Indonesia's mud volcano 'unnatural disaster'

The erupting mud volcano in Sidoarjo, which is located about 30 km south of Surabaya
in East Java, Indonesia has been producing large quantities of hot water and mud.

Paris (AFP/iol.co.za) -- Scientists on Monday delivered a rebuttal to claims that an earthquake, and not drilling for gas, unleashed a "mud volcano" that has been spewing sludge in Indonesia for the past two years.

"We are more certain than ever that the Lusi mud volcano is an unnatural disaster and was triggered by the drilling of the Banjar-Panji-1 well," said British professor Richard Davies.

The volcano in Sidoarjo district of East Java has been spewing the equivalent volume of scores of Olympic-sized swimming pools of mud a day since erupting to life on May 29, 2006.

The drilling was carried out by oil and gas company Lapindo Brantas, owned by the family of wealthy welfare minister Aburizal Bakrie.

In January 2007, Davies, of Durham University in northeastern England, argued that the drilling was most likely to blame, an accusation refuted by Lapindo, which pointed the finger at an earthquake two days earlier in the city of Yogyakarta 250 kilometres away.

The new study, published in the peer-assessed academic journal Earth Planetary Science and Letters, outlines and analyses a detailed record of operational incidents in the drilling of Banjar-Panji-1.

Lapindo "has confirmed that the data is correct," Durham University said in a press release. The lead author of the study is Davies, and includes British, Indonesian and Australian investigators.

The authors said they were "99 percent" certain that the Yogyakarta quake could not have caused the mud volcano to start up, as any underground pressure it exerted could only have been tiny.

"We have known for hundreds of years that earthquakes can trigger eruptions. In this case, the earthquake was simply too small and too far away," the university quoted co-author Michael Manga, a professor of University of California at Berkeley, as saying.

Davies added: "We show that the day before the mud volcano started there was a huge kick' in the well, which is an influx of fluid and gas into the wellbore. We show that after the kick the pressure in the well went beyond a critical level."

"This resulted in the leakage of the fluid from the well and the rock formations to the surface - a so called underground blowout'. This fluid picked up mud during its ascent and Lusi was born."

If there had been more protective casing in the borehole, the drillers would have had more chances of controlling this pressure, he said.

Lusi is still flowing at 100 000 cubic metres per day - enough to fill 53 Olympic-sized swimming pools, the researchers added.

In separate research published in May, Davies said that Lusi was collapsing under its own weight as so much mud had been excavated from underneath.

Twelve villages have been affected by the spreading mud and at least 36 000 people have been forced to flee their homes.