Sidoarjo mudflow or Lusi [Lumpur Sidoarjo, Bahasa Indonesia, = Sidoarjo mud], mud volcano, Sidoarjo regency, central East Java prov., Indonesia, 20 mi (30 km) S of Surabaya. In May, 2006, a hot mudflow erupted close to a drill site in the Porong district of Sidoarjo, eventually creating a mud volcano that has since buried a dozen villages in the surrounding area and displaced more than 40,000 people. At its height, some 235,000 cu yd (180,000 cu m) of mud were disgorged every day. The oil exploration company blamed the mudflow on a strong earthquake that struck the day before near Yogyarkata some 180 mi (300 km) away, but many geologists believe that eruption was due entirely or largely to side-effects of the drilling, which hit a pressurized aquifer and was not using a protective casing at the time of the eruption. Attempts to block the mud volcano's mouth proved a failure. Some of the mud has been directed to the sea using the nearby Porong River, but most of it has been contained with enormous levees. The disgorging of the mud from beneath the site and the weight of the mud on the surface is causing the site to subside; it has been estimated that the eruption could continue for 30 years and the area around the volcano's mouth could subside as much as 460 ft (140 m).
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