Mud volcano set to erupt for quarter-century - scientists
Paris (AFP) Feb 24, 2011
A mud volcano that has displaced more than 13,000 Indonesian families will erupt for at least a quarter of century, emitting belches of flammable gas through a deepening lake of sludge, scientists reported on Thursday.
Underground pressure means the volcano "Lusi," in Sidoarjo, East Java, is likely to gush grey mud until 2037, when volumes will become negligible, according to their computer model.
But gas will continue to percolate through it for decades and possibly centuries to come.
"Our estimate is that it will take 26 years for the eruption to drop to a manageable level and for Lusi to turn into a slow bubbling volcano," said team leader Richard Davies, a professor of Earth sciences at Durham University, in northeast England.
Thirteen people were killed after Lusi erupted on May 29 2006.
At its height, the volcano gushed 40 Olympic-sized pools of mud each day, a rate that has now slowed to four per day, Davies said by phone.
Its lake of mud has now smothered 12 villages to a depth of up to 15 metres (nearly 50 feet) and forced around 42,000 people from their homes.
The computer simulation is based on data from two existing commercial gas wells in the same region and on seismic reflection data that gives a picture of Lusi's geological structure.
"In the middle of the lake, or the volcano, is a vent that is 50 metres (164 feet) wide but there are 166 other vents that have popped up over the last four-plus years," said Davies.
"These have popped up in factories, in roads, in people's houses. Some of them have ignited, there have been examples of people being hurt by flames that have been formed due to the ignition."
Lusi's staying power means it will be a long-term but gradually less dramatic menace, he warned.
"You can't return to the area. In fact, ultimately, probably the impact of the volcano will increase," Davies declared.
"I think we've seen the most dramatic destruction. But it's not the end of the story. These vents are still forming."
The area is also slowly subsiding, and by 2037 could have formed a depression 95-475 metres (312-1558 feet) deep.
The Indonesian government blames the eruption on an earthquake that struck days before, about 280 kilometres (174 miles) away from Lusi.
But foreign experts accuse a gas drilling company, Lapindo Brantas, of failing to place a protective casing around a section of its well.
As a result, the well hole was exposed to a "kick" from pressurised water and gas that lie beneath the layer of mud, thus driving the grey, concrete-like fluid to the surface.
The study is released in the London-based Journal of the Geological Society.
earlier related report
Bulusan volcano spewed a huge ash column on Monday, sending thousands of people fleeing their homes. More than 700 remained at evacuation centres Wednesday awaiting advice on when it is safe to return, aid officials said.
The National Disaster Risk Reduction and Management Council said it handed out some 6,000 dust masks to residents of Irosin, one of three towns affected by the ashfall, including nearly 500 people at an evacuation centre there.
The health ministry meanwhile distributed face masks in the nearby town of Bulan, where a two-year-old boy died from an asthma attack aggravated by ashfalls caused by the eruption, it said in a statement.
Government doctors are checking the medical condition of people in affected areas, it added.
Volcanic ash can cause nose, throat, eye and skin irritation as well as contaminate tap water, while prolonged exposure can cause lung disease, according to the health ministry.
Government volcanologists said they had recorded one volcanic quake in the 1,559-metre (5,115-foot) volcano in the past 24 hours, but thick clouds hampered visual observations of further steam and ash emissions.
The government said human activity has been banned within four kilometres (2.5 miles) of its crater as a precaution.
Bulusan is among 23 active volcanoes in the Philippines, which is located in the so-called Ring of Fire of volcanic activity around the Pacific.
Bulusan, 360 kilometres southeast of Manila, last erupted between March and June of 2006.
The volcano also shot ash into the air in November last year, forcing hundreds of people to evacuate their homes.
However volcanologists said this was not an eruption, but heated ash deposits near the crater mouth that exploded and burst out on contact with rainwater.
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Manila (AFP) Feb 23, 2011
Philippine health authorities handed out face masks to thousands of residents around an erupting volcano on Wednesday after a child died of an asthma attack blamed on falling ash, officials said. Bulusan volcano spewed a huge ash column on Monday, sending thousands of people fleeing their homes. More than 700 remained at evacuation centres Wednesday awaiting advice on when it is safe to retu ... read more
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