A mud volcano responsible for displacing more than 40,000 people in Indonesia’s East Java province was caused by an oil and gas company owned by one of the country’s richest tycoons, and not by an earthquake as company officials and some scientists have claimed, according to new research out of Australia’s Adelaide University that aspires to finally put to matter to rest.
During the nine years in which the mud volcano, the world’s largest, has erupted continually, it has constituted one of the country’s biggest ongoing controversies and plagued the presidential ambitions of Golkar Party chairman Aburizal Bakrie, whose Bakrie Group controls Lapindo. Lapindo executives have argued that the disaster was caused by natural forces rather than drilling and that the government instead of the company should therefore compensate the victims.
“There has been intense debate over the cause of the mud volcano ever since it erupted,” the study’s lead author, Mark Tingay, said in a statement.
“Some researchers argue that the volcano was man-made and resulted from a drilling accident (a blowout) in a nearby gas well. Others have argued that it was a natural event that was remotely triggered by a large earthquake that occurred 250 kilometers away and two days previously. There has been no scientific consensus about this, and it’s a very hot topic politically in Indonesia.
“Our new research essentially disproves all existing earthquake-triggering models and, in my opinion, puts the matter to rest.”
A satellite image of the mud volcano and the buried city of Sidoarjo in March 2007. The image covers approximately 1200 by 600 meters. Photo: Lapindo Brantas
The study, published in the journal Nature Geoscience, is “the first to use actual physical data collected in the days before and after the earthquake, rather than models and comparisons,” according to the statement.
“The earthquake-trigger theory proposes that seismic shaking induced liquefaction of a clay layer at the disaster location,” Tingay said. “Clay liquefaction is always associated with extensive gas release, and it is this large gas release that has been argued to have helped the mud flow upwards and erupt on the surface. However, we examined precise and continuous subsurface gas measurements from the adjacent well and show that there was no gas release following the earthquake.”
Since the rocks showed no response to the earthquake, Tingay continued, the earthquake could not have caused the disaster.
“Furthermore, the measurements highlight that the onset of underground activity preceding the mud eruption only started when the drilling ‘kick’ occurred, strongly suggesting that the disaster was initiated by a drilling accident,” Tingay said.
“We also use gas signatures from different rocks and the mud eruption itself to ‘fingerprint’ the initial source of erupting fluids,” he added. “We demonstrate that erupting fluids were initially sourced from a deep formation, which is only predicted to occur in the drilling-trigger hypothesis. Taken together, our data strongly supports a man-made trigger.
“We hope this closes the debate on whether an earthquake caused this unique disaster.”
- CITATION: M. R. P. Tingay, M. L. Rudolph, M. Manga, R. J. Davies & Chi-Yuen Wang. Initiation of the Lusi mudflow disaster. Nature Geoscience 8, 493–494 (2015). doi:10.1038/ngeo2472