Mud volcano 'on brink of collapse'

James Randerson, guardian.co.uk, Thursday 29 May 2008 12.46 BST, Article history

Gas emissions from the volcano in East Java (Photograph: Reuters)

The world's largest mud volcano that has been erupting continuously since 2006 is beginning to show signs of "catastrophic collapse", according to geologists who have been monitoring it and the surrounding area.

The volcano - named Lusi - has already devastated homes and businesses in Sidoarjo, East Java, Indonesia, displacing around 10,000 people and killing 14.

Now scientists say that the land near the central vent could sag by up to 146 metres in the next decade. In March, the scientists observed drops of up to 3 metres in one night. Most of the subsidence in the area around the volcano is more gradual, at around 0.1cm per day.

"It is starting to show signs that the central part is undergoing a more catastrophic collapse," said Prof Richard Davies, a geologist at Durham University.

"The fact that the whole area is collapsing means there are probably new faults forming. These faults are new pathways for fluids to seep up to the surface. We've never really seen a mud volcano develop so quickly."

The team have monitored the subsidence using fixed GPS stations which are able to record very accurate ground movements by communicating with satellites. They reported their results in the journal Environmental Geology.

Last year, the Indonesian authorities began a desperate plan to drop 2000 concrete balls into Lusi's central vent in an effort to stem the flow. Davies watched the operation, which went on for 2 months.

"What happened was they dropped them and never saw them again," he said. "It just gobbled them up."

Since it began spewing noxious mud and gasses on May 29 2006, Lusi has blanketed an area of around 7 cubic kilometres, covering 10,426 houses, 35 schools, 65 mosques and one orphanage. The advancing mud is now contained behind human-engineered dykes.

The central collapse may be good news because it will make room for more mud at the surface and so take the pressure off the dykes. But subsidence around the submerged zone will have more impact on the local community.

A bridge that developed cracks has already had to be dismantled, railway tracks have been moved out of line and in November 2006, 13 people were killed in a gas blast caused by an underground pipe rupturing.

Davies does not believe there is any way to stop Lusi now. "I think now the system has become so big ... the plumbing system is so complex you couldn't hope to stop it."