News

New evidence links exploration well and Lusi mud volcano

(12 February 2010)

Lusi mud volcano (courtesy Channel 9 Australia)

New data provides the strongest evidence yet that the world’s biggest mud volcano was not caused by an earthquake, according to scientists led by Durham University.

The Lusi mud volcano has killed 13 people and displaced thirty thousand others in East Java, Indonesia.

Drilling firm Lapindo Brantas has denied that a nearby gas exploration well was the trigger for the volcano, blaming an earthquake 280km (174 miles) away. They have backed up their claims in an article led by Nurrochmat Sawolo senior drilling adviser for Lapindo Brantas published in the journal: Marine and Petroleum Geology.

In response, a group of scientists from the UK, USA, Australia and Indonesia, led by Prof Richard Davies from Durham University have written a discussion paper in which they refute the main arguments made by Nurrochmat Sawolo and document new data that provides the strongest evidence to date of a link between the well and the volcano.

Prof Davies said: "The disaster was caused by pulling the drill string and drill bit out of the hole while the hole was unstable. This triggered a very large ‘kick’ in the well where there is a large influx of water and gas from surrounding rock formations that could not be controlled.

"We found that one of the on-site daily drilling reports states that Lapindo Brantas pumped heavy drilling mud into the well to try to stop the mud volcano. This was partially successful and the eruption of the mud volcano slowed down. The fact that the eruption slowed provides the first conclusive evidence that the bore hole was connected to the volcano at the time of eruption."

The Durham University-led group of scientists believe that this puts the issue beyond all reasonable doubt. Their discussion paper said: ‘The pumping of heavy mud caused a reduction in the rate of flow to the surface. The reason for pumping the mud was to stop the flow by increasing the pressure exerted by the mud column in the well and slowing the rate of flux of fluid from surrounding formations.’

Arguments over the causes of the Lusi volcano have stalled the establishment of liability for the disaster and delayed compensation to thousands of people affected by the mud. The Yogyakarta earthquake that occurred at the time of the volcano was cited by some as a possible cause of the eruption but the Davies-led science team has rejected this.

Co-author of the discussion paper, Prof Michael Manga, of University of California, Berkeley said:

"An earthquake trigger can be ruled out because the earthquake was too small given its distance and the stresses produced by the earthquake were minute - smaller than those created by tides and weather.