Indonesia disaster shows risks of mud volcanoes

Indonesia disaster shows risks of mud volcanoes
Fri Oct 20, 2006 10:49am ET
By Alister Doyle, Environment Correspondent

OSLO (Reuters) - In a village in Indonesia's East Java province, a man is struggling to watch television with a volcano erupting in his living room.

Risks from volcanoes that ooze mud rather than spew lava have long been underestimated worldwide, even with a cataclysmic mudflow in another part of Java that has swamped an area the size of Monaco and forced 10,000 people from their homes.

Experts say the disaster, flooding the Sidoarjo region since May 29, highlights lack of knowledge about mud volcanoes, thousands of which have been found from Alaska to Australia. They range from tiny seeps to cones 500 meters (1,640 ft) tall.

"In Java nobody ever studied mud volcanoes," said Adriano Mazzini, a leading Italian volcano expert at the University of Oslo who says the Indonesian disaster may signal the first time people have recorded the birth of a mud volcano.

"In Indonesia they have other priorities -- magmatic volcanoes, earthquakes, tsunamis," he told Reuters.

On Java, villages about 10-20 km (6-12 miles) north of the mud eruption -- Gununganyar, Kalanganyar and Pulungan -- are built on old, near-dormant mud volcanoes that must have seemed attractive-looking mounds to village founders.

Pulungan was the most vivid example of ignoring the risks of mud volcanoes, such as subsidence.

"We went to one house where a man took us into his living room. He opened the cupboard beneath the television, and there were seeps erupting," Mazzini said after a recent trip. Continued...

Another home in Pulungan has collapsed and elsewhere many residents are worried by seeps of gas, mud and fluids. The volcano may have been stirred by an earthquake on May 27, two days before the catastrophic mudflow began.

BUILDING LIFTED
In Kalanganyar, the end of one long thin building had been lifted a meter or two over the years by the pressures from a mud volcano bulging beneath. "Mud volcanoes need better study," said Antje Boetius, a professor at the International University of Bremen in Germany.

She noted that they could cause disasters, ranging from subsidence to tsunamis. "They mean something for humans -- it's not just scientific curiosity," she said. Mud volcanoes are often caused by a build-up of pressure from sediments crushed several kilometers below the surface that release methane and other gases. They are often found near oil and gas deposits, also caused by a crush of organic matter.

As in Java, they can also happen near where tectonic plates of the earth's crust rub together. Mazzini said it was impossible to say how long the Sidoarjo flow would last. He said researchers would "probably never know" exactly what triggered the catastrophic mudflow at Sidoarjo, releasing the build-up of pressure deep below ground. The trigger might have been a magnitude 4 earthquake two days before the mudflow began, he said, or the drilling of a gas exploration well operated by PT Lapindo Brantas Inc, which is controlled by Pt Energi Mega Persada.
Mud volcanoes are rarely deadly since they more often seep rather than explode. In 1997, an eruption of a mud volcano at Piparo, a farming village in central Trinidad, threw mud 45 meters (150 ft) into the air, covering many homes. No one died.

In Azerbaijan, a large mud volcano that erupted in 2001 also released giant flares of methane.

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