JAKARTA, March 20 (Reuters) - A catastrophic mudflow that has swamped villages on Indonesia's Java island halted briefly for the first time in 10 months, raising hopes that efforts to plug the torrent are working at last, a scientist said on Tuesday. The mud has displaced about 15,000 people following an oil-drilling accident in May in Sidoarjo, an industrial suburb near Surabaya city on the east of Java island, and destroyed toll roads, railways tracks and submerged factories. The 35 minute respite on Monday morning may have been due to the dropping of hundreds of concrete balls into the mouth of what is now known as a mud volcano, said Bagus Endar, a member of a team trying to stop the flow. "There's a possibility that a new equilibrium between the concrete balls and the mud pressure is almost established and the mud has absorbed the energy of the balls," Endar told Reuters. The temperature of the mud has fallen -- another good sign. "It is a positive indication. I'm surprised by this finding," he said. Endar said last week the concrete ball experiment appeared to be working, given a decrease in the mud's daily volume and pressure. Workers were due to drop another 500 chains of concrete balls linked to steel cables on Tuesday, Endar said. Each chain consists of four 20-40 cm (8-16 inch) diameter balls. Anger has been mounting since the disaster, and displaced residents have held several street rallies demanding cash compensation instead of resettlement. PT Lapindo Brantas, the operator of the well where the mud has erupted, had been told by the government to pay 3.8 trillion rupiah ($413 million) to victims and for efforts to halt the flow. But a team set up by the government said the cost would reach around 7.6 trillion rupiah. Lapindo and PT Energi Mega Persada Tbk <ENRG.JK>, which indirectly controls it, dispute whether the mud flow was caused by the drilling and also whether Lapindo alone should shoulder the cost. Energi is owned by the Bakrie Group, controlled by the family of Indonesia's chief social welfare minister, Aburizal Bakrie. ($1 = 9,199 rupiah)
