Can Concrete Balls Stop a Volcano's Mud Flow?

In last night's Wall St. Journal a story was told about how a geophysicist in Indonesia is trying to stanch the flow of mud from an erupting volcano---by dropping concrete balls down into the crater. It's a last ditch effort to keep the mud from destroying more houses, and factories and a threatened rail line near the volcano.

Nobody has ever successfully stopped a volcano--this one erupts mud, not molten lava--but since it spews as much as 5.3 million cubic feet of mud a day, and has caused 10,000 people to flee their homes, it is worth trying. The scheme is to drop one thousand 440-pound concrete balls into the crater, using a pulley and crane mounted over the 70-yard wide crater. Will it work?

"Mr Bijaksana acknowledges that 'we're facing something we know very little about,' but says he is more focused on stopping the flow than in determining the cause. "Few people are interested in solving this problem," he says, "Most people are trying to find who's to blame."