http://discover-indo.tierranet.com/Volcano08.htm
The mud volcanoes.
Mud volcanoes are not extraordinary, they are about a thousand located in several volcanic areas in the world (i.e.: Borders of the Black sea and Caspian sea in Eastern Europe, Azerbaijan, Yellowstone National Park, …). Indonesian islands, which are definitively on one of the most highly active area in the world, are not escaping to this volcanic phenomenon. But there are still some questions on the origin of the event which appeared on May 2006, in the regency of Sidoarjo, on the North East coast of Java, 35 kilometers away from Surabaya, the second largest city of Indonesia. Gas and hot mud started spewing from a well, following the drilling by Lapindo Brantas, an oil well company. Attempts to pump concrete down the well did not stop the flow.