Fidelis E. Satriastanti, Sidoarjo, East Java – The underground mud volcano that began erupting here since 2006 has permanently changed the landscape of the surrounding area, scientists say.

Richard Davies, a prominent geologist from Britain's Durham University, said on Wednesday that the geological changes that had occurred in Sidoarjo since he last visited four years ago looked set to stay that way.

"I was surprised when we drove up to the middle of the crater where they're actually building stone walls. It suddenly struck me that this is a permanent feature of the Indonesian landscape," he told reporters on the eve of an international scientific symposium hosted by the Humanitus Sidoarjo Fund.

Following Davies' first visit to Sidoarjo in 2007, he published a paper concluding the disaster had almost certainly been caused by gas drilling activities carried out by Lapindo Brantas, which is part-owned by the family business empire of Golkar Party chairman Aburizal Bakrie.

Davies' second paper on the subject predicted the hot mud and gases spewing from the ground would continue for the next 26 years, when it would reach manageable levels. He said the visible decrease in the flow of mud between 2007 and now was a positive sign.

"That's something that scientists are debating, what kind of mechanism is taking place," he said. "Maybe it indicates that it's slowing down and the pressure is diminishing. That's a positive thing to talk about. If the change of eruption style indicates that the pressure has dropped, it's good news."

Mark Tingay, a geophysicist from the University of Adelaide in Australia who has also studied the disaster since it began, said he was similarly surprised by the changes in the landscape caused by the flow of mud. "I came in 2007 and it has changed dramatically since that time," he said.

"The eruption seemed to have slowed down dramatically as we walked down the crater. But what struck me was that all of those villages and those houses were completely gone."

Pitando Hariyadi, a field officer from the Sidoarjo Mudflow Mitigation Agency (BPLS), confirmed that the mudflow seemed to have peaked.

"We've gotten used to the eruption, but it's slowing down," he said. "Yesterday, the mud stopped gushing for 13 minutes, which is a record. Normally we get gushers every 20 seconds."

Throughout 2009, the mud flowed out of the ground at an average rate of 100,000 cubic meters a day, according to BPLS data. This year, the daily average has dropped to 13,000 cubic meters.

Pitando also said that the mud had indeed created a new landscape in the area and that would likely stay that way. He said the initial mudflow had moved in only one direction, but later spread out in all four directions, including toward the Porong highway.

"The mud pushed through the dam built to contain it," he said. "That dam was actually built only six months ago. We're now standing over part of the dam that got submerged by the flow."

The mudflow has destroyed hundreds of homes, swamped 720 hectares of land and displaced more than 11,000 people since it began erupting in late May 2006.