The eruption of the Lusi mud volcano in Indonesia was caused by drilling for oil and gas, a meeting of 74 leading geologists has concluded.
Lusi erupted in May 2006 and continues to spew out boiling mud, displacing around 30,000 people in East Java.
Drilling firm Lapindo Brantas denies a nearby well was the trigger, blaming an earthquake 280km (174 miles) away.
Around 10,000 families who have lost their homes are awaiting compensation, which could run as high as $70m (£43m).
This is the data we wanted to get out - the data I have never been able to show before. It clearly shows that the well failed. It was the driver for the eruption
Professor Richard Davies
Durham University
After debating new evidence at a conference in South Africa, most geologists voted drilling as the cause.
Correspondents describe the result a significant development in the tug-of-war to establish liability for the disaster.