMU KEBUMIAN UNTUK PENGURANGAN RISIKO BAHAYA”.

Salah satu aspek Geohazard yang diangkat adalah terkait dengan Semburan mud volcano Lusi, dengan Judul “Memahami pemicu semburan LUSI mud volcano dari tanda-tanda deformasi tanah” Understanding the trigger for the LUSI mud volcano eruption from ground deformation signatures

andreas2017-1

Himpunan dari koleksi “Geyser Lusi Library&Virtual Museum 2018”.

Ilmu, pengetahuan dan Pengalaman terkait Kebencaan Lusi untuk diamalkan.

Hardi Prasetyo

geyserlUsi2018

Sumber: http://www.thewaterchannel.tv/tutorial/en/section_5/4.html

10 Tahun Mengasuh Lusi, suatu Bencana mud volcano yang terunik terbesar di Dunia, penuh ketidak pastian baik dari sisi pengendali mekanisme maupun Penanggulangan Bencana yang bersifat berulang dari siklus bencana yang umum.

Kerangka Kerja Hyogo 2005-2015: Membangun Ketahanan Bangsa dan Masyarakat terhadap Bencana

Hyogo Framework for Action 2005-2015: Building the Resilience of Nations and Communities to Disasters

https://www.slideserve.com/erin-rosales/united-nations-international-strategy-for-disaster-reduction-un-isdr-unisdr

 

Pada pertemuan pleno ke-9, pada 22 Januari 2005, Konferensi Dunia tentang Pengurangan Bencana telah mengadopsi Deklarasi Hyogo, yang berbunyi sebagai berikut:

At its 9th plenary meeting, on 22 January 2005, the World Conference on Disaster Reduction adopted the Hyogo Declaration, which reads as follows:

Deklarasi Hyogo

Kami, delegasi pada Konferensi Dunia tentang Pengurangan Bencana, telah berkumpul dari 18 hingga 22 Januari 2005 di Prefektur Hyogo, Prefektur Kobe, Jepang, yang telah menunjukkan pemulihan yang luar biasa dari bencana Gempa Bumi Besar Hanshin-Awaji, yang terjadi 17 Januari 1995.

We, delegates to the World Conference on Disaster Reduction, have gathered from 18 to 22 January 2005 in Kobe City of Japan’s Hyogo Prefecture, which has demonstrated a remarkable recovery from the Great Hanshin-Awaji Earthquake of 17 January 1995.

Kami menyampaikan belasungkawa dan simpati kami yang tulus kepada, dan solidaritas, dengan rakyat dan masyarakat yang dirugikan oleh bencana, terutama mereka yang porak poranda oleh bencna gempa bumi dan tsunami yang belum pernah terjadi sebelumnya di Samudera Hindia pada 26 Desember 2004.

We express our sincere condolences and sympathy to, and solidarity with, the people and communities adversely affected by disasters, particularly those devastated by the unprecedented earthquake and tsunami disaster in the Indian Ocean on 26 December 2004.

Kami juga memuji terhadap upaya yang telah dilakukan oleh mereka, PemerintahNya dan komunitas internasional untuk merespon dan mengatasi tragedi ini.

Sebagai tindaklanjut dari  Pertemuan Khusus para Pimpinan dari Asosiasi Negara-negara Asia Tenggara pasca Bencana Gempa Bumi dan Tsunami, yang diadakan di Jakarta pada tanggal 6 Januari 2005, kami berkomitmen untuk membantu mereka, termasuk dengan menghormati/apresiasi terhadap langkah-langkah yang tepat terkait dengan pengurangan bencana.

We commend the efforts made by them, their Governments and the international community to respond to and overcome this tragedy. In response to the Special Leaders’ Meeting of the Association of South-East Asian Nations on the Aftermath of Earthquake and Tsunami, held in Jakarta on 6 January 2005, we commit ourselves to assisting them, including with respect to appropriate measures pertinent to disaster reduction.

Kami juga percaya bahwa pembelajaran dari bencana ini relevan dengan daerah-daerah lainnya. Dalam hubungan ini, sesi khusus mengenai bencana gempa dan tsunami yang baru-baru ini diadakan ada Konferensi Dunia untuk meninjau kembali bencana itu dari perspektif pengurangan risiko.

Selanjutnya menyampaikan Pernyataan Umum dari Sesi Khusus tentang Bencana Samudra HIndia (Indian Ocean Disaster): Pengurangan Risiko untuk Masa Depan yang Lebih Aman dan outcome yang dihasilkan (Risk Reduction for a Safer Future as its outcome)

We also believe that lessons learned from this disaster are relevant to other regions. In this connection, a special session on the recent earthquake and tsunami disaster, convened at the World Conference to review that disaster from a risk reduction perspective, delivered the Common Statement of the Special Session on Indian Ocean Disaster: Risk Reduction for a Safer Future as its outcome.

 

Kami menyadari bahwa masyarakat internasional telah menghimpun banyak pengalaman dalam  pengurangan risiko bencana melalui Dekade Internasional untuk Pengurangan Bencana Alam yang dilanjutkan dengan Strategi Internasional Pengurangan Bencana Internasional.

We recognize that the international community has accumulated much experience with disaster risk reduction through the International Decade for Natural Disaster Reduction and the succeeding International Strategy for Disaster Reduction.

Secara khusus, dengan mengambil langkah-langkah konkret yang sejalan dengan Strategi dan Rencana Aksi Yokohama untuk Dunia yang Lebih Aman, kami telah banyak belajar, termasuk tentang kesenjangan dan tantangan sejak Konferensi Yokohama tahun 1994.

In particular, by taking concrete measures in line with the Yokohama Strategy and Plan of Action for a Safer World, we have learned much, including about gaps and challenges since the 1994 Yokohama Conference.

Namun demikian, kami secara mendalam sangat prihatin bahwa masyarakat terus mengalami kerugian yang berlebihan dari sendi kehidupan manusia dan properti yang bernilai  serta yang mengalami cedera yang serius dan juga terjadinya pengungsian yang besar karena berbagai bencana di seluruh dunia.

Nevertheless, we are deeply concerned that communities continue to experience excessive losses of precious human lives and valuable property as well as serious injuries and major displacements due to various disasters worldwide.

Kami yakin bahwa bencana secara serius telah merusak trehadap hasil-hasil investasi pembangunan dalam waktu yang sangat singkat, dan oleh karena itu, tetap menjadi penghambat utama dari pembangunan berkelanjutan dan pengentasan kemiskinan.

We are convinced that disasters seriously undermine the results of development investments in a very short time, and therefore, remain a major impediment to sustainable development and poverty eradication.

Kami juga menyadari bahwa investasi pembangunan yang gagal dalam mempertimbangkan risiko bencana secara tepat, dapat meningkatkan kerentanan.

We are also cognizant that development investments that fail to appropriately consider disaster risks could increase vulnerability.

Mengatasi dan dengan mengurangi bencana sehingga memungkinkan dan memperkuat bangsa-bangsa pada pembangunan berkelanjutan, oleh karena itu, merupakan salah satu tantangan paling kritis yang dihadapi komunitas internasional.

Coping with and reducing disasters so as to enable and strengthen nations’ sustainable development is, therefore, one of the most critical challenges facing the international community.

Kami bertekad untuk mengurangi kerugian korban jiwa dan asset-aset sosial, ekonomi dan lingkungan lainnya di seluruh dunia, disamping itu sadar akan pentingnya kerjasama internasional, solidaritas dan kemitraan, serta tata pemerintahan yang baik di semua tingkatan.

Kami menegaskan kembali peran penting dari sistem Perserikatan Bangsa-Bangsa dalam pengurangan risiko bencana.

We are determined to reduce disaster losses of lives and other social, economic and environmental assets worldwide, mindful of the importance of international cooperation, solidarity and partnership, as well as good governance at all levels.

 We reaffirm the vital role of the United Nations system in disaster risk reduction.

Dengan demikian, kami mendeklarasikan hal-hal sebagai berikut:

Thus, we declare the following:

  1. Kami akan membangun berdasarkan komitmen dan kerangka kerja internasional yang relevan, serta tujuan pembangunan yang disepakati secara internasional, termasuk yang terkandung dalam Deklarasi Milenium, untuk memperkuat kegiatan pengurangan bencana global untuk abad ke-21.

We will build upon relevant international commitments and frameworks, as well as internationally agreed development goals, including those contained in the Millennium Declaration, to strengthen global disaster reduction activities for the twenty-first century.

Bencana memiliki dampak merugikan yang luar biasa terhadap upaya-upaya di semua tingkatan untuk mengentaskan kemiskinan global; dampak bencana tetap menjadi tantangan yang signifikan bagi pembangunan berkelanjutan.

Disasters have a tremendously detrimental impact on efforts at all levels to eradicate global poverty; the impact of disasters remains a significant challenge to sustainable development.

  1. Kami mengakui hubungan yang mendalam antara pengurangan bencana, pembangunan berkelanjutan dan pengentasan kemiskinan, diantaranya, dan pentingnya melibatkan semua pemangku kepentingan, termasuk pemerintah, organisasiorganisasi regional dan internasional dan lembaga-lembaga keuangan, masyarakat sipil, termasuk organisasi non-pemerintah dan relawan, sektor swasta dan komunitas ilmiah.

We recognize the intrinsic relationship between disaster reduction, sustainable development and poverty eradication, among others, and the importance of involving all stakeholders, including governments, regional and international organizations and financial institutions, civil society, including non-governmental organizations and volunteers, the private sector and the scientific community.

Karena itu kami menyambut semua kegiatan yang relevan yang terjadi dan kontribusi yang dibuat selama Konferensi dan proses-proses persiapannya.

We therefore welcome all the relevant events that took place and contributions made in the course of the Conference and its preparatory process.

  1. Kami juga mengakui bahwa suatu budaya puntuk encegahan dan ketahanan bencana, dan strategi-strategi pra-bencana yang terkait, yang merupakan merupakan suatu investasi yang sehat, harus dipupuk di semua tingkatan, mulai dari tingkatan individu hingga ke tingkat internasional.

We recognize as well that a culture of disaster prevention and resilience, and associated pre-disaster strategies, which are sound investments, must be fostered at all levels, ranging from the individual to the international levels.

Masyarakat manusia harus hidup dengan risiko bahaya yang ditimbulkan oleh alam. Namun, kita masih jauh dari tidak berdayaan untuk persiapan dan mitigasi terhadap dampak bencana. Kita dapat dan harus mengurangi penderitaan dari bahaya dengan mengurangi kerentanan masyarakat.

Human societies have to live with the risk of hazards posed by nature.

However, we are far from powerless to prepare for and mitigate the impact of disasters. We can and must alleviate the suffering from hazards by reducing the vulnerability of societies.

  1. Kami juga mengakui bahwa suatu budaya puntuk encegahan dan ketahanan bencana, dan strategi-strategi pra-bencana yang terkait, yang merupakan merupakan suatu investasi yang sehat, harus dipupuk di semua tingkatan, mulai dari tingkatan individu hingga ke tingkat internasional.

We recognize as well that a culture of disaster prevention and resilience, and associated pre-disaster strategies, which are sound investments, must be fostered at all levels, ranging from the individual to the international levels.

Masyarakat manusia harus hidup dengan risiko bahaya yang ditimbulkan oleh alam. Namun, kita masih jauh dari tidak berdayaan untuk persiapan dan mitigasi terhadap dampak bencana. Kita dapat dan harus mengurangi penderitaan dari bahaya dengan mengurangi kerentanan masyarakat.

Human societies have to live with the risk of hazards posed by nature.

However, we are far from powerless to prepare for and mitigate the impact of disasters. We can and must alleviate the suffering from hazards by reducing the vulnerability of societies.

Kita dapat dan harus semakin membangun ketahanan bangsa dan masyarakat terhadap bencana melalui sistem peringatan dini yang basis pada masyarakat, penilaian risiko, pendidikan dan pendekatan dan kegiatan lainnya yang proaktif, terintegrasi, multi-bahaya, dan pendekatan dan aktivitas multi-sektoral dalam konteks pengurangan siklus bencana, yang terdiri dari pencegahan, kesiapsiagaan, dan tanggap darurat, serta pemulihan dan rehabilitasi (of prevention, preparedness, and emergency response, as well as recovery and rehabilitation).

We can and must further build the resilience of nations and communities to disasters through people-centered early warning systems, risks assessments, education and other proactive, integrated, multi-hazard, and multi-sectoral approaches and activities in the context of the disaster reduction cycle, which consists of prevention, preparedness, and emergency response, as well as recovery and rehabilitation.

Risiko-resiko bencana, bahaya-bahaya, dan dampaknya menimbulkan ancaman, tetapi respon yang tepat terhadap hal ini dapat dan harus mengarah pada tindakan untuk mengurangi risiko dan kerentanan di masa depan.

Disaster risks, hazards, and their impacts pose a threat, but appropriate response to these can and should lead to actions to reduce risks and vulnerabilities in the future.

  1. Kami menegaskan bahwa Negara memiliki tanggung jawab utama untuk melindungi jiwa dan properti dari berbagai bahaya di wilayah mereka, dan dengan demikian, menjadi urgen untuk memberikan prioritas tinggi pada pengurangan risiko bencana dalam kebijakan nasional, konsisten dengan kapasitas mereka dan sumber daya yang tersedia bagi mereka.

We affirm that States have the primary responsibility to protect the people and property on their territory from hazards, and thus, it is vital to give high priority to disaster risk reduction in national policy, consistent with their capacities and the resources available to them.

Kami setuju bahwa penguatan kapasitas tingkat masyarakat untuk mengurangi risiko bencana di tingkat lokal sangat diperlukan, mengingat bahwa langkah-langkah pengurangan bencana yang tepat pada tingkat itu memungkinkan masyarakat dan individu untuk mengurangi kerentanan mereka terhadap bahaya secara signifikan.

We concur that strengthening community level capacities to reduce disaster risk at the local level is especially needed, considering that appropriate disaster reduction measures at that level enable the communities and individuals to reduce significantly their vulnerability to hazards.

Bencana tetap menjadi ancaman utama bagi kelangsungan hidup, martabat, penghidupan dan keamanan masyarakat dan masyarakat, khususnya kaum miskin.

Disasters remain a major threat to the survival, dignity, livelihood and security of peoples and communities, in particular the poor.

Oleh karena itu ada kebutuhan mendesak untuk meningkatkan kapasitas negara-negara berkembang yang rawan bencana, khususnya negara-negara paling terbelakang dan negara-negara kepulauan kecil yang sedang berkembang, untuk mengurangi dampak bencana

Melalui perkuatan upaya-upaya nasional dan meningkatkan kerja sama bilateral, regional dan internasional, termasuk melalui bantuan teknis dan keuangan.

Therefore there is an urgent need to enhance the capacity of disaster-prone developing countries in particular, the least developed countries and small island developing States, to reduce the impact of disasters.

Through strengthened national efforts and enhanced bilateral, regional and international cooperation, including through technical and financial assistance.

5.Oleh karena itu Kami mengadopsi, Kerangka Kerja Hyogo 2005-2015: Membangun Ketahanan Bangsa dan Masyarakat terhadap Bencana dengan nilai tambah yang diharapkan, sasaran strategis, dan prioritas untuk tindakan, serta strategi implementasi dan tindak lanjut terkait, sebagai kerangka pemandu untuk dekade berikutnya tentang pengurangan bencana.

We, therefore, adopt, the Hyogo Framework for Action 2005-2015: Building the Resilience of Nations and Communities to Disasters with its expected outcome, strategic goals, and priorities for action, as well as implementation strategies and associated follow-up, as a guiding framework for the next decade on disaster reduction.

  1.  Kami percaya menjadi sangat penting bahwa Kerangka Aksi Hyogo 2005-2015: Membangun Ketahanan Bangsa dan Komunitas untuk Bencana selanjutnya diterjemahkan ke dalam tindakan nyata di semua tingkatan dan bahwa pencapaian ditindaklanjuti melalui Strategi Internasional dalam rangka Pengurangan Bencana, untuk mengurangi risiko dan kerentanan bencana.

We believe that it is critically important that the Hyogo Framework for Action 2005-2015: Building the Resilience of Nations and Communities to Disasters be translated into concrete actions at all levels and that achievements are followed up through the International Strategy for Disaster Reduction, in order to reduce disaster risks and vulnerabilities.

Kami juga mengakui perlunya mengembangkan indicator-indikator untuk memantau kemajuan kegiatan pengurangan risiko bencana yang sesuai dengan keadaan dan kapasitas khusus.

Sebagai bagian dari upaya untuk mewujudkan outcome yang diharapkan dan sasaran strategis yang ditetapkan dalam Kerangka Kerja Hyogo 2005-2015: Membangun Ketahanan Bangsa Bangsa dan Komunitas untuk Bencana.

We also recognize the need to develop indicators to track progress on disaster risk reduction activities as appropriate to particular circumstances and capacities as part of the effort to realize the expected outcome and strategic goals set in the Hyogo Framework for Action 2005-2015: Building the Resilience of Nations and Communities to Disasters.

Kami menekankan pentingnya memperkuat interaksi kerjasama dan sinergis di antara berbagai pemangku kepentingan dan mempromosikan kemitraan berbasis sukarela untuk pengurangan bencana.

We underscore the importance of strengthening cooperative and synergistic interactions among various stakeholders and promoting voluntary partnerships for disaster reduction.

Kami juga memutuskan untuk mengembangkan lebih lanjut mekanisme berbagi informasi mengenai program, inisiatif, praktik terbaik, pelajaran yang dipetik, dan teknologi untuk mendukung pengurangan risiko bencana sehingga komunitas internasional dapat berbagi hasil-hasil dan kemanfaatan dari upaya ini.

We also resolve to further develop information sharing mechanisms on programmes, initiatives, best practices, lessons learnt and technologies in support of disaster risk reduction so that the international community can share the results of and benefits from these efforts.

  1. Kami sekarang menyerukan tindakan-tindakan dari semua pemangku kepentingan, mencari kontribusi-kontribusi dari mereka dengan kompetensi dan pengalaman spesifik yang relevan, menyadari bahwa realisasi hasil dari Konferensi Dunia bergantung pada upaya kolektif kita yang tanpa henti dan tak kenal lelah.

Serta adanya suatu kemauan politik yang kuat,  dan   suatu pembangian tanggung jawab bersama dan investasi, untuk membuat dunia yang lebih aman dari risiko bencana dalam dekade berikutnya untuk kepentingan generasi sekarang dan mendatang.

We now call for action from all stakeholders, seeking the contributions of those with relevant specific competences and experiences, aware that the realization of the outcomes of the World Conference depends on our unceasing and tireless collective efforts, and a strong political will, as well as a shared responsibility and investment, to make the world safer from the risk of disasters within the next decade for the benefit of the present and future generations.

  1. Kami menyampaikan penghargaan kami yang paling dalam kepada Pemerintah dan masyarakat Jepang yang telah bertindak sebagai tuan rumah dari Konferensi Dunia tentang Pengurangan Bencana, dan terima kasih khususnya orang-orang dari Prefektur Hyogo untuk keramahan mereka.

Kerangka Kerja Hyogo 2005-2015: Membangun Ketahanan Bangsa dan Masyarakat terhadap Bencana

We express our most profound appreciation to the Government and people of Japan for hosting the World Conference on Disaster Reduction, and thank particularly the people of Hyogo Prefecture for their hospitality.

Hyogo Framework for Action 2005-2015: Building the Resilience of Nations and Communities to Disasters

LAMPIRAN

Konferensi Dunia untuk Pengurangan Bencana10 Tahun Kerangka Kerja Hyogo datang dari Konferensi Dunia yang diadakan di Kobe, Hyogo, Jepang, dari 18 hingga 22 Januari 2005.

Kerangka Kerja Hyogo 2005-2015:

Membangun Ketahanan Bangsa dan Masyarakat terhadap Bencana (HFA) merupakan suatu rencana pertama untuk menjelaskan, menguraikan dan rincian kegiatan yang diperlukan dari semua para sektor dan aktor yang berbeda untuk mengurangi kerugian-kerugan dari bencana. 

The Hyogo Framework for Action 2005-2015:

Building the Resilience of Nations and Communities to Disasters (HFA) is the first plan to explain, describe and detail the work that is required from all different sectors and actors to reduce disaster losses.

HFA  dikembangkan dan disepakati oleh  banyak mitra yang diperlukan untuk mengurangi risiko bencana  yaitu: pemerintah, lembaga internasional, para ahli bencana dan banyak lainnya untuk menyatukannya mereka ke dalam suatu sistem koordinasi yang umum. 

it was developed and agreed on with the many partners needed to reduce disaster risk – governments, international agencies, disaster experts and many others – bringing them into a common system of coordination.

HFA telah meringkas lima prioritas untuk tindakan, dan menawarkan prinsip-prinsip panduan dan pemahaman yang praktis untuk pecapaian suatu tingkat terhadap ketahanan bencana.

The HFA outlines five priorities for action, and offers guiding principles and practical means for achieving disaster resilience.

Tujuannya adalah untuk secara meyakinkan dapat mengurangi kerugian dari bencana pada tahun 2015, dengan membangun suatu ketahanan dari negara dan masyarakat terhadap bencana. 

Its goal is to substantially reduce disaster losses by 2015 by building the resilience of nations and communities to disasters.

Hal ini mengandung makna akan mengurangi korban jiwa dan aset sosial, ekonomi, dan lingkungan ketika bahaya menyerang.

This means reducing loss of lives and social, economic, and environmental assets when hazards strike.

Its goal is to substantially reduce disaster losses by 2015 by building the resilience of nations and communities to disasters.

Prioritas Aksi 1:

Pastikan bahwa pengurangan risiko bencana merupakan prioritas nasional dan lokal dengan berbasis suatu kelembagaan yang kuat untuk implementasiya.

Priority Action 1: Ensure that disaster risk reduction is a national and a local priority with a strong institutional basis for implementation.

Negara-negara yang mengembangkan kerangkakerja kebijakan, legislatif dan kelembagaan untuk pengurangan risiko bencana dan yang mampu mengembangkan dan memantau kemajuan melalui indikator-indikator spesifik yang terukur, memiliki kapasitas yang lebih besar untuk mengelola risiko-risika dan untuk mencapai konsensus yang lebih luas untuk keterlibatan dan kepatuhan terhadap langkah-langkah pengurangan risiko bencana pada semua lintas sector dari masyarakat.

Countries that develop policy, legislative and institutional frameworks for disaster risk reduction and that are able to develop and track progress through specific and measurable indicators have greater capacity to manage risks and to achieve widespread consensus for, engagement in and compliance with disaster risk reduction measures across all sectors of society

Priority Action 2: Identifikasi, kaji dan monitor risiko bencana dan tingkatkan peringatan dini.

Priority Action 2: Identify, assess and monitor disaster risks and enhance early warning.

Titik awal untuk mengurangi risiko bencana dan untuk mempromosikan suatu budaya terhadap ketahanan bencana, terletak pada pengetahuan tentang bahaya, serta kerentanan pada aspek-aspek fisik, sosial, ekonomi dan lingkungan terhadap bencana yang umumnya dihadapi oleh r masyarakat.

Disamping itu dan tentang cara-cara dimana bahaya-bahaya dan kerentanan berubah dalam jangka waktu yang pendek dan panjang, diikuti oleh tindakan yang diambil atas dasar pengetahuan tersebut.

The starting point for reducing disaster risk and for promoting a culture of disaster resilience lies in the knowledge of the hazards and the physical, social, economic and environmental vulnerabilities to disasters that most societies face, and of the ways in which hazards and vulnerabilities are changing in the short and long term, followed by action taken on the basis of that knowledge.

Prioritas Aksi 3: Gunakan pengetahuan, inovasi dan pendidikan untuk membangun suatu budaya keselamatan dan ketahanan di semua tingkatan.

Priority Action 3: Use knowledge, innovation and education to build a culture of safety and resilience at all levels.

Bencana dapat dikurangi secara substansial (Disasters can be substantially reduced ) jika orang mendapat informasi yang baik dan termotivasi (if people are well informed and motivated) terhadap suatu budaya untuk pencegahan dan ketahanan bencana (a culture of disaster prevention and resilience), yang pada gilirannya memerlukan pengumpulan, kompilasi dan penyebaran pengetahuan dan informasi yang relevan (requires the collection, compilation and dissemination of relevant knowledge and information) tentang bahaya, kerentanan dan kapasitas (on hazards, vulnerabilities and capacities).

Disaster risks related to changing social, economic, environmental conditions and land use, and the impact of hazards associated with geological events, weather, water, climate variability and climate change, are addressed in sector development planning and programmes as well as in post-disaster situations.

Priority Action 4: Mengurangi faktor-faktor risiko yang mendasarinya.

Priority Action 4: Reduce the underlying risk factors.

Risiko bencana yang terkait dengan perubahan kondisi sosial, ekonomi, lingkungan dan penggunaan lahan, dan dampak bahaya-bahaya yang terkait dengan peristiwa geologis, cuaca, air, variabilitas iklim dan perubahan iklim, dibahas dalam perencanaan dan program pengembangan sektoral serta pada situasi-situasi pasca bencana.

Disaster risks related to changing social, economic, environmental conditions and land use, and the impact of hazards associated with geological events, weather, water, climate variability and climate change, are addressed in sector development planning and programmes as well as in post-disaster situations.

Priority Action 5: Memperkuat kesiapsiagaan bencana untuk merespon bencana yang efektif di semua level.

Priority Action 5: Strengthen disaster preparedness for effective response at all levels.

Pada saat terjadi bencana, dampak dan kerugian-kerugian yang ditimbulkan dapat sangat dikurangi, jika pihak-pihak berwenang, individu dan masyarakat di daerah rawan bahaya dipersiapkan dengan baik dan siap untuk bertindak dan juga dilengkapi dengan pengetahuan dan kapasitas untuk penanggulangan bencana yang efektif.

At times of disaster, impacts and losses can be substantially reduced if authorities, individuals and communities in hazard-prone areas are well prepared and ready to act and are equipped with the knowledge and capacities for effective disaster management.

LAMPIRAN:

Indonesia: National progress report on the implementation of the Hyogo Framework for Action (2013-2015)

The preparation of this National Progress Report has been undertaken within the framework of the 2013-15 HFA Monitoring and Progress Review process, facilitated by UNISDR and the ISDR partnership.

The progress report assesses current national strategic priorities with regard to the implementation of disaster risk reduction actions, and establishes baselines on levels of progress achieved with respect to the implementation of the HFA’s five priorities for action.

 

LAMPIRAN SLIDE SHOW:

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The Hyogo Framework for Action 2005-2015:Building the Resilience of Nations and Communities to Disasters

United Nations International Strategyfor Disaster Reduction (UN/ISDR)

http://www.unisdr.org

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The road to the Hyogo Framework for Action

  • 1989: IDNDR 1990-1999– promotion of disaster reduction, technical and scientific buy-in
  • 1994: Yokohama Strategy and Plan of Action– Mid-review IDNDR, first blueprint for disaster reduction policy guidance (social & community orientation)
  • 2000: International Strategy for Disaster Reduction (ISDR)- increased public commitment and linkage to sustainable development, enlarged networking and partnerships. Mechanisms: IATF/DR, ISDR secretariat, UN Trust Fund
  • 2002: Johannesburg Plan of Implementation- WSSDIncludes a new section on “An integrated, multi-hazard, inclusive approach to address vulnerability, risk assessment and disaster management…”
  • 2005: WCDR – Hyogo Framework for Action 2005-2015Building the Resilience of Nations and Communities to Disasters
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Hyogo Framework for Action 2005-2015:

  • Defines:
      • Strategic goals
      • Priorities for Action
      • Implementation and follow-up
  • Integrates disaster risk reduction into policies, plans and programmes of sustainable development and poverty reduction
  • Recognizes risk reduction as both a humanitarian and development issue – in the context of sustainable development
  • Focus on national implementation, with bi-lateral, multi-lateral, regional and international cooperation.
the strategic goals towards mainstreaming of disaster risk reduction into development
The strategic goals towards mainstreaming ofdisaster riskreduction into development

  • DRR integrated into sustainable development policies and programmes;
  • Strengthened institutional mechanisms to build capacities for resilience to hazards;
  • DRR as part of preparedness, relief and recovery
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SUMMARY of the Hyogo Framework for Action 2005-2015: Building the Resilience of Nations and Communities to Disasters (HFA)

 

TINJAUAN STUDI KASUS

Bahaya geologi di Indonesia: Ilmu Kebumian untuk Reduksi Risiko Bancana

Geohazards in Indonesia: Earth Science for Disaster Risk Reduction.

Geological Society, London, Special Publications, 441,

https://doi.org/10.1144/SP441.10 # 2017

From: Cummins, P. R. &Meilano, I. (eds)

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DOKUMEN INI ADALAH TAHAP AWAL UNTUK MENGKAJI SECARA MENDALAM BAIK ASPEK GEOHAZARD DI INDONESIA DAN KHUSUSUSNYA GEOHAZARD LUMPUR SIDOARJO, DIKONTRIBUSIKAN DR. ANDREAS.

Abstrak

Indonesia signifikan untuk risiko bahayaalam (geohazard): populasi penduduk padat dan terletak pada jalur tektonik paling aktif di dunia

Dengan populasi penduduk yang padat yang terletak di salah satu sabuk tektonik paling aktif di dunia (located in one of the most active tectonic belts in the world,), Indonesia adalah suatu daerah yang kumulatif signifikan untuk risiko bahaya alam (a hotspot for natural hazard risk).

Pencegahan meningkatnya korban fatal dari bencana alam telah berubah akhir-akhir ini, namun kemajuan ilmu kebumian untuk mengurangi korban bencana alam belum signifikan

Selama abad ke-20, Indonesia masih mempunyai keterbatasan sarana untuk mencegah meningkatnya korban fatal dari bencana alam, seiring meningkatnya pertumbuhan populasi yang eksplosif.

Situasi ini berubah cepat, dengan kemajuan politik dan ekonomi bermakna selama dua dekade terakhir ini, sehingga telah menyebabkan investasi besar dalam infrastruktur seismik dan geodetik.

Namun potensi kemajuan dalam ilmu kebumian untuk mengurangi korban bencana alam di Indonesia tidak pernah lebih besar.

Publikasi khusus ini merekam kemajuan terbaru dicapai oleh para ahli kebumian untuk pemahaman lebih baik tentang bahaya geologi di Indonesia

Publikasi Khusus ini mendokumentasikan beberapa kemajuan terbaru yang dibuat oleh para ilmuwan kebumian yang berkontribusi terhadap pemahaman yang lebih baik (that contribute towards a better understanding) tentang bahaya geologi di Indonesia (the geological hazards in Indonesia)

LAMPIRAN

 

Memahami pemicu semburan LUSI mud volcano dari tanda-tanda deformasi tanah

HERI ANDREAS 2017.

Kata Kunci: Diskusi dan Kesimpulan

  • Salah satu hipotesis asalmula semburan Lusi dipicu gempabumi Yogyakarta 2006 diikuti reaktifasi Patahan Watukosek – fluidasasi lumpur di reservoir
  • Hipotesis pendukung gempabumi Yogya telah difokuskan dan diperkuat oleh pemantul lapisan penutup sumber lumpur dengan geometri cekung atau berbentuk parabola
  • Tanda-tanda deformasi tanah yang diamati bahwa penurunan berbentuk kerucut dikendalikan oleh semburan lumpur dan tidak ada kaitan dengan reaktifasi patahan
  • Morfologi bunung Lusi dari hasil TLS tidak mendukung reaktifasi Patahan Watukosek
  • Berdasarkan data yang digunakan, hubungan Lusi dengan gempabumi Yogyakarta dimaknai paling lemah
  • Memperkokoh studi deformasi terdahulu berdasarkan GPS & InSAR bahwa Lusi mud volcano didominasi oleh amblesan
  • Tahun 2010 telah terjadi perlambatan kecepatan deformasi amblesan yang signifikan dengan pola peluruhan eksponensial, sinyal semburan dapat menjadi “dormant”

Diskusi dan Kesimpulan

  • Salah satu Hipotesis asalmula semburan Lusi adalah dipicu gempabumi Yogyakarta 2006 diikuti reaktifasi Patahan Watukosek – fluidasasi lumpur di reservoir

Studi-studi tentang semburan gunung lumpur LUSI (LUSI mud volcano) yang telah dipublikasikan sebelumnya, berhipotesis bahwa Lusi dipicu oleh reaktivasi patahan lokal karena gelombang seismik berasal dari gempabumi Yogyakarta 27 Mei 2006 (it was triggered by the reactivation of a local fault due to seismic waves from the Yogyakarta earthquake).

Mazzini dkk. (2007, 2009) menyimpulkan bahwa gempa Yogyakarta telah memicu semburan LUSI, karena efek hidrologi diinduksi gempa yang selanjutnya mengaktifkan kembali patahan di daerah LUSI.

  • Hipotesis gempabumi Yogya telah difokuskan dan diperkuat oleh pemantul dengan geometri cekung atau berbentuk parabola dari lapisan penutup sumber lumpur

Sementara itu Lupi dkk. (2013) mengusulkan bahwa lapisan batuan dengan geometri cekung yang menutupi reservoir sumber lumpur, dapat memfokuskan dan memperkuat gelombang gempa yang masuk dari gempabumi Yogyakarta 26 Mei 2006. Selanjutnya telah mengaktifkan kembali patahan dan memicu semburan lumpur LUSI.

  • Indikasi deformasi tanah menunjukkan penurunan berbentuk kerucut dikendalikan oleh semburan lumpur, tidak ada kaitan dengan reaktifasi patahan

Namun demikian, tanda-tanda deformasi tanah setelah semburan LUSI (the ground deformation signature following the LUSI eruption) adalah penurunan yang berbentuk kerucut (is  cone-shaped subsidence).

Merupakan suatu fenomena yang diharapkan jika material bawah permukaan diekstrusi ke permukaan (if subsurface material was extruded onto the surface) misalnya dalam semburan gunung lumpur.

Adalah sulit untuk dapat menyimpulkan bahwa pola deformasi yang diamati tersebut, terkait dengan reaktifasi patahan (observed deformation pattern is associated with fault reactivation).

  • Morfologi gunung Lusi dari hasil (Terrestrial Laser Scanner) TLS tidak mendukung reaktivasi Patahan Watukosek

Morfologi dari gunung lumpur LUSI yang telah ditentukan menggunakan survei pemindaian laser terestrial (TLS) dengan akurasi tinggi (a high-accuracy terrestrial laser scanning survey), ternyata tidak mendukung fenomena reaktifasi dari Patahan Watukosek (does not support reactivation of the Watukosek Fault).

  • Berdasarkan data yang digunakan, hubungan Lusi dengan gempabumi Yogyakarta dimaknai paling lemah

Meskipun sulit untuk menyingkirkan argumen fokus seismik dari Lupi et al. (2013), namun berdasarkan data lapangan yang dihimpun dari studi ini, bahwa hubungan gunung lumpur LUSI dengan gempa Yogyakarta tampaknya lemah (the connection of the LUSI mud volcano with the Yogyakarta earthquake seems tenuous at best).

Sejalan dengan kesimpulan ini, Davies dkk. (2007) membandingkan antara parameter jarak dan kekuatan gempa, dengan historis hubungan antara jarak dan kekuatan gempa bumi yang telah menyebabkan likuifaksi sedimen, selanjutnya memicu semburan gunung lumpur atau menyebabkan respons hidrologi lainnya.

Dengan perbandingan tersebut, selanjutnya disimpulkan bahwa Lusi dipicu gempabumi Yogyakarta aalah tidak mungkin (by this comparison, an earthquake trigger is unlikely).

  • Memperkokoh studi terdahulu berdasarkan GPS & InSAR bahwa deformasi Lusi mud volcano didominasi oleh amblesan

Pertimbangan rinci tentang tanda-tanda deformasi tanah pada awal semburan (2006–2007), berdasarkan survei GPS dan pengukuran InSAR oleh Abidin et al. (2008) dan pengukuran InSAR oleh Fukushima dkk. (2009) semuanya dengan jelas telah menerangkan bagaimana deformasi tanah terjadi di sekitar gunung lumpur LUSI.

Tingkat deformasi vertikal dan horizontal hingga sekitar 4 dan 1 cm/hari, masing-masing diamati pada periode waktu tersebut.

Abidin dkk. (2008) dan Davies dkk. (2010) juga membuat proyeksi total subsidence sebesar 100 m selama dekade berikutnya. Sinyal deformasi tanah besar seperti itu akan menjadi luar biasa.

  • Tahun 2010 telah terjadi perlambatan kecepatan amblesan yang signifikan dengan pola peluruhan eksponensial, merupakan sinyal bahwa semburan dapat menjadi dormant

Namun yang terjadi lebih dari empat tahun setelah semburan Lusi (2010), dimana deformasi tanah yang diamati menunjukkan pola peluruhan eksponensial (the observed ground deformation is showing an exponential decay pattern), dengan laju melambat menjadi hanya beberapa cm/tahun selama empat tahun setelah semburan (with rates having slowed to only several cm a four years after the eruption).

Setelah melalui tahapan intensitas deformasi besar yang berlangsung pasca  awal semburan, sehingga indikasi penurunan kecepatan amblesan dengan peluruhan eksponensial dari hasil studi ini mungkin dapat menunjukkan akhir dari semburan gunung lumpur LUSI (these results might be indicating the end of the LUSI mud volcano eruption).

Sebagai implikasi bahwa terjadinya pengurangan signifikan dari kecepatan deformasi amblesan dapat mengindikasikan (A decrease in the deformation rate may indicate), bahwa kekuatan yang mendorong semburan Lusi telah dihabiskan (the forces driving the eruption have been spent). Sehingga semburan lumpur akhirnya akan segera berakhir (so that the mud eruption is finally coming to an end).

FGD 12 Nov 2015 Geoheritage Lusi layak sebagai Kandidat GeoPark

Juni 3, 2018

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Sejarah Penanggulangan LUSI 2006-2017 12 November 2015

Pertemuan Focus Group Discussion Di Ruang Sunarso, BPLS.

Dipimpin oleh Dr. Junus, Ketua Tim Satgas Geopark  Indonesia,.

Presentasi “Pernyataan Tujuan Geopark Lusi ” Oleh  Dr. Hardi Prasetyo

Potensi Fenomena Geoheritage untuk pengusulan GeoPark Lusi”.

Kesimpulan Lusi layak diusulkan sebagai Geopark. ditindaklanjuti dengan Pembentukan Tim Percepatan Pembangunan Geopark Lusi

Dikoordinasikan oleh Prof. Hardi Prasetyo

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12 November 2015,  Pertemuan Focus Group Discussion di Ruang Sunarso, BPLS, Surabaya.

Dipimpin Dr. Ir. Yunus Kusumahbrata

 Ketua Tim Satgas Geopark Indonesia.

Kesimpulan  Usulan Lusi Geoherigate  sebagai GeoPark Layak dan Lanjut Pembentukan Tim Percepatan Pembangunan Geopark Lusi         dikoordinasikan oleh Dr. Hardi Prasetyo.

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BAGIAN I: KONSEP GEOPARK DAN PERKEMBANGANNYA DI INDONESIA DAN DUNIA

GEOPARK : DESTINASI WISATA UNGGULAN NASIONAL

Dr. Yunus Kusumahbrata, Ketua Tim Task Force Pengembangan Geopark Indonesia, KEMENTERIAN ESDM

FILE AKAN DILANJUTKAN:

 

 

Snyder dan Prasetyo: Penampang seismik dalam Banda-Australa

Juni 3, 2018

Seri Tektonik dan Geologi  NEGARA MARITIM INDONESIA

Snyder dan Prasetyo

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Postur deformasi kerak memotong zona tumbukan kotinen-busur di Busur Banda diamati dari penampang seismik dalam

Style of crustal deformation across the Banda Arc continent-arc collision zone as observed on deep seismic reflection profiles

D.B. Snyder, H. Prasetyo, D. J. Blundell, C. J. Pigram, A. Richardson, S.Tjokosaproetro, J. Milsom & A. J. Barber

 Sumber: http://www.bpls.go.id/bplsdownload/library/humanitus/deepseismik-1.pdf

                      Dikontribusikan oleh: Dr. Hardi Prasetyo Sebagai bagian                        “Science Manager”  Penanggulangan Bencana LUSI 2007-2017

DAFTAR ISI:

Abstrak

Abstract Orie

Kesimpulan

Conclusion

Lampiran Gambar

INTRODUCTION

     Structures on Timor

     Inner Banda Arc

PREVIOUS GEOPHYSICAL STUDIES

ACQUISITION & PROCESSING OF NEW SEISMIC DATA

     Migrations

     Interval velocity analysis

STRUCTURES FROM SEISMIC REFLECTOR GEOMETRIES

     The Timor Sea and northern margin of the Australian continental shelf

     The accretionary complex near Timor

     The Banda volcanic arc

A LITHOSPHERIC PERSPECTIVE

     Elastic flexure of the Australian lithosphere

     Possible uplift mechanisms for the Inner and Outer Arcs

Figure Captions

REFERENCES

Abstrak

Penampang seismik refleksi dalam yang baru memotong Busur Banda (New deep seismic reflection profiles across the Banda Arc) Indonesia telah menunjukkan reflektor-reflektor 50 km bagian  paling atas  litosfer (revealed reflectors in the uppermost 50 km of the lithosphere).

Kombinasi geometri struktur baru (combination of new structural geometries) yang disimpulkan dari pemantul dengan lokasi hiposenter gempa bumi yang telah ada dan mekanisme fokus (inferred from the reflectors with existing earthquake hypocenter locations and focal mechanisms) menghasilkan suatu analisis deformasi yang lebih lengkap mencakup 10 Juta tahun terakhir.

Juga menyediakan suatu wawasan tentang bagaimana strain dipartisi memotong jalur orogenik (provides insights into how strain is partitioned across an orogenic belt), dimana suatu busur vulkanik dan benua saling berkonvergensi (in which volcanic arcs and continents converge).

Suatu zona Wadati-Benioff yang terdefinisi dengan jelas (a clearly defined Wadati-Benioff zone) dan deformasi terbaru sedimen di paparan yang diamati pada profil seismik dangkal (recent deformation of shelf sediments observed on shallow seismic profiles), menunjukkan bahwa konvergensi yang signifikan  terjadi di Palung Timor (substantial convergence occurred at the Timor Trough).

Beberapa mekanisme-mekanisme pusat gempa (a few focal mechanisms), gawir di dasar laut (seafloor escarpments), dan survei terbaru (CPS) menunjukkan bahwa konvergensi dengan kecepatan ~ 7 cm/tahun saat ini terjadi di tepian utara (that convergence at ~7 cm a-1 currently occurs at the northern margin) dari busur vulkanik yang sekarang tidak aktif, yaitu zona Sesarnaik Wetar (the now inactive volcanic arc, the Wetar Thrust zone).

Reflektor yang ditafsirkan sebagai sesar naik dan lipatan (Reflectors interpreted as thrust faults and folds) yang terjadi di seluruh kerak dan di dalam mantel paling atas (occur throughout the crust and within the uppermost mantle) di bawah keseluruhan dari Busur Banda antara Palung Timor dan Sesarnaik Wetar (beneath the entire Banda Arc between the Timor Trough and Wetar Thrust), pada area penampang yang baru dan menunjukkan bahwa pemendekan horizontal di kerak terjadi dalam suatu jalur lebar 200 km (indicate that horizontal shortening in the crust occurs within a belt 200-km wide).

Reflektor batuandasar dengan  arah gerak terbalik di bawah ujung kompleks prima akrasi (basement reflectors with reverse-sense offsets beneath the toe of the accretionary complex). Telah menyiratkan bahwa keseluruhan kerak mengalami deformasi, bukan hanya pada paket sedimen (the whole crust is deforming, not only sediments).

Bukti penyesaran naik pada tepian utara  dari busur vulkanik (Evidence of thrusting at the northern margin of the volcanic arc) dicocokkan dengan reflektor-reflektor yang miring menjauhi dari kedua tepian dari cekungan busur depan (reflectors dipping away from both margins of the forearc basin).

Ketebalan kerak yang disimpulkan dari kecepatan, reflektor, dan anomali gravitasi (crustal thicknesses inferred from velocities, reflectors, and gravity anomalies) konsisten dengan penggabungan tepian paparan kontinen yang menipis dengan litosfer samudera (are consistent with the merging of a thinned continental shelf margin with oceanic lithosphere). Untuk membentuk suatu jalur orogenik saat ini dengan topografi relief 3-4 km di daerah Timor timur (to form an orogenic belt with at present 3-4 km of topographic relief in the area of eastern Timor).

Geometri ini juga konsisten dengan yang diprediksi oleh model numerik dari jalur orogenik vergenik ganda (of doubly vergent orogenic belts).

Deformasi mantel dapat disimpulkan hanya dari pusat  gempa (Mantle deformation can be inferred from earthquake hypocenters only); ekspresi yang jelas dari zona Wadati-Benioff pada kedalaman 70 km (an apparent contortion of the Wadati-Benioff zone at 70 km depths) mendukung saran sebelumnya bahwa subduksi saat ini berbalik arah (that subduction is presently reversing).

Abstract Orie

 New deep seismic reflection profiles across the Banda Arc of Indonesia have revealed reflectors in the uppermost 50 km of the lithosphere.

The combination of new structural geometries inferred from the reflectors with existing earthquake hypocenter locations and focal mechanisms yields a more complete analysis of deformation during the past 10 Ma and provides insights into how strain is partitioned across an orogenic belt in which volcanic arcs and continents converge.

A clearly defined Wadati-Benioff zone and recent deformation of shelf sediments observed on shallow seismic profiles indicated substantial convergence occurred at the Timor Trough.

A few focal mechanisms, seafloor escarpments and very recent surveying (CPS) indicate that convergence at ~7 cm a-1 currently occurs at the northern margin of the now inactive volcanic arc, the Wetar Thrust zone.

Reflectors interpreted as thrust faults and folds occur throughout the crust and within the uppermost mantle beneath the entire Banda Arc between the Timor Trough and Wetar Thrust in the area of the new profiles and indicate that horizontal shortening in the crust occurs within a belt 200-km wide.

Basement reflectors with reverse-sense offsets beneath the toe of the accretionary complex imply that the whole crust is deforming, not only sediments. Evidence of thrusting at the northern margin of the volcanic arc is matched by that of reflectors dipping away from both margins of the forearc basin.

Crustal thicknesses inferred from velocities, reflectors, and gravity anomalies are consistent with the merging of a thinned continental shelf margin with oceanic lithosphere to form an orogenic belt with at present 3-4 km of topographic relief in the area of eastern Timor.

These geometries are also consistent with those predicted by numerical models of doubly vergent orogenic belts.

Mantle deformation can be inferred from earthquake hypocenters only; an apparent contortion of the Wadati-Benioff zone at 70 km depths supports previous suggestions that subduction is presently reversing.

 Kesimpulan

 Sesar-sesar naik melibatkan batuan dasar (Basement thrusts) yang disimpulkan dari perlipatan sedimen di atasnya, tidak sesuai dengan model standar prisma akrasi  (is incongruous with standard accretionary wedge models).

Disamping itu menunjukkan suatu pemendekan horizontal terjadi lebih dalam (horizontal shortening occurred deeper) di dalam kerak zona konvergen busur Banda (within the crust of the Banda arc convergent zone).

Pemantul seismik yang miring ke dalam dari kedua tepian busur vulkanik yang tidak aktif (dip inward from both margins of the inactive volcanic arc).

Geseran, indikator dari pergerakan (sense of offset indicators), dan pengangkatan (uplift) semua telah mengindikasikan pergerakan sesarnaik di sepanjang reflektor (dip inward from both margins of the inactive volcanic arc)  dan pemendekan horizontal di sepanjang busur vulkanik (dip inward from both margins of the inactive volcanic arc).

Ketika dilihat dalam hal pemodelan numerik terbaru dari orogen-orogen, sabuk orogenik ganda ini  (numerical modeling of orogens, these dual doubly vergent orogenic belts) menunjukkan adanya pergerakan ke utara dari zona subduksi mantel (suggest a recent northward transfer of the mantle subduction zone).

Pergeseran yang terus berlangsung ini menciptakan zona deformasi yang luas (ongoing shift creates a broad zone of deformation) di atas dari kerak kontinen kerak dan kerak samudera yang menebal (the overlying continental and thickened oceanic crust).

CONCLUSIONS

Available ages of dated igneous rocks indicate the formation of an island arc above a subducted slab 1~3 Ma, followed by cessation of igneous activity and initiation of uplift of the accretionary Outer Banda arc at 3 Ma.

Reflector geometries observed within the accretionary complex are consistent with thrust imbricate models based upon field mapping on Timor and similar accretionary wedges worldwide.

Basement thrusts inferred from folding of overlying sediments is incongruous with standard accretionary wedge models and indicates horizontal shortening occurred deeper within the crust of the Banda arc convergent zone.

Reflectors dip inward from both margins of the inactive volcanic arc. Scarps, sense of offset indicators, and uplift all indicate thrust-sense displacements along these reflectors and horizontal shortening across the volcanic arc.

When viewed in terms of recent numerical modeling of orogens, these dual doubly vergent orogenic belts suggest a recent northward transfer of the mantle subduction zone. This presumed ongoing shift creates a broad zone of deformation in the overlying continental and thickened oceanic crust.

Lampiran Gambar

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INTRODUCTION  

The present day Banda Arc results from the complex convergence of the northern margin of the Australian continental lithosphere with terranes of both oceanic and continental affinity to its north.

It has become an often cited example of the early stages of arc-continent convergence and subsequent mountain building, yet remains incompletely understood and its structures hotly debated [e.g. Karig et al., 1987; Hamilton, 1988] The ~2000 km long arc

includes the major islands of Timor and Seram in the Outer Banda Arc and the numerous active volcanoes of the Inner Banda Arc (Fig. IA) [Hamilton, 1979].

The part of the Banda arc east of, and including, Timor is the only active major convergence zone where a continent is currently subducting beneath oceanic lithosphere.

Within 500 km east of Timor, the strike of the subduction zone turns to the northeast and produces three dimensional strains on the subducted continental and overriding oceanic lithospheres [Cardwell & Isacks, 1978].

To the west, oceanic lithosphere subducts beneath oceanic crust south of the arc islands from Flores to Bali (Fig. lA), and beneath the continental lithosphere of Java and Sumatra further to the west. The short segment of the Banda Arc just east of Timor, where continental lithosphere subducts nearly normal to the trace of the plate boundary [Cloetingh & Wortel, 1986; De Mets et al., 1990], was chosen for exploration by deep seismic reflection techniques in order to detail styles of continental deformation and Many previous studies of the Outer Banda Arc [e.g. Hamilton, 1979, 1988; Silver et al., 1983; Karig et al., 1987] viewed its tectonic development in terms of an accretionary prism resulting from the northward subduction of Australian lithosphere beneath the volcanic Inner Banda Arc (Fig. 2). Other studies indicate that the New Guinea Orogen was initiated in the middle-late Oligocene as the northern edge of the Australian craton collided with several arc complexes, oceanic plateaus and micro-continents [Pigram et al., 1989]. Veevers [1984] was the first to link the various tectonic elements of Australia’s northern margin into a unified development history in which a foreland basin and frontal thrust coupled to an orogen could be traced along its entire 5000 km length.

Later studies interpreted the Timor-Tanimbar-Aru troughs as young foreland basins (proximal foredeeps) caused by flexural loading of the Australian continental margin by  emplacement of a thrust mass [Audley-Charles, 1986].

It is now generally accepted that strain within continental deformation zones is distributed over belts hundreds of kilometers wide [e.g. England & Jackson, 1989].

In the Banda Arc three types of geophysical data can each provide limited information about strain distribution during the past 2.2 Ma period that active arc-continent collision has occurred there.

Near-surface deformations based on GPS measurements provide cumulative strain measurements over the past few years, earthquake hypocentre distributions and focal mechanisms provide estimates of instantaneous strain for the entire lithosphere over several decades, and seismic reflectors inferred to represent faults and shear zones show the geometries of strain accumulated over several Ma.

The near-surface deformation and earthquake data indicate that crustal deformation is currently concentrated in the volcanic arc [McCaffrey, 1988; Genrich et al., 1993], whereas shallow seismic data shows disrupted Cenozoic sediments both in the back arc region [Silver et al., 1983] and in the Timor Trough [Karig et al., 1987].

The new deep seismic reflection profiles show reflections indicating basement faults and shear zones throughout the crust beneath the Timor Trough and both north and south-dipping reflectors within the oceanic lithosphere beneath the volcanic arc.

Previous uplift studies [DeSmet et al., 1990] and block tilting indicated by dipping and locally disrupted thin sediments in the forearc basin observed on the new seismic lines indicate that the entire arc has deformed over the past 2.2 Ma, but that strain was concentrated near the Timor Trough, and most recently, north of the volcanic arc.

The addition of deep seismic reflection profiles to existing, lower resolution geophysical data sets defines more clearly the details of structures absorbing the continental collision, to resolve whether viewing the zone as an accretionary prism or foreland foldand-thrust belt provides greater insight into the kinematics and possibly the dynamicsof continental collision. Results indicate that Australian lithosphere is underthrust only tens of kilometers beneath the Outer Banda Arc before becoming strongly deformed by reverse or thrust faults, and clear evidence of complete subduction reversal is not observed. No strong, continuous plate exists to provide enough mechanical integrity for elastic flexure, and the Timor Trough cannot be viewed simply as either a foreland basin or a subduction zone.

GEOLOGICAL SETTING

Outer Banda Arc

 The northern margin of the Australian continent is presently colliding with the volcanic islands of the Banda Arc which stand on oceanic crust of the Banda Sea (Fig 1A). Since at least 38 Ma ago oceanic lithosphere or highly attenuated continental lithosphere of

the Australian plate subducted northwards beneath the Banda Sea at about 75 mm a~ with local or periodic incorporation of small terrains, continental crustal blocks or oceanic plateau, in the accretionary complex [Hamilton, 1979; Harris, 1991, and references therein]. For example, emplacement of ophiolites on Timor (Mutis Fm. Of Table 1) and the smaller islands to the east was dated at 38 Ma by the intense inverted metamorphism of sediments directly beneath the deformational contact with the ophiolite [Berry & Grady, 1981; Sopaheluwakan, 1990].

About 2.2 Ma ago the full-thickness continental crust and lithosphere of the Australian margin apparently arrived at the trench near eastern Timor [De Smet et al., 1990].

Continuous subduction ceased and episodic uplift of the arc began. On Timor, two episodes of rapid uplift, 5 mm a-1 from 2.2-2.0 Ma and 7,5-10 mm a-1 during the last 0.2 Ma produced uplifts of 150~2500 m [De Smet et al., 1990]. The highest parts of the forearc ridge, the Outer Banda Arc, have risen above sea level to form a chain of smaller islands in the segment of the arc between Timor and Seram. Structures (S2) in northeastern Timor may indicate an earlier shortening event in the Late Miocene at 8-16 Ma, when outlying continental fragments were emplaced onto the Australian shelf margin (Table 1) [Berry & Grady, 1981].

The margin contains Paleozoic basins, such as the Arafura Basin, and Mesozoic rift basins, such as the Vulcan Sub-basin, Malita-Calder Graben, and Money Shoal Graben, which began to develop along the Gondwanaland/Tethyan margin possibly in the Late Triassic (Table 1) [Schluter & Fritsch, 1985]. By the end Jurassic the northern margin of the Australian craton faced a seaway which linked the proto-Pacific and proto-Indian oceans [Pigram & Panggabean, 1984) and contained regions where lithosphere had thinned to half its original thickness [O’Brien et al., 1993].

Islands within the orogen, such as Timor, were predicted to contain components of the Australian craton, the earlier accretionary prism derived from subduction of the Tethys ocean, and deformed foreland sediments [Audley-Charles, 1986]. Pre-Pliocene shelf deposits in the Timor Trough consist of a shallowing sequence but are covered by progressively deepening sediments in the Pliocene and Quaternary [Veevers et al., 1978; Johnson & Bowin, 1981; Karig et al., 1987].

This abrupt deepening in the Pliocene coincides with the rapid uplift of Timor from 2.2-2.0 Ma, and suggests a regional adjustment in the arc-continent convergence [De Smet et al., 1990].

Structures on Timor

 Although relatively short and well studied, the geological history of Timor has been notably difficult for geologists to agree unanimously (Fig. 2), perhaps because the stratigraphy was partly inverted with the oldest rocks lying at the top of upright sections and many relationships were obscured by mud diapirism [Barber et al., 1986].

The oldest known rocks on Timor are the intimately related Lolotoi ophiolites and underlying Mutis Complex metasediments containing an inverted metamorphic gradient. By tentatively correlating the Mutis/Lolotoi Complex across Timor and by assuming that the metamorphosed underlying sediments are mostly Mesozoic Australian shelf sediments [including the Aileu Fm. of Berry & Grady, 1981], these rock relationships can be interpreted as thin oceanic crust thrust onto the distal edge of a thin and attenuated Australian continental shelf.

Radiometric dates indicate peak metamorphism at 118+38 Ma (mid Cretaceous) and a prograde metamorphic event in the Late Focene at ~38 Ma when the rocks are presumed to have been emplaced onto the Australian shelf margin [Audley-Charles, 1968; Sopaheluwakan, 1990; Chariton et al., 1991]. Some of the underlying pre-Cretaceous rocks have close structural, statigraphic, and paleomagnetic links to mainland Australia [Berry & Grady, 1981; Johnston & Bowin, 1981], and probably represent the greatly thinned or partially rifted, northernmost edge of the Australian craton.

These rocks experienced a phase of tight folding at 11-8 Ma associated with gradual cooling [Berry & McDougall, 1986], and today occur at high structural levels on Timor, lying on top of a partly underthrust accretionary complex of deep oceanic sediments Cretaceous to Early Pliocene in age (Table 1) [Charleton et al., 1991; Harris, 1991].

These underthrust sediments include the Kolbano unit exposed along the south coast of Timor that contains a series of northward dipping thrusts, recumbent folds and imbricate thrust sheets that comprise most of the southern third of Timor [Charlton et al., 1991). Subduction of oceanic crust and slow accretion presumably continued in deep water from 8-3 Ma while a layer of molasse (calcilutite) sediments, the Viqueque Group, were deposited in elongate basins on top of the Kolbano rocks and a distinctive pelagic limestone, the Batu Puti Formation, mantled the entire Timor block. The Viqueque Group’s depositional environment shallowed significantly in the mid-Pliocene at 2.2 Ma with the inferred arrival of the full-thickness Australian continental margin at the subduction zone trench [De Smet et al., 1990].

In the last 2.2 Ma, thick Mesozoic and Eocene sediments from the Bonaparte and Westralian Rift Basins on the Australian shelf formed relatively intact large thrust sheets that underplated both the Kolbano and parautochthonous blocks, uplifting them and locally rotating them down to the north [Charlton et al., 1991]. Thrusting continued until the Late Pliocene when southern Timor finally emerged from the sea. Some workers claim that by 0.2 Ma Timor was strongly attached to the Australian margin and the trench became a thrust deformation front, absorbing only a small part of the total convergence [Johnston & Bowin, 1981; De Smet et al., 1990].

Between 0.2 Ma and the present, north-northwest convergence continued at 7W75 mm a-1 [Cloetingh & Wortel, 1986; DeMets et al., 1990] and Timor continued to rise at 7.5- 10.0 mm a-1 [De Smet etal., 1990] as shelf sediments formed underthrust wedges and the Australian crust thickened. In this interpretation, the former subduction complex (from trench to volcanic arc) shortened horizontally by 200 km during the past 40 Ma [Johnson & Bowin, 1981], and the crust beneath Timor thickened to as much as 60 km [Mccaffrey et al., 1985].

Inner Banda Arc

The volcanoes of the Banda Arc between Flores and Damar have been inactive for the past 3 Ma [Abbott & Chamalaun, 1981). Damar volcano and the arc volcanoes to the east-northeast of the survey area remain active. Gunung Api is an unusual in that its edifice was constructed on the back-arc oceanic crust of the Banda Sea approximately 400 km above the Wadati-Benioff zone. It has been active in historic times, with Portuguese sailors reporting eruptions in 1800.

Age dating and geochemical analysis of a combined suite of diorite dykes and pyroclastic extrusives along the inactive part of the arc at Alor and Wetar (Fig. 1) suggest that igneous activity started >12 Ma ago and continued above a subducting slab until 3 Ma [Abbott & Chamalaun, 1981). Three volcanic centers on the nearby island of Atauro were dated at 3.10, 3.3, and 3.45 Ma, indicating the rapidity with which the

centers formed. Pillow lavas of the Oecusse volcanics on the north coast -of Timor have tholeutic compositions and ages of 6 Ma. These rocks are interpreted to have formed within the volcanic arc and were thrust onto Timor from the north as ophiolites [Abbott & Chamalaun, 1981].

Taken together these dates indicate the formation of an island arc

above a subducted slab 1~3 Ma ago. Arc volcanism ceased in the Timor sector at 3 Ma and studies of coral reef terraces indicate that the arc islands of Wetar and Alor have been tilted and uplifted by 1 km since that time [Chappell & Veeh, 1978; Katili & Soetadi, 1971].

The fate of the subducted slab [McBride & Karig, 1987) has recently been clarified by isotope studies within this inactive part of the volcanic arc [Hilton et al., 1993). Between Flores and Damar, trends in 3He-4He ratios in erupted lavas indicate that radiogenic He comes from continental crust that has been subducted to 150 km depths where it has melted. Comparison of He and Sr isotope ratios indicates that the source is crystalline crust and not recycled terrigenous sediments [Hilton et al., 1993]. In the Flores region, the transition in He isotope ratios from those associated with radiogenic He from continental crust (~2) to those of primordial He usually associated with oceanic (MORB) rocks (>5) occurs along a northeast-trending zone that coincides with surface strike-slip faults [Breen et al., 1989], crustal-scale fault planes defined by microearthquakes [Mccaffrey et al., 1985], and the projected northwest margin of the Australian continent (Fig. IA). These results indicate that continental crust subducted to at least 100-150 km depths in the eastern Timor segment of the Banda Arc.

PREVIOUS GEOPHYSICAL STUDIES

The Banda Arc region has received sporadic geophysical interest over the last few decades. Petroleum exploration occurred in 1967-1974 when a number of seismic reflection surveys were carried out.

The Australian shelf remains an active exploration target today [e.g. O’Brien et al. 1993], and regional [e.g. Hamilton, 1979) and more local studies [e.g. Harris, 1991] have drawn upon these survey results. The volcanic arc has been surveyed in recent years by side-scan sonar, shallow seismic reflection techniques, gravity, and some sample dredging [Silver et al., 1983; Karig et al., 1987; Jongsma et al.,; Masson et al., 1991].

Combined, these surveys have provided a wealth of information about structures in the uppermost 5 km of the crust; those structures in parts of the trench and volcanic arc near Timor have particularly fueled debate concerning the relative importance of current tectonic activity at the sites of the Timor Trough and Wetar Thrust.

Crustal scale structures were investigated using short-term seismic networks to complement global teleseismic studies [McCaffrey et al., 1985; Mccaffrey, 1988], refraction profiling in the trench and backarc [Bowin et al., 1980], and regional gravity surveys [Chamalaun et al., 1976; Milsom & Audley-Charles, 1985; McBride & Karig, 1987]. The gravity field of this part of the arc remains sparsely sampled, but both the Darwin and Snellius II cruises collected densely spaced gravity measurements, Darwin along the DAMAR seismic profile [Masson et al., 1991], Snellius II along the TIMOR profile [Jongsma et al., 1989].

Mantle structure is known from the very active Wadati-Benioff zone beneath the Banda Arc where earthquakes have been reliably located down to 11O.2 km depths and observed down to 700 km [Cardwell & Isacks, 1978; Mccaffrey, 1988]. The Wadati- Benioff zone is clearly observed in the vicinity of Sumba Island (Fig. lA), but not beneath Timor [Cardwell & Isacks, 1978]. The shallow depths of earthquakes within the oceanic lithosphere of the backarc, the Banda Sea, led McCaffrey [1988] to conclude that

the Wetar Thrust zone presently has a high seismic slip rate, but does not necessarily represent subduction reversal. Seismic moments indicate that the rate of north-south shortening across the entire arc near Timor is 20% that predicted by plate motion models.

Earthquake hypocentre locations from a local seismic network operated for 3 months in 1976 using stations on the islands of Damar, Moa, & Banda (Fig. IA) [I. Reid, 1993, unpublished data] provided estimated +10 km accuracies and defined the shallowest

parts of the Wadati-Benioff zone in the immediate vicinity of the deep seismic profiles (Fig. 3). Small (3<mb<4) earthquakes confirm the results of the teleseismic studies:

below 150 km the Wadati-Benioff zone dips northward at 450 and projects to the surface at the Timor Trough. Earthquakes between 7~14O km depths form a nearly vertical trend that suggests a non-planar shape for the subducted slab or flexing of the subducted uppermost mantle of Australia if the earthquakes can be assumed to occur in subducted oceanic crust (Fig. 3) [Kirby et al., 1993].

Shallow reflection profiles from western Timor indicate deformation of Australian shelf sediments into typical accretionary prism structures in the vicinity of the Timor Trough, similar profiles northwest of Timor detect little if any deformation of the Savu Basin sediments [Karig et al., 1987]. These observations suggest that significant amounts of plate convergence are absorbed at the Timor Trough or, possibly, if the entire arc acts as a rigid block, at the Wetar Thrust Very recent (1991-93) Global Positioning System (GPS) surveys within the Banda Arc indicate that the islands of Wetar, Timor, and Flores [Genrich et al., 1993] are moving northward with the same relative velocity vector as the Australian continental plate vector determined from global plate motion solutions (Pig. IA) [DeMets et al., 1990]. Teleseismically determined earthquake hypocentres within the lithosphere of this region appear concentrated near the top of the Wadati-Benioff zone

with a sparse background activity more uniformly distributed (Fig. 3). The few large earthquakes recorded within the eastern Timor area since 1962 and that have precise hypocentre locations and well-determined focal mechanisms indicate predominantly thrust mechanisms within the upper 40 km of inferred oceanic lithosphere beneath the Banda Sea and Inner Banda Arc [McCaffrey, 1988].

The new deep reflection lines provided new constraints in that reflectors can provide both high spatial resolution of deformation structures (geometries) at depth and integration of cumulative deformation over periods of time.

For example, a recently ruptured fault within basaltic crust may not be reflective unless it is also a conduit for magma or hydrothermal fluids, whereas a shear zone active for 3 Ma would probably some reflections due to mechanical and chemical alterations to rock material within the shear zone or juxtaposition of different rock types if displacements are great.

Here these new constraints are added toward a more complete interpretation and understanding of deformation in the Banda Arc.

ACQUISITION & PROCESSING OF NEW SEISMIC DATA

In February, 1992, the British Institutions Reflection Profiling Syndicate (BIRPS) and the Indonesian Marine Geological Institute (MGI) jointly conducted a deep seismic reflection survey acquiring two long profiles east of Timor in order to better understand the geologic history of Timor and to investigate the deep structure of the collision zone.

The survey entered Australian waters to join up with a NW Shelf survey acquired by Australian Geological Survey Organisation (ASGO) in March, 1993 (Figs. 1A & 4). Two nearly parallel lines were chosen in order to increase confidence in the regional consistency and significance of reflections. Both were located to cross the deformation zone close to Timor and the geologically contiguous islands to the east, in order to correlate the seismic sections with surface geology derived from field mapping (Fig. 1).

The TIMOR line was recorded to 18 5 TWTT and thus imaged reflections to 45 km depths. The eastern, DAMAR line was located near the active volcano Damar where deep earthquakes are frequent; it was therefore recorded to 37 5 TWTT in order to compare reflectors at 130 km depths with earthquake hypocenter locations.

In February, 1992, the British Institutions Reflection Profiling Syndicate (BIRPS) and the Indonesian Marine Geological Institute (MGI) jointly conducted a deep seismic reflection survey acquiring two long profiles east of Timor in order to better understand the geologic history of Timor and to investigate the deep structure of the collision zone.

The survey entered Australian waters to join up with a NW Shelf survey acquired by Australian Geological Survey Organisation (ASGO) in March, 1993 (Figs. 1A & 4). Two  nearly parallel lines were chosen in order to increase confidence in the regional consistency and significance of reflections. Both were located to cross the deformation zone close to Timor and the geologically contiguous islands to the east, in order to correlate the seismic sections with surface geology derived from field mapping (Fig. 1).

The TIMOR line was recorded to 18 5 TWTT and thus imaged reflections to 45 km depths. The eastern, DAMAR line was located near the active volcano Damar where deep earthquakes are frequent; it was therefore recorded to 37 5 TWTT in order to compare reflectors at 130 km depths with earthquake hypocenter locations.

More than 750 km of seismic profiles were acquired by M/V GECO Kappa using a 70 m-wide air gun array of 7324 in3 capacity designed to produce 97 bar m peak-to-peak pressure at 3-62.5 Hz frequencies [Hobbs and Snyder, 1993]. Shots were spaced at 50 or 100 m intervals and recorded at 4 ms sampling rate from a 96-channel hydrophone streamer of 4.6 km length. Water depth varies between 100 m and 4000 m and produces strong seabed multiples which partly obscure deeper primary reflections. Possible wrap-around multiples in areas of flat, deep (4-5 km depth) seafloor [McBride et al., 1994] were not a problem because selective availability on the GPS satellites used for navigation caused shot intervals to vary from 22 to 54 5 in a sinusoidal pattern that effectively randomized the shots.

In areas of shallow or slowly varying water depths, the 4600 m hydrophone offsets enabled the use of NMO-related differentiation between primary and shallow multiple reflections [Hardy and Hobbs, 1991, and references therein]; the combined use of UKfilters and inner trace mutes was effective in some but not all parts of the survey.

Records from the volcanic arc area with 4-km high conical edifices of basalt still contain much out-of-the-plane energy reflected from the complex, three-dimensional seafloor.

Migrations

Great variations in water depth meant that migration and depth conversion were critical in determining the true dip and geometries of observed reflectors. Various combinations of pre- and post-stack time and depth migrations improved key parts of both sections. Pre-stack depth migrations (Fig. 5) using depth focusing techniques to determine optimum migration velocities [Denelle et al., 1986] provided more accurate geometries as well as velocity templates for migrations of nearby parts of the sections.

Older refraction profiles provided additional velocity constraints for both the Banda Sea and Timor Trough areas [Bowin et al., 1980]. In addition, the southern ends of both sections lie on the Australian continental shelf and tie directly to an exploration well that penetrated Permian to Recent marine sediments lying unconformably on granite encountered at a depth of 3315 m (Fig. 6). The recent grid of deep seismic profiles collected on the Australian shelf provides further ties to numerous wells in the area [e.g. O’Brien et al., 1993] and also confirms that reflections described here represent regionally significant features.

The sections migrated using depth focusing to estimate migration velocities [Denelle et al., 1986] provide the most precise velocity estimates available to this study at present.

The section from the volcanic arc produced velocities within the volcanic cones and upper two kilometres of the arc crust from 2.0 to 4.2 km s-1 (Fig. 5B). These apparently low velocities for 0-3 Ma basaltic pillow lavas compare closely with velocities for similar rocks within the upper 600 m of mid-ocean ridges [Moos & Marion, 1994, and references therein]. In these studies, zero-age velocities of 2.0 km s-1 and porosities of 20-40% varied to velocities of 4-5 km s-1 and porosities of ~10% for 7.5 Ma pillow lavas.

The low velocities were attributed to high compliance of the contacts between pillows, pillow fragments and radial cooling cracks. The relatively rapid increase of velocity with age was welding of pillow contacts and cementing of the radial cracks and voids by low temperature alteration products [Moos & Marion, 1994].

The pre-stack depth migration of the section across the Timor trough produced clearer reflector targets for the velocity focusing analysis, and thus more reliable velocities than those from the volcanic arc (Fig. 6A). The velocities are again very consistent with recent studies across other accretionary wedges [e.g. Westbrook, 1991; Yuan et al., 1994] and imply porosities ranging from 50% to 10% at the top and the base of the Mesozoic sedimentary sequence south of the trough. North of the trough the velocities are less clearly defined due to the complex structure within the accretionary wedge. The lack of a continuous reflector at the base of the accretionary wedge provides no target for analysis of the effects of lateral velocity variations over short distances on continuity of deeper reflectors. Such analysis on the Cascadia accretionary wedge showed that velocity within a given stratigraphic horizon increased by 16-24% approaching the deformation front, and within the wedge velocities varied laterally over distances of 2-3 km by as much as 800 m s-1(20%) across through-cutting thrusts [Yuan et al., 1994].

Such velocity variations had noticable effect on deeper reflectors. No through-cutting thrusts are observed in the Banda arc sections, so lateral velocity variations are assumed to be much smaller and more continuous (Fig. 5A) than for Cascadia.

Interval velocity analysis

The velocity templates derived from optimizing the pre-stack depth migrations, average crustal velocities from the regional refraction studies, and well-log velocities from the Australian shelf all provided independent constraints in determining stacking velocities. Stacking velocities were required to maximize reflector coherency while producing interval velocities consistent with the independent constraints.

The low velocities associated with the thick water layer provided the necessary sensitivity in NMO to two-way travel times of 9-11 5, equivalent to 20 km depths. Consistent patterns of variation in interval velocities with depth allowed extrapolation of velocity structure along the profile between refraction surveys and drill holes (Fig. 7).

Interval velocities from the northern half of the DAMAR profile required a consistent and distinctive increase from <6.5 km ~4 to >7.5 km ~4 at 8-20 km depths in order to maximize reflectivity in the stacks (Fig. 7). Such an increase is consistent with the refraction results from the nearby Banda Sea and indicates oceanic lithospheric structure with Moho at 14f6 km depth [Bowin et al., 1980]. On the TIMOR line this transition occurs deeper, between 10 and 35 km, possibly because the northern part of this line follows a line of seamounts. These values are typical of oceanic and not continental crustal structure in this region [Bowin et al., 1980; Silver et al. 1985].

Continental crustal velocity structure is displayed by the interval velocities of both profiles where velocities >7.5 km ~4 do not consistently occur at depths less than 30 km (Fig. 7).

 STRUCTURES FROM SEISMIC REFLECTOR GEOMETRIES

The Timor Sea and northern margin of the Australian continental shelf

The shallow parts of the new seismic sections show features reported from previous shallow seismic sections from the Timor Sea and Timor Trough area: a breakup unconformity dividing the shelf sedimentary section into a faulted and tilted Early Jurassic and older part and a sub-horizontal Late Jurassic and younger passive-margin sequence, with overlying outer-slope strata within the trough (Figs. 6 & 8) [Karig et al., 1987, Fig. 7 AB]. In the immediate region of the deep seismic profiles, two logged wells allow identification of prominent reflectors with rock units and extrapolation of units unconformity provides a clear reflector on the shelf. It is not angular, only; gradual pinchouts of seismic sequences indicate its presence (Fig. 7).

The outer slope strata include shales and limestones forming slides as described by Karig et al. [1987] and layered sequences as described by Johnston and Bowin~[1981]. Some normal faults cut the slide deposits to form bathymetric scarps; others offset deeper strata, but do not effect the more recent deposits (Fig. 8).

In addition to these normal faults and structures related to the Mesozoic rifting of the Australian margin [e.g. Powell, 1982; O’Brien et al. 1993], at least three more recent deformations can be inferred from reflectors observed on the deep sections. These deformed reflectors occur in both the sedimentary sequence and in the presumed metamorphic basement beneath Permian strata. Deformation postdating the slope slides include a block rotation near the shelf margin side of the trough (2 in Pig. 8), the shelf side of the block rotated upward to create normal offsets in the Permian-Recent sediments. An antiform of reflectors 10 km wide that is broken by kink-bends occurs immediately beneath the upturned edge of the block within the basement.

The next youngest deformation forms a deeper and wider antiformal pattern in the basement, and its northern limb appears to truncate the shallower structure (3 in Fig. 8).

This deformation appears to have folded a reflector associated with the outer-slope slide. It uplifted a block of the overlying shelf sequence within a horst structure that is bordered on the trench side by a normal fault that continues to the seafloor to form a scarp. This scarp and the folded reflector associated with the slide scarp are observed on the TIMOR section, but not on the DAMAR section where several linear, trenchward dipping reflectors project to the surface near the shelf margin (Fig. 3).

The most recent deformation is recorded by horizontal sedimentary layers in the floor of the trough (4 in Fig. 8). These_reflectors apparently record ongoing horizontal shortening: the toe of the accretionary complex has partly overthrust these seafloor sediments on the TIMOR section, section whereas an asymmetric fold occurs in these layers on the DAMAR section (Fig. 3). Similar anticlines that are -4 continuous for only tens of kilometers were documented south of western Timor, and inferred to indicate ongoing accretion of the youngest sediments [Karig et al., 1987].

A small-scale interfingering of reflectors occurs in both sedimentary sequence and basement, but cannot be related directly to the other structural geometries. At several locations within the shelf sequence, these 1~ km wide sub-vertical deformation zones barely resolve into thrusts and wedges of strata that appear to represent a few hundred meters of localized shortening (SPs 6650 & 6930 on Fig. 8). A similar angular truncation of reflectors occurs at 10-15 s on both deep sections (Fig. 9). Such angular relations between basement reflectors are cryptic, but are with zones of horizontal shortening in many places [e.g. Meissner, Wever & Sadowiak, 1991].

Continuous reflector segment and amplitudes are greatest beneath the sediments at times of 10-15 5 on both profiles. These deep reflection geometries occur at Moho depths based on extrapolation onto the reflection sections of velocities from older refraction surveys nearby in the Timor Trough and near the Australian coast [Bowin et al., 1980]. Taken together, these seismic observations indicate a 30-35 km thick crust. On the DAMAR line and other recant deep seismic lines [C. J. Pigram, unpub. data] one group of prominent reflections dip northward from 15 s beneath the shelf margin, and apparently represent a mantle reflector.

The deep reflection profiles have borth confirmed previous observation about near surface reflectors and revealed new basement reflections adjacent to near-surface deformation zones. Beneath the faulted sedimentary sequence, numerous arcuate and linear reflectors are observed throughout the basement of the Australian shelf at least as deep as the Moho and as far north as the axis of. the present-day trough. Many of these reflectors are offset, displaced or truncated at moderate (10~40o) angles by other reflectors. Geometries usually associated with horizontal shortening supercede those usually associated with horizontal extension, where superposition relationships are observed (Fig. 8)

The accretionary complex near Timor

 Prominent reflections associated with the Mesozoic shelf sediments can be correlated at least 10-20 km north of the axis of the Timor Trough (Figs. 8 &9). On migrated versions of the TIMOR section some reflectors can be followed for nearly 50 km as they arc through several antiforms, but appear offset in places. On the DAMAR line a similar fold appears in the axis of the trough but within the toe of the accretionary wedge thrust-sense offsets predominate (Fig. 3). Both reflection patterns are common in accretionary prisms and foreland fold-and-thrust belts worldwide [e.g. Price, 1981; Boyer & Elliot, 1982; Westbrook et al., 1988; von Huene et al., 1994].

Although the seismic sections have been migrated and depth converted using all velocities available, as described previously, strong lateral gradients in velocity could cause apparent dips in underlying reflectors. A velocity change from 2.0 to 2.2 to 2.0 km

s-1 over a horizontal distance of about 5 km could produce the anticline structure observed. Velocity changes of this magnitude have been observed in active accretionary prisms as fluids migrate through the prism [Westbrook, 1991; Yuan, Spence & Hyndman, 1994, and references therein]. Prestack depth migration velocities provided no seismic evidence of pressure waves near Timor and consistent distortions of reflections are not observed in the deeper and wider parts of the seismic section.

On theother hand, fold structures are consistent with field observations from the island of Timor [Charlton et al., 1991; Harris, 1991].

Geologists hypothesize the development of a sequence of fold and thrust structures within the accretionary complex near the Timor Trough by which the youngest sedimentary rocks are deformed in the toe of the accretionary complex, whereas older strata are underthrust intact beneath the complex before becoming folded and faulted and thickened, eventually to emerge at the surface much further north [Karig et al., 1987; Charlton et al., 1991; Harris, 1991]. Near the north coast of Timor the Aileu Formation consists of psammites, marbles, lherzolites and moderately metamorphosed Permian-Jurassic strata [Dropkin, 1993]; these rocks probably represent the part of the Australian shelf incorporated into the accretionary complex that includes Timor and nearby islands, at the earliest stage in the collision.

The semi-continuous reflections observed within the accretionary complex do not confirm these tectonic models, but are certainly consistent with ~hem. Geologic mapping on the island of Timor is complicated by the lack of continuity of a given rock unit in outcrop; most units are isolated by the matrix of the Bobonaro Scaly Clay unit in which the other blocks appear to float. The Bobonaro &aly Clay has most recently been interpreted as shale diapirs and mud volcanoes [Barber et al., 1986]. These features are common throughout the island of Timor, and probably equally common on the seismic reflection sections where they would appear as zones of strongly disrupted reflections [e.g. Westbrook & Smith, 1983].

Deeper than ~20 km and more than 50 km away from the trough, the accretionary complex does not appear to have any preferred orientation of reflections except near its northern margin, where the forearc ridge of the Outer Banda Arc gives way to the forearc basin (Fig. 4). Within 1()~20 km of this relatively steep bathymetric slope, southward-dipping reflections appear on migrated sections (Fig. 10).

The submarine ridge that appears on the TIMOR section is the assumed along-strike structure of the nearby island of Kisar. Recent mapping on the island of Kisar has revealed, from south to north, low-grade metamorphic rocks such as greenstones, amphibolites, and bands of thick mylonitized quartzites interlayer with grindstones and high-grade pelites. These rocks resemble the Lolotoi and Mutis Formations on Timor [Dropkin, 1993], but have some similarities to the Aileu Formation on Timor [Berry & Grady, 1981] and to rocks on Moa [Richardson, 1993) in their lithology, deformation, and metamorphism.

The island of Kisar and neighboring parts of the accretionary complex are pervasively cut by southward dipping reflectors. Offsets in basement reflections and in the basin sediments point to thrust movements with top to the north sense (Fig. 10). These features are clearest, and therefore presumed recently active, beneath the Kisar ridge, but are also observed within the northern part of the main accretionary complex as well (Fig. 3). Such structures in similar settings are interpreted as backthrusts that form the backstop to the accretionary wedge [Silver & Reed, 1988].

The Banda volcanic arc

The Inner Banda Arc is composed almost entirely of basaltic rocks of volcanic origin, a  few local basins have several hundred meters of recent sediments. Within the segment traversed by the deep seismic profiles the arc has remained active to the east, near Damar, and has been inactive for nearly 3 Ma to the west, near Romang and Wetar [Abbott & Chamalaun, 1981]. Its characteristic seafloor of conically shaped volcanic constructs composed of porous basalt with little sedimentary cover make it a particularly challenging crustal seismic target. The reflection data were acquired in order to image the lithosphere at 40-120 km depths and to correlate reflectivity with local earthquake hypocenters [M&affrey et al., 1985; McCaffrey & Nabelek, 1986; McCaffrey, 1988]. These earthquake studies included fewer than 10 well-constrained focal mechanisms analyzed in conjunction with older single-channel reflection profiles that provided information limited to less than 1 km depth below the seafloor [Silver et al., 1983]. These two diverse and sparse data sets fueled hypotheses that plate convergence of as much as 1 cm a-1 and a cumulative 10 km of displacement might be accommodated at the northern margin of the volcanic arc on southward dipping thrusts [McCaffrey, 1988], collectively termed the Wetar Thrust [Silver et al., 1983]. It was assumed that use of a source 15 times larger than that used previously would produce clearer reflections from any potential basement thrusts in the crust.

The two new deep reflection profiles cross the trace of the Wetar Thrust at localities near, but not coincident with the older shallow profiles of the RAMA 12 cruise (Fig. lB) [Silver et al., 1983]. Neither deep section shows disrupted sediments such as those used to define the thrust zone on the older, shallow section, but both deep sections show southward-dipping reflections with clear indicators of thrusting. On the TIMOR section the Wetar Thrust projects along the axis of a short east-west valley (Fig. 1B) which has a U-shaped cross section after migration and depth convertion (Fig. 11). Truncated, antiformal reflectors appear south of this valley, suggesting over 4 km of deformed basement beneath a thin mantle of recent sediments. Similar relationships are observed on the DAMAR line, but here the southward-dipping reflections project into the side of active volcanic edifice that makes the island of Damar (Fig. 5B). Linear reflections intersect the seafloor at clear scarps, -250 m high, that are improbable as lava flow fronts. Up to 750 m of deformed sediments may underlie the bathymetric low near Damar, but little sediment cover is evident on the slopes of the volcanoes themselves (Figs. 8B & 11). The offsets on possible faults are indeterminate, but unlikely to exceed a few kilometers because the reflections cannot be traced with any confidence deeper than 6-10 km.

Reflections along the southern margin of the Inner Banda Arc are less well defined near the seafloor. Little evidence of sediments is observed except within the forearc basin where <500 m of layered strata dip gently to the south and show little indication of deformation except within 2 km of the arc where a slight increase in seafloor slope occurs (Fig. 12).

On TIMOR few basement reflections are continuous and the sense of the offsets is indistinct. Where a few clear thrusts are observed near the top of the arc slope, the fault surfaces appear to have been folded by subsequent vertical uplift and thickening within the basement. Shallow reflections are equally indistinct on the DAMAR line although two bright and more continuous reflections are observed at 11- 13 and 17-19 km depths. The forearc basin is only 12 km wide here and the deep, generally northward dipping reflections project to, but do not reach, the seafloor near its axis (Figs. 12 & 13). These reflections appear to dip through most of the crust and at least several kilometers into the uppermost mantle beneath the volcanic arc if estimates The southern Banda Sea has typical oceanic lithospheric structure based on the available refraction results [Bowin et al., 1980] and geological studies [Silver et al., 1985).

The refraction profiles indicate tens of metres of pelagic sediments at 4-5 km water depths (Fig. 14). Interval velocities from the DAMAR line suggest Moho at ~12 km depth, whereas those from the TIMOR line velocities indicate a crust ~25 km thick beneath a line of seamounts and seafloor lava flows (Figs. lB & 7). No consistent reflectivity is observed within the crust of the back-arc region.

A LITHOSPHERIC PERSPECTIVE

 In addition to better definition of uppermost crustal structures within each of the parallel zones making up the Banda Arc, the deep seismic reflection profiles also help to characterize deformation of the lithosphere as a whole and the role of elastic flexure of the Australian margin.

Horizontal shortening appears distributed over a 200-km-wide plate boundary zone [e.g. England & Jackson, 1989], with individual structures becoming active for relatively short periods over short segments of the arc and internal block rotating along these structures. Unusually, this wide deformation embraces both continental and oceanic lithosphere in the Banda Arc.

The steep bathymetric slope associated with the northern margin of the Outer Banda Arc accretionary complex coincides with the strongest Bouguer or Free-air gravity gradient in the region [Bowin et al., 1980; Milsom & Audley-Charles, 1985] and a distinct change in the interval velocities used to optimally stack the reflection sections.

Interval velocities increase from ~6.5 to ~8.0 km s-1 between 12 and 18 km depths north of this area, but at >25 km to the south (Fig. 7). The coincidence of the velocity change, the gravity gradient and increased diversity of rock types to the south in geologic observations is consistent with the location of a boundary between oceanic crust and lithosphere to the north and continental crust to the south [e.g., McBride & Karig, 1988; Jongsma et al., 1989].

Elastic flexure of the Australian lithosphere

 The loading of the Australian shelf by both the accretionary complex and oceanic crust is an obvious candidate for elastic flexural modeling. Preliminary two-dimensional studies done without any geometries derived from seismic reflection data indicate that trench axis depths of 2 km and the position of the shelf break can be matched using an elastic thickness of 25 km loaded by a wedge 100 km wide with a 10 km maximum thickness [Lorenzo et al., 1993]. This modeling also predicted a 300-m bathymetric arch which is not observed on the Australian shelf. The failure of this prediction suggests non-elastic behavior or deformation of the lithosphere, consistent with deformation indicated by reflector geometries observed on the deep profiles (Fig. 8). Thrust imbrication at crustal and possibly uppermost mantle levels of the Australian lithosphere can destroy the flexural integrity of the lithosphere and causes it to behave in a non-ideal manner. The apparent disappearance of lower crustal reflections north of the trough suggests a lack of lateral continuity in the physical properties of the downgoing Australian lithosphere1 probably due to either deformation or metamorphic grade increasing at greater depths.

Possible uplift mechanisms for the Inner and Outer Arcs

 Coral terraces on Wetar and stratigraphic logs from sedimentary basins in central Timor  indicate that both the Inner and Outer Banda arcs continue to emerge from the sea in the area of the new reflection profiles. Reflectors on these profiles dip in toward the axis of each arc from both of their margins. Bathymetric scarps and nearby arcuate reflectors consistently indicate thrust sense offsets along these reflectors. The uplift and foldthrust shear zones inferred from these reflector geometries are consistent with thosepredicted by a series of plane-strain finite-element models collaborated by sandbox simulations [e.g. Beaumont & Quinlan, 1994, and references therein].

The lack of two-dimensional refraction velocity models preclues complete definition of the Moho along the reflection profile1 and therefore singularity points used in the numerical models where mantle lithosphere converges cannot be precisely defined for The apparent dual convergence within the crust during the past 3 Ma, as indicated by two doubly vergent zones, suggests that the location of mantle convergence may be migratiAg and polarity possibly reversing (Fig. 15).

this interpretation, the volcanic arc represents a symmetric orogen in the first stage of evolution [Willet et al., 1993] and implies a juvenile mantle subduction zone directly beneath the arc. The asymmetry of the accretionary complex comprising the Outer Banda arc resembles isostatically adjusted, mature orogenic belts [stage 3 of Willet et al., 1993].

The relative locations of the accretionary complex, the Timor Trough, and the deep Wadati-Benioff zone suggest that deep mantle subduction zone earthquakes locate mantle convergence associated with crustal convergence observed on seismic profiles across the Timor Trough. The paucity and scattered occurrence of earthquakes shallower than 100 km possibly result from a gradual transfer of strain northward from predominantly beneath the Outer Banda arc to beneath the inactive volcanic arc as suggested by several previous studies [McCaffrey, 1988; Masson et al., 1991].

Figure Captions

Table 1. Stratigraphic units of the Australian shelf and Timor

Figure 1.

(A) Regional location map showing the principal landmasses, the 200m bathymetric contour that approximately defines the limit of the continental shelf, the 3000 m contour that approximates the limits of oceanic crust in the Indian Ocean, the new seismic reflection lines (heavy solid lines), older refraction profiles (medium solid lines), and the volcanoes (triangle if active, square if inactive) where He isotope ratios indicating the limit of subducted continental crust were measured (dashed line) [Hilton et al., 1993]. Also shown are the location of three temporary seismic stations (pentagons) [I.

Reid, unpublished data 1993]. The vector labelled 7.5 cm a-1 represents the local relative convergence vector between Australia and Eurasia [DeMets et al., 1990]; other vectors indicate recent displacements measured by CPS relative to the circle indicated at latitude 40s, longitude 1220E [Cenrich et al., 1993]. The circle labelled 262 indicates a DSDP hole.

(B) Location of major known submarine features and the new seismic lines TIMOR, API, and DAMAR. Dashed lines indicate older scientific expeditions in this area. The Troubadour well (solid dot) on the Australian shelf margin [Australian Geological Survey Organisation, unpublished data] is located at SP 7995 of the ~MOR line. On land areas shaded in black contain exposures of ophiolites.

Figure 2. Cartoon cross sections showing three models, each hypothesized to explain various observations made near Timor.

Figure 3. Cartoon interpretation of the DAMAR deep seismic section incorporating small earthquakes (open circles) with epicentres within 25 km of the seismic lines [I. Reid, unpublished data, 1993], teleseismic earthquakes greater than mb=5 (solid circles) with epicentres within 50 km of the seismic lines, and large teleseismic earthquakes with published focal mechanisms [McCaffrey, 1988] and with epicentres within 50 km of the seismic lines. Focal mechanisms are projected onto the plane of the section, dark quadrants represent compression. The dashed line labelled Moho is inferred from the two local refraction profiles (Fig. 4) [Bowin et al., 1990], interval velocities in the north, lower crustal reflectivity in the south, and regional gravity models made along this profile. The stippling indicates Mesozoic shelf sediments of the Australian margin.

Figure 4. Line drawings of the three deep seismic reflection profiles used in this study. Each section has been migrated at water velocities before line drawings were made.

Figure 5. Pre-stack depth migrated seismic sections using the velocity field shown at the bottom, both produced using the algorithm of Denelle et al. [1986].

(A) Section near the Timor Trough (DAMAR line). (B) Section just north of the volcano Damar where the proposed Wetar Thrust crosses the section (DAMAR line). Two scarps visible in the dipping seafloor on the flank of the volcano and reflectors starting at these scarps and dipping southward to -5 km depths suggest possible thrust faults.

Figure 6. Shallow part of the deep seismic profile AGSO Line 12 from the Australian shelf (Fig. IA). The well picks indicate that the Jurassic “Breakup Unconformity” is a prominent and continuous reflector at ~1.8 s.

Figure 7. Interval velocities determined during stacking of the reflection data and tied to available well and refraction surveys (Fig. 1). The northern parts of the profiles show an increase to typical mantle velocities at shallower depths than do the southern parts of the profiles.

Figure 8. Part of the TIMOR seismic reflection section near the Timor Trough. This section was migrated using -80% of the stacking velocities. The diagram below shows the interpreted sediment layers tied to the nearby well, and numbers indicate inferred deformation within both the sediments and the underlying basement. Dl is normal faulting producing -200 m displacement at the bathymetric scarp (SP 7205). D2 deformation includes counterclockwise rotation of the block beneath the Timor Trough related to folding at depth (SP 6400~500). D3 horizontal shortening within the inferred basement at 6-9 5 results in folding of Dl at 6 5 and uplift of overlying sediments within a horst block (SP 6800). D4 faulting thrusts the toe of the accretionary complex over recent, flat-lying sediments in the trough.

Figure 9. Deeper part of the migrated seismic section Figure 8 with different display parameters. Post-Permian shelf sediments are clearly seen near the seafloor on the inner trough wall, deformed beneath the trough floor and outer trough wall. Two northward reflectors are indicated as shear zones with top-to-the-south sense of shear. Combined with the southward dipping reflector, these shears are interpreted as defining wedging within the lower crust of the Australian shelf.

Figure 10. Part of the TIMOR seismic reflection section just south of northern margin of the accreted arc where the profile crosses a submarine ridge near the island of Kisar (Fig. 4). This section was depth migrated after stacking. A southward dipping reflective zone shown on the interpreted line drawing appears to underlay the metamorphic rocks of Kisar, truncation relationships between reflectors near the seafloor in sediments and within the basement suggest several thrust faults.

Figure 11. Part of the TIMOR seismic reflection section and interpretative line drawing, located just south of northern margin of the volcanic arc where the profile crosses the Wetar Thrust. This section was depth migrated after -stacking using 80% stacking velocities. Several reflectors are truncated downward into a prominent south-dipping reflector that may represent the Wetar Thrust in this area.

Figure 12. Part of the TIMOR seismic reflection section just south of southern margin of the volcanic arc. This section was depth migrated after stacking. Several reflectors are shown on the interpetative line drawing to dip northward from the arc margin where 100-300 m of sediments lap, undeformed, onto the arc margin.

Figure 13. Part of DAMAR section showing the volcanic arc and reflectors (arrows) dipping northward and southward from both margins down to 11-15 s travel time. This section was migrated at water velocity.

Figure 14. Part of the TIMOR seismic reflection section just south of Gunung Api. This section was migrated and then depth converted using the velocities shown at the right in km s-1. In this depth section the Moho appears as a bright reflection at a depth of 10 km where this line crosses the API line. If the refraction velocity function M12 of Bowin et al. [1980), shown at the left for comparison only, is used for depth convertions, the brightest subhorizontal reflections occur at 14-15 km mantle depths, and no obvious feature can be associated with the Moho. M indicates numerous convex upward reflections that are migration noise due to the incomplete removal of the seafloor multiple before migration.

Figure 15. Cartoons showing stages 1 & 3 from the doubly-vergent orogen tectonic models of Willet et al. [1993]. Here these models based on finite element calculations assuming plane strain are applied to the Inner and Outer Banda Arcs, respectively, and appear to match the general seafloor morphology whereas regions of higher strain predicted by the models correlate in shape and location with regions of dipping reflections.

REFERENCES

Abbott, M. J., & F. H. Chamalaun, Geochronology of some Banda Arc volcanics, in The geology and tectonics of eastern Indonesia, Geol. Res. & Dev. Centre Spec. Publ., 2, 253- 268, 1981.

Audley-Charles, M. C., Timor-Tanimbar Trough: the foreland basin of the evolving Banda orogen, in Allen, P.A., & Homewood, P. (eds.), Foreland Basins, Spec. Pub. Int.Assoc. Sedimentologists, 6, 91-102, 1986.

Barber, A. J., M. C. Audley-Charles, & D. J. Carter, Thrust tectonics in Timor, I. Geol. Soc. Australia, 24, 51-62, 1977.

Barber, A. J., S. Tjokrosapoetro, & T. R. Chariton, Mud volcanoes, shale diapirs, wrench faults and melanges in accretionary complexes, eastern Indonesia, Am. Ass  Petroleum Geol Bull.., 70, 1729-1741, 1986.

Beaumont, C., & G. Quinlan, A geodynamic framework for interprefing crustal scale seismic reflectivity patterns in compressional orogens, Geophys. J int., 116, 754-783,1994.

Berry, R. F., & A. F. Grady, Deformation and metamorphism of the Aileu Formation, north coast, East Timor and its tectonic significance, J. Strict. Geol., 3, 143-167, 1981.

Berry & McDougall, 1986. Bowin, C., G.M. Purdy, C. Johnson, C. Shor, L. Lawver, H. M. S. Hartono, & F. Jezek, Arc-continental collision in the Banda Sea region, Am. Assoc. Petroleum Geol. Bull.., 64, 868-915, 1980.

Boyer, S. F., & D. Elliot, Thrust Systems, Am. Assoc. Petroleum Geol. Bull., 66, 1196-1230, 1982.

Breen, N. A., F. A. Silver, & S. Roof, The Wetar backthrust belt, eastern Indonesia: the effects of accretion against an irregularly shaped arc, Tectonics, 8, 85-98, 1989.

Brunnschwejler, R. 0., Note on the geology of eastern Timor, Bur. Mm. Res. Australia Bull., 192, 9-18, 1978.

Cardwell, R. K., & B. L. Isacks, Geometry of the subducted lithosphere beneath the Banda Sea in eastern Indonesia from seismicity and fault plane solutions, J. Geophys. Res., 87, 2825-2838, 1978.

Carter, D. J., M. G. Audley-Charles, & A. J. Barber, Stratigraphical analysis of island arc~ontinent margin collision in eastern Indonesia, J. Geol. Soc. London, 132, 179- 198, 1976.

Chamalaun, F. H., & A. E. Grady, The tectonic development of Timor: a new model and its implications for petroleum exploration, The APEA Journal., 18, 102-108, 1978.

Chamalaun, F. H., K. Lockwood, & A. White, The Bouguer gravity field and crustal structure of eastern Timor, Tectonophysics., 30, 241-259, 1976.

Chappell & Veeh, Geol. Soc. Am. Bull., 1978.

Charlton, T. R., A. J. Barber, & S. T. Barkham, The structural evolution of the Timor collisional complex, eastern Indonesia, J. Geology, 13, 489-500, 1991.

Cloetingh, S., & R. Wortel, Stress in the Indo-Australian plate, Tectonophysics., 132, 49-67, 1986.

Crostella, A. A., & D. F. Powell, Geology and hydrocarbon prospects of the Timor area, Indonesian Pet. Assoc. Proc.., 4 (11), 149-171, 1976.

De Smet, M. F.M., A. R. Fortuin, S. R. Troelstra, L. J. Van Marle, M. Karmini, S. Tjokrosapoetro, & S. Hadiwasastra, Detection of collision-related vertical

movements in the Outer Banda Arc (Timor, Indonesia), using micropaleontological data, J. SE Asian Earth Sci., 4, 337-356, 1990.

DeMets, C., Gordon, R. C., Argus, D. F., & Stein, S.. Current plate motions, Geophysical Journal International, 101, 425-478, 1990.

Denelle, F., Y. Dezard, & I. Raoult, 2-D prestack depth migration in the (S-G-W) domain,  extended abstract, 56th SEC Meeting, Houston, 1986.

Dropkin, M. J., Harris, R. A., & Zeitler, P. K., An Oligocene forearc crustal flake exposed in a contemporary arc-continent collision: Timor, Indonesia (abs.), Geological Society of America Annual Meeting, Abstracts with Programs, 25, A-482, 1993.

England, F., & J. A. Jackson, Active deformation of the continents, Ann. Rev. Earth Planet. Sci., 17, 197-226, 1989.

Genrich, I., Bock, Y., Calais, F., McCaffrey, R., Fauzi, C. S., Zwick, P., Puntodewo, S. S. 0., Rais, I., Subarya, C., Tregoning, P., & Brunner, F., Contemporary crustal deformation in Indonesia: Sumatra fault transects and Flores earthquake study (abs.), EOS, 74, 191, 1993.

Grady, A. E.,& R. F. Berry, Some Paleozoic-Mesozoic stratigraphic-structuralrelationships in east Timor and their significance in the tectonics of Timor, J. Geol. Soc. Aust., 24, 203-214, ~977.

Hamilton, W., Tectonics of the Indonesian region, U. S. Geol. Surv. Prof. Paper., 1078, 345 pp., 1979.

Hamilton, W., Plate tectonics and island arcs, Geol. Soc. Am. Bull., 100, 150-527, 1988.

Hardy, R. J. J., and R. W. Hobbs, a strategy for multiple Suppression, First Break, 9, 159-144, 1991.

Harris, R. A., Temporal distribution of strain in the active Banda orogen: a reconciliation of rival hypotheses, J. SE Asian Earth Sci., 6, 373-386, 1991.

Hilton, D. R., Hoogewerff, J. A., van Bergen, M. J., & Hammerschmidt, K., Mapping magma sources in the west Sunda-Banda arcs, Indonesia: Constraints from helium isotopes, Geochimica et Cosmochimica Acta, 56, 851-859, 1993.

Hobbs R. W., & D. B. Snyder, Marine seismic sources used for deep seismic reflection profiling, First Break, 10, 417-426, 1993.

Jacobson, R. S., C. Shor, R. M. Kieckhefer, & G.M. Purdy, Seismic refraction and reflection studies in the Timor-Aru Trough system and Australian continental shelf, in Watkins, J. S., L. Montadert, & P. W. Dickerson (eds.), Geological and geophysical investigations of continental margins, Am. Assoc. Petroleum Geol. Mem.., 29, 209-222, 1978.

Johnston, C. R., & C. O. Bowin, Crustal reactions resulting from the mid-Pliocene to recent continental-island arc collision in the Timor region, Bur. Mm. Resour. J. Austr. Geol. Geophys., 6, 223-243, 1981.

Jongsma, D., J. M. Woodside, W. Huson, Suparka S., & D. Kadarisman, Geophysics and tentative late Cenozoic seismic stratigraphy of the Banda Arc-Australian continent collision zone along three transects, Neth. J. Sea Res.., 24, 205-229, 1989.

Karig, D. E., A. J. Barber, T. R. Charlton, S. Kiemperer, & D. M. Hussong, Nature and distribution of deformation across the Banda Arc-Australian collision zone, Geol. Soc. Am. Bull., 98, 18-32, 1987.

Kirby, S., & B. Hacker, Earthquakes at the deep roots of arc volcanoes, EOS, 74, 70, 1993. Lorenzo, I. M., K. Tandon, & R. Boehme, Pliocene flexural extension over the Vulcan Sub-basin (Timor Sea, North West Shelf, Australia): observations and elastic modeling (abs.), EOS, 7X, 1993.

Masson, D. D., I. Milsom, A. J. Barber, N. Sikumbang, & B. Dwiyanto, Recent tectonics around the island of Timor, eastern Indonesia, Mar. & Pet. Geol., 8, 35-49, 1991.

McBride, J. H., & D. E. Karig, Crustal structure of the outer Banda arc: new free-air gravity evidence, Tectonophysics, 140, 265-273, 1987.

McBride J. H., R. W. Hobbs, T. J. Henstock, & R. S. White, On the “wrap-around” multiple problem of recording seismic reflections in deep water, Geophysics, 59, 1160-1165, 1994.

McCaffrey, R., P. Molnar, S. W. Roecker, & Y. S. Joyodiwiryo, Microearthquake seismicity and fault plane solutions related to arc-continent collision in the eastern Sunda Arc, Indonesia, I. Geophys. Res., 90, 4511~528, 1985.

Mccaffrey, R.,& Nabelek, Seismological evidence for shallow thrusting north of the Timor trough, Geophys. J. R. Astron. Soc., 85, 365-381, 1986.

Mccaffrey, R., Active tectonics of the eastern Sunda and Banda Arcs, I. Geophys. Res., 93, 15163-15182, 1988.

Milsom, J., & M. C. Audley-Charles, Post-isostatic readjustment in the southern Banda Arc, in Coward, M. P., & Ries, A. C. (eds.), Collision tectonics, Spec. Pub. Geol. Soc. London, 19, 353-364, 1985.

Meissner, R., Th. Wever, & P. Sadowiak, Continental collisions and seismic signature, Geophys. I. int., 105, 15-23, 1991.

Montecchi, P. A., Some shallow tectonic consequences of subduction and their meaning to the hydrocarbon explorationist, in M. T. Harbouty, J.C. Maher & H. M. Lian (eds.), Circum-Paciflc Energy and Mineral Resources, Mem. Am. Assoc. Pet. Geol., 25, 189-202, 1976.

Moos, D., & D. Marion, Morphology of extrusive basalts and i{5 relationship to seismic velocities. in the shallow oceanic crust, J. Geophys. Res., 99, 2985-2994, 1994.

O’Brien, C. W., M. A. Etheridge, J. B. Wilcox, M. Morse, P. Symmonds, C. Norman, & D. I. Needham, The structural architecture of the Timor Sea, northwestern Australia: implications for basin development and hydrocarbon exploration, Australian Petrol. Explor. Assoc. J., 33, 258-278, 1993.

Pigram, C. 1.~ P.1. Davies, D. A. Feary, & P. A. Symonds, Tectonic controls on carbonate platform evolution in southern Papua New Guinea: passive margin to foreland basin, Geology., 17, 199-202, 1989.

Pigram, C. J., & H. Panggabean, Rifting of the northern margin of the Australian continent and the origin of some microcontinents in eastern Indonesia, Tectonophysics., 107, 331-351, 1984.

Powell, D. F., The northwest Australian continental margin, Phil. Trans. R. Soc. London, A305, 45-62, 1982.

Price, R. A., The Cordillera foreland thrust and fold belt in the southern Canadian Rocky Mountains, in N. J. Price (ed.), Thrust nappe tectonics, Sp. Pub. Geol. Soc. London ,9, 1981.

Richardson, A., PhD thesis, University of London, 1994. Schluter, H. U., & J. Fritsch, Geology and tectonics of the Banda Arc between Tanimbar Island and Aru Island (Indonesia)-results of R/V Sonne Cruise So-16, Geol. Jahr. Reihe F, 30, 44p., 1985.

Silver, E. A., & D. L. Reed, Back arc thrusting in accretionary wedges, I. Geophys. Res.., 93, 3116-3126, 1988.

Silver, E. A., J. B. Gill, D. Schwartz, H. Prasetyo, & R. A. Duncan, Evidence for a submerged and displaced continental borderland, north Banda Sea, Indonesia, Geology., 13, 687~91, 1985.

Silver, E. A., D. Reed, R McCaffrey, & Y. Joyodirwiryo, Back arc thrusting in the eastern Sunda arc, Indonesia: a consequence of arc-continent collision, J. Geophys. Res.., 88, 7429-7448, 1983.

Sopaheluwakan, PhD thesis, University of London, 1990.

Veevers, J. J., Phanerozoic Earth history of Australia, Oxford Monographs on Geology and Geophysics, 2, Oxford University Press, Oxford, 418 p., 1984.

Veevers, J.J., D. A. Falvey, & S. Robins, Timor Trough and Australia: facies show topographic wave migrated 80 km during the past 3 m.y., Tectonophysics., 45, 217- 227, 1978.

Von der Borch, C. C., Continent-island arc collision in the Banda Arc, Tectonophysics, 54, 169-193, 1979.

Von Huene, R., D. Klaeschen, B. Cropp, & J. Miller, Tectonic structure across the accretionary and erosional parts of the Japan Trench margin, J. Geophys. Res., 99, 10000-XXXX, 1994.

Westbrook, C. K., Geophysical evidence for the role of fluids in accretionary wedge tectonics, Phil. Trans. R. Soc. London, A335, 228-242, 1991.

Westbrook, C. K., & M. I. Smith, Long decollements and mud volcanoes: evidence form the Barbados Ridge complex for the role of high pore-fluid pressures in the development of an accretionary complex, Geology, 11, 279-283, 1983.

Westbrook, G. K., I. W Ladd, P. Buhl, N. Bangs, & C. J. Tiley, Cross section of an accretionary wedge: Barbados Ridge complex, Geology, 16, 631~35, 1988.

Willet, S., C. Beaumont, & P. Fullsack, Mechanical model for the tectonics of doublyvergent compressional orogens, Geology, 21, 371-374, 1993.

Yuan, T., C. D. Spence, & R. D. Hyndman, Seismic velocities and inferred porosities in the accretionary wedge sediments at the Cascadia margin, J. Geophys. Res., 99, 4413-4427, 1994.