Abah, Dalam kasus LUSI, lumpur dan gas yang tersembur itu bukan merupakan akumulasi yang berasal dari sedimen yang terperangkap di zone subduksi seperti ditulis jurnal tersebut. Kita tahu, lumpur dan gas itu berasal dari zone depresi Kendeng yang sedimennya diendapkan dengan sangat cepat sehingga memicu diapirisme, diapirisme memicu mud volcano, mud volcano tererupsi karena dipicu gempa atau kegiatan pemboran. Tetapi, kalau untuk kasus gunung-gunung lumpur di Sawu Basin di utara Pulau Sawu (dekat Sumba-Rote), kalau Abah pernah lihat beberapa seismic sections di Sawu Basin, di situ banyak gunung2 lumpur bawah laut. Nah, ini adalah memang berasal dari sedimen yang terakumulasi di zone subduksi, dan erupsinya didorong oleh kompresi dari thrust sheets yang banyak terbentuk di melange wedge Sawu-Rote-Timor. salam, awang [EMAIL PROTECTED] wrote: Kang Awang.
Re- keterangan diatas , bagaimana mengaplikasikan - nya dalam kasus Sidoarjo ? Apakah posisi subduction zone dan saat sedimentasi mendukung pendapat diatas ? Kelihatannya kita harus melihat dan belajar dari kejadian kejadian di - region lain untuk menambah data sebelum suatu kesimpulan final dicapai. Hal ini penting SEKALI karena akan menyangkut suatu keputusan Pengadilan dalam banyak "pengaduan dari masyarakat". Si- Abah [EMAIL PROTECTED] wrote: > Coba kita tengok bagaimana jurnal-jurnal ilmiah luar negeri mengulas LUSI > ini. Saya mengamati beberapa, dan ternyata semua sama yaitu bahwa mereka > hanya sepakat bahwa Lusi adalah "mud volcano eruption" Apa penyebab > erupsinya ? Gempakah, pengeboran Lapindokah ? Tak tahu. Besar kemungkinan > dua-duanya. Sebuah jurnal menyebutkan juga gejala geotermal. Di bawah ini > adalah salah satunya. > > Salam, > Awang > > > Mud volcano floods Java > > > Disaster-plagued Indonesian island faces new threat. > > by Richard Van Noorden > [EMAIL PROTECTED] > What Has Happened ? > For 3 months a sea of hot mud has been gushing from the ground in > Sidoarjo, East Java, 35 kilometres south of Indonesia's second largest > city, Surabaya. The steaming mud pool is growing at an estimated 50,000 > cubic metres a day, accompanied by hydrogen sulphide gas, and now > reportedly covers more than 25 square kilometres. The flow has not yet > been stopped; thousands of people have lost their homes. > > How bizarre... has this sort of disaster happened before? > > The Sidoarjo disaster is an example of a 'mud volcano'. ________________________________________________________________________ Mud and gas > accumulates when sea sediments are trapped in subduction zones, where one > tectonic plate slides under another, and can erupt out of volcanic cones > or simply from a crack in the ground. Kang Awang. Re- keterangan diatas , bagaimana mengaplikasikan - nya dalam kasus Sidoarjo ? Apakah posisi subduction zone dan saat sedimentasi mendukung pendapat diatas ? Kelihatannya kita harus melihat dan belajar dari kejadian kejadian di - region lain untuk menambah data sebelum suatu kesimpulan final dicapai. Hal ini penting SEKALI karena akan menyangkut suatu keputusan Pengadilan dalam banyak "pengaduan dari masyarakat". Si- Abah ________________________________________________________________________ Mud volcanoes have burst on every > continent, but are abundant in the South Caspian region (offshore and > onshore Azerbaijan) and offshore Indonesia in the East Java Basin. > But the Sidoarjo mud volcano is rather unusual. It's huge. And, says Sam > Rice, a geologist at the University of Cambridge, UK, reports of the mud > eruption suggest that it is a hybrid between typical mud volcanoes and > hydrothermal vents. The mud is of an unusually high temperature (60 °C) > and contains enormously high concentrations of hydrogen sulphide gas. This > suggests that some kind of volcanic, hydrothermal activity is going on at > the same time. > > What creates the conditions for a mud volcano? > > Achim Kopf, a geologist from the University of Bremen, Germany, who has > studied mud volcanoes extensively, explains that marine sediment can be > scraped off an oceanic tectonic plate as it slides underneath a > continental plate. If the sediment accumulates rapidly and water is > trapped in its pores, this can stop the sediment being cemented by > pressure. The resulting reservoir of mud can be trapped underground. In > the case of the East Java mud flow, the mud is thought to have come from a > reservoir some 2.7 kilometres below the Earth's surface. > > And what triggers an eruption? > > A number of things can create a crack that allows trapped mud to bubble to > the surface; particularly earthquakes and drilling. > > And in Java specifically? > > In Java both of these things have happened recently. The oil and gas > exploration company PT Lapindo Brantas is drilling in the area, and the > gas and hot mud first spewed from the company's drilling rig on 28 May. > Geologist Georg Delisle of the Federal Institute for Geosciences and > Natural Resources (BGR), Hannover, Germany, explains that the drilling > apparently penetrated into the liquid sediment and created a connection > back to the surface. The pressure then squeezed up the mud, like > toothpaste from a tube. But it is likely that other connections were made > to the surface, he adds not just through the drilling pipe because > attempts to pump concrete into the pipe to block the flow of mud have > failed. > On 27 May an earthquake struck and devastated Yogyakarta on Java, and this > too could have cracked the ground, potentially helping to release the mud. > But the quake's epicentre was some 300 kilometres away from the mud > volcano (making it only 2 on the Richter scale in that area). > The issue of what, exactly, caused this disaster is highly politically > charged. It is still under investigation by police, the government and > international experts. > > Just how big is the eruption? > > According to many geological experts, the scale of this mud volcano is > unprecedented at least on land. > In 1945, the Makran earthquake in Pakistan triggered the sudden emergence > of three offshore mud volcanoes, and in March 1999 a mud volcano rose out > of the water overnight to form Malan Island, 3 kilometres from Pakistan's > coast. It is hard to estimate the volume of mud created by such underwater > eruptions. And, notes Rice: "Because the extrusion of mud and toxic gas > occurs on the seabed it does not threaten human life and does not make the > headlines." > 'Well-kick' the sudden surface eruption of gas and mud during offshore oil > drilling is common, but usually stops after a few days. Delisle recalls a > smaller-scale incident in the 1960s where a geothermal well in the > Wairakei geothermal field, New Zealand, ran wild: it took 3 months to stop > the geothermal steam that found its way to the surface alongside the > original borehole. > > Can the disaster be stopped? > > Nobody knows. So far, nothing has worked. PT Lapindo Brantas's senior > vice-president Imam Agustino has been quoted saying: "The best-case > scenario [for stopping the mudflow] is now mid-November, but I have to > admit it might never be stopped." > Visit our newsblog to read and post comments about this story. > Article Copyright © 2006 MacMillan Publishers Ltd. > All rights reserved. This material may not be > published, broadcast, rewritten, or redistributed. > > --------------------------------------------------------------------- ----- PIT IAGI ke 35 di Pekanbaru ----- Call For Papers until 26 May 2006 ----- Submit to: [EMAIL PROTECTED] --------------------------------------------------------------------- To unsubscribe, send email to: iagi-net-unsubscribe[at]iagi.or.id To subscribe, send email to: iagi-net-subscribe[at]iagi.or.id Visit IAGI Website: http://iagi.or.id Pembayaran iuran anggota ditujukan ke: Bank Mandiri Cab. Wisma Alia Jakarta No. Rek: 123 0085005314 Atas nama: Ikatan Ahli Geologi Indonesia (IAGI) Bank BCA KCP. Manara Mulia No. Rekening: 255-1088580 A/n: Shinta Damayanti IAGI-net Archive 1: http://www.mail-archive.com/iagi-net%40iagi.or.id/ IAGI-net Archive 2: http://groups.yahoo.com/group/iagi --------------------------------------------------------------------- --------------------------------- Talk is cheap. Use Yahoo! 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