As the Lusi mud volcano in Indonesia continues to spew millions of litres of mud every day, debate over the trigger for the eruption is heating up again.
On the day before Lusi was first observed to be erupting in 2006, the oil company Lapindo Brantas was drilling for gas nearby. The well was sealed because the drilling had breached a pocket of saline water. Geologist Richard Davies of Durham University, UK, argues that this prompted the eruption 鈥� a view supported by many petroleum geologists at a meeting in Cape Town, South Africa, last week.
The geologists had been shown figures purportedly showing pressure changes within the borehole in the hours before the eruption, presented by Susila Lusiaga, a drilling engineer who has been working with the Indonesian investigation. According to Davies, who was at the meeting, the figures showed that 鈥渁 huge pressure drop鈥� occurred about an hour and a half after the well was sealed. He says this represents a catastrophic release of saline water through fractures in the surrounding rock, bringing the mud to the surface.
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But Lapindo Brantas contests this interpretation, saying the data presented at the conference was unsourced and unrepresentative. It contends that Lusi鈥檚 eruption was triggered by an earthquake two days earlier 鈥� a view supported by independent geologist Adriano Mazzini of the University of Oslo in Norway.
The company鈥檚 argument lost out in a show of hands after Lusiaga鈥檚 presentation: 42 of the 74 attendees thought the drilling was at fault, three reckoned it was the earthquake, 13 thought both factors contributed and 16 felt the evidence was inconclusive.
