Four experts put forward varying hypotheses, including the university’s professor of geology, Richard Davies, it said in a press release.
Forty-two scientists voted in favour of Davies’ argument that the cause lay with a gas exploration well, Banjar-Panji-1, that was being drilled in the area by oil and gas company Lapindo Brantas, it said.
Lapindo Brantas disputes this, and says the blame lies with an earthquake two days earlier in Yogyakarta, 280 kilometres (175 miles) away.
Three scientists agreed with this explanation.
Sixteen said the evidence was inconclusive, while 13 believed that a combination of quake and drilling was to blame, the university said.
The vote was taken at a meeting that took place during a conference of the American Association of Petroleum Geologists, which ran from October 26-29.
Davies has led several investigations into Lusi and contends that the quake was too small and too distant to have caused the blowout, whereas the gas well was being drilled only 150 metres (yards) from the volcano site.
At the Cape Town meeting, he put forward new data that he said proved that the day before the eruption, the well took a huge
influx of fluid, resulting in intolerable pressures.
The data “provide a compelling tape recording of the well as it started to leak,” said Davies.
“I remain convinced that drilling was the cause of the mud volcano. The opinion of the international scientists at the event in South Africa adds further weight to my conviction and the conclusions of many other leading scientists who have studied Lusi.”
Davies says Lusi is collapsing by about 13 metres (42 feet) a year and could eventually subside to more than 140m (455 feet), inflicting lasting environmental damage.