Drilling of a gas exploration well – not an earthquake – caused the eruption of a mud volcano on the Indonesian island of Java, a team of international scientists has concluded.
The volcano, dubbed Lusi, has been spewing hot, foul-smelling mud for two years and has forced more than 50,000 people to flee their homes.
"All of the evidence points to a drilling induced origin for this disaster," Mark Tingay, an Australian geologist and member of the team of experts, told Al Jazeera on Tuesday.
He said the gas exploration firm, PT Lapindo Brantas, had been "drilling with very narrow safety margins" at the site of the eruption.
|Efforts to stem the mudflow |
have all failed [EPA]
Two years on from when the eruption first began, Tingay said there was little hope that any human intervention would bring it to an end.
"The time to stop this event has long passed," he said. "This is now a phenomenon that will keep going until it naturally dies out."
In a joint statement the team of American, Indonesian and Australian scientists who have been studying the volcano said they were "more certain than ever" that the eruption was "an unnatural disaster".
The scientists' findings have been published in the journal Earth and Planetary Science Letters.
"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," British professor Richard Davies was quoted as saying.
"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."
In addition to the evacuations, Lusi has caused damage that the Indonesian government estimates could reach $5bn.
More than 15,000 people displaced
Mud 20 metres deep in some places
Mud enough to fill about 60 Olympic swimming pools gushes out daily
Government estimates losses could reach $5bn
The mud now covers about 6.5 sq km and continues to flow at a rate of 100,000 cubic metres, or 60 Olympic-size swimming pools, a day.
Various methods have been tried to stop the flow, including dropping large concrete balls into the mouth of the volcano, but with no effect.
The mining company, PT Lapindo Brantas, had argued that the May 2006 eruption was triggered by a 6.3 magnitude earthquake that caused widespread damage in and around the city of Yogyakarta two days before the eruption.
But scientists involved in the latest study said the quake was too far away and the change in underground pressure it caused would not have been enough to cause the volcano.
Indonesia's government has ordered Lapindo to pay $406m in compensation to the victims of the volcano and to cover the damage caused by the eruption.