FOR the past four months, a steady flow of hot and noxious mud has erupted from the earth, swamping villages, factories and rice paddies near Indonesia's second-largest city, Surabaya. Four villages, 20 factories and about 435 hectares (1,075 acres) of farmland have so far been submerged and 13,000 people have been evacuated from the area. Despite the hasty construction of a network of earthen dykes, in an effort to contain the muddy seepage, 12 more villages are in pressing danger of being swamped. A team of European scientists which visited the scene last month said the mud-flow could continue for decades—and may be impossible to stop.

A seismically-active archipelago, Indonesia is used to geological crises. But the mud-flow is also causing political tremors. It erupted 150 metres from where a gas company called PT Lapindo Brantas was drilling a 3km exploratory well. The company is controlled by the family of Indonesia's powerful chief welfare minister, Aburizal Bakrie. It has not accepted that it was responsible for the eruption, and it is by no means clear that it was. But some experts have alleged that the company was using unsafe drilling methods, including failing to encase properly the exploratory shaft, and that this could have contributed to the disaster. Another company involved in the drilling, PT Medco Energy, has accused a drilling subcontractor called Federated International (2000)—one of whose directors is a nephew of Mr Bakrie—of “gross negligence”. A criminal investigation into the causes of the disaster has made slow progress. This is a bit surprising, since nine employees of the drilling firm and of Lapindo have been declared official suspects.

Despite its denial of responsibility, Lapindo has so far spent more than $75m on compensation, containment and clean-up costs arising from the mud-slick. It is trying to staunch it by pumping concrete into the breach, and by drilling four new shafts. But it probably stands little prospect of success. Adriano Mazzini, a geologist from Oslo University who was among the European team of experts, said it could take “one, ten or 100 years” for the underground pressure that is causing the eruption to be released. Until then, he says, “It will be very, very difficult” to stop it.

The final costs of the disaster could run to hundreds of millions of dollars. The mud-flow is accelerating; it is currently at over 125,000 cubic metres a day—enough to cover a football pitch in about 15 metres of muck.

Sensing that the crisis was getting out of hand, Indonesia's central government took over managing it last month, but ordered Lapindo to continue paying for the operation. The government has decided to try to divert the mud into the sea, 15km away, through a local river. Environmentalists say that this threatens to cause a second disaster, because the untreated sludge will do dreadful damage to sea life, and thereby also harm the livelihoods of millions of people living on Java's eastern coast.

Meanwhile, to the fury of those who suspect the alleged wrong-doers might not be held to account, the government is expected to announce that it will pay for the crisis-management operation if Lapindo's owners go bankrupt because of it. Indonesia's taxpayers would then be left with a massive bill for a mess that they played no part in creating.