--> Abstract: The East Java Mud Volcano (2006 to Present): From Earthquake or Drilling Trigger?, by Richard Davies, Maria Brumm, Michael Manga, Richard Swarbrick, Rudi Rubiandini, and Mark Tingay; #90082 (2008)

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The East Java Mud Volcano (2006 to Present): From Earthquake or Drilling Trigger?

Richard Davies1, Maria Brumm2, Michael Manga2, Richard Swarbrick3, Rudi Rubiandini4, and Mark Tingay5
1Durham University, Durham, United Kingdom
2UC Berkeley,, Berkeley, CA
3Geopressure Technology Ltd, Durham, United Kingdom
4Institut Teknologi, Bandung, Indonesia
5School of Earth & Environmental Sciences, Adelaide, SA, Australia

On May 29th 2006 a mud volcano, later to be named ‘Lusi’, started to form in East Java. It is still active and has displaced > 30,000 people. The trigger mechanism for this, the world’s largest and best known active mud volcanoes, is still the subject of debate. Trigger mechanisms considered here are (a) the May 27th 2006 Yogyakarta earthquake, (b) the drilling of the nearby Banjar Panji-1 gas exploration well, and (c) a combination of the earthquake and drilling operations. Based upon theory and a comparison with other earthquakes that have caused eruptions, an earthquake trigger is not expected. But the day before the eruption started (May 28th), while pulling the drill bit and string out of the hole, there was an influx of formation fluid and gas. The monitored pressure after the influx, in the drill string and casing showed variations typical of the leakage of drilling fluid into the surrounding sedimentary rock strata. Furthermore we calculate that the pressure at a depth of 1091 m (the shallowest depth without any protective steel casing) exceeded a critical level after the influx occurred. Fractures formed due to the excess pressure, allowing a fluid-gas-mud mix to flow to the surface. With a very high degree of confidence we can now identify the key factors that caused this man-made disaster.

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