HR: 1340h
AN: V13B-1341    [Abstracts]
TI: Triggering and dynamic evolution of the LUSI mud volcano, Indonesia
AU: Svensen, H
EM: henrik.svensen@fys.uio.no
AF: Physics of Geological Processes, University of Oslo, Box 1048, Oslo, 0316, Norway
AU: * Mazzini, A
EM: adriano.mazzini@fys.uio.no
AF: Physics of Geological Processes, University of Oslo, Box 1048, Oslo, 0316, Norway
AU: Akhmanov, G G
AF: Moscow State University, Faculty of Geology, Vorobjevy Gory, Moscow, 119992, Russian Federation
AU: Aloisi, G
AF: Laboratoire de Paléoenvironnements et Paléobiosphère, Université Claude-Bernard, UMR 5125 CNRS, 2, rue Dubois, Villeurbanne cedex, 69622, France
AU: Planke, S
EM: planke@vbpr.no
AF: Physics of Geological Processes, University of Oslo, Box 1048, Oslo, 0316, Norway
AU: Planke, S
EM: planke@vbpr.no
AF: VBPR, Oslo Research Park, Oslo, 0349, Norway
AU: Sørenssen, A
EM: anders.malthe-sorenssen@fys.uio.no
AF: Physics of Geological Processes, University of Oslo, Box 1048, Oslo, 0316, Norway
AU: Istadi, B
AF: EMP Brantas, Lapindo Brantas Inc., JI. Jend. Gatot Subroto 42, Jakarta, 12710, Indonesia
AB: Mud volcanoes are geologically important manifestations of vertical fluid flow and mud eruption in sedimentary basins worldwide. Their formation is predominantly ascribed to release of overpressure from clay- and organic- rich sediments, leading to impressive buildup of mud mountains in submarine and subaerial settings. Here we report data from two fieldworks on a newly born mud volcano named LUSI eruption in Eastern Java (Indonesia). The eruption site appears close to an active magmatic complex in a backarc sedimentary basin in Indonesia. Its specific location results in a high background temperature gradient that triggers mineralogical transformations and geochemical reactions at shallow depth. The eruption of 100 deg.C mud and gas that started the 29th of May 2006 flooded a large area within the Sidoarjo village in Northeast Java. Thousands of people have so far been evacuated and, since the initial eruption, the flow rate escalated from 5000 to 120,000 m3/d during the first eleven weeks. Then the erupted volume started to pulsate between almost zero and 120,000 m3/d in the period August-September, whereas it increased dramatically following swarms of earthquakes in September, before reaching almost 180,000 m3/d in December 2006. Fifteen months after the initial burst, LUSI is still vigorously erupting up to 111,000 m3/d, the average subsidence of the area reached 11 m. Seismic images show that a pre-existing structure was present before the eruption. Based on geochemical and field results, we propose a mechanism where the eruptions started following the 27th of May earthquake due to fracturing and accompanied depressurization of >100 deg.C pore fluids from > 1700 m depth released from a structure in already critical conditions. This resulted in the formation of a quasi-hydrothermal system with a geyser-like surface expression and with an activity influenced by the regional seismicity.
UR: http://folk.uio.no/adrianom/
DE: 8434 Magma migration and fragmentation
SC: Volcanology, Geochemistry, Petrology [V]
MN: 2007 Fall Meeting