Indonesia tries to stem flow from mud volcano with hundreds of concrete balls

PORONG, Indonesia -- For nine months, a gaping hole in the ground has spit out a biblical torrent of hot, black mud, swallowing thousands of homes outside Indonesia's second-largest city and attracting geologists from around the world.

Most say the flow is unstoppable, but Indonesian experts refuse to listen, and they have recently began carrying out a scheme straight from a Hollywood movie: dropping nearly 1,500 concrete balls into the mouth of the mud volcano.

"We know lots of people think this is a crazy idea," said professor Satria Bijaksana, one of three geologists behind the $130 million plan aimed at reducing the spew of the sludge by as much as 70 percent. "But we think it will work."

Mud volcanos are fairly common along volatile tectonic belts and in areas rich in oil and natural gas like Indonesia.

But the eruption just outside the city of Surabaya is exceptional because of the sheer volume of mud that has been surging each day from the hole -- enough to fill 50 Olympic-sized swimming pools. Twelve villages and 20 factories have been swallowed, with mud-caked roofs and the tops of lamp posts as the only reminders of what once was there.

Some scientists suggest the rupture was triggered by improper drilling at a nearby natural gas site. Other research points to a major earthquake two days before the mud first appeared in a rice field in May 2006.

The ball-dropping operation, which began last month, follows several failed attempts to contain or stop the mud.

Engineers tried building earthen dams to hold back the sludge, but they are about to overflow. The viscosity of the mud hindered efforts to channel it into the sea. A plan to cap the volcano with concrete was abandoned almost immediately as ill-conceived.

Now, engineers are using a pulley system to hoist the beachball-sized concrete spheres over the crater before dropping them from a height of around two stories. The balls, each weighing about 150 pounds, are chained together in clusters of four.

So far, nearly 150 have been tossed into the abyss, too few to make a real impact. The government has given them another five weeks to make a difference, or walk away and let the volcano run its course.

Critics say almost everything depends on the shape of the mammoth gullet, believed by the ball-dropping team to resemble a champagne glass, although recent sonar readings indicate its base may be larger than initially thought.

"The hope is that the balls will fit snugly at the bottom, but it is unlikely to be that simple," said Richard Davies, a geologist at Durham University in Britain who has studied the mud volcano, noting that there apparently are several separate vents.

"When they drop these balls in, it could be that they just drop straight down, they could drop hundreds of meters and just fill a large void."

Another concern is that if the hole is effectively blocked, pressure will build up behind the balls and trigger eruptions elsewhere.

"It's like putting your thumb at the end a hose pipe -- a fairly rotten hose which could spring a leak anywhere along its length," said Davies. "The fluid will take the next easiest path ... if it's a really solid plug, then the pressure would go elsewhere and possibly reactivate other fractures."

But with scientists predicting the mud could flow for decades or even centuries, those who have been made homeless say it's worth a shot. Already, 2 square miles of land has been submerged, and a key rail line and highway are now being threatened.

The displaced residents are living in a former market near the site.

"They can't just give up, they have to fight this mud," said Subagio, a 49-year-old father of four. "We have no home, no job, nothing. And who knows how long we will be able to stay here?"

Much of his anger is directed at PT Lapindo Brantas, the Indonesian gas company accused of triggering the eruption by creating fissures in a bed of porous limestone during faulty drilling. The company denies it is to blame, but it is under investigation.

The government estimates the eruption will cause $844 million in damage and has ordered Lapindo, which is funding the concrete-ball experiment, to pay half that. Some of the money will go to compensate victims.

The disaster zone has been turned into a stopping point for some tourists, who pay about 10 cents to young, unemployed men for a glimpse. Dodik Prastia, who worked in a watch factory before it was swallowed up by the mud, sells anti-Lapindo DVDs to visitors.

"It's appalling, I don't know what to say," said Bobbe Wood, from Vancouver, British Columbia, as her eyes skim over the massive black lake, balls being dropped in the distance.

"Let's hope this project works, because if it doesn't, well what then? The road, the railway, everything will be washed away," she said.