Lapindo Mud… 2006 – Present day..

The Sidoarjo mud flow or Lapindo mud, also informally abbreviated as Lusi, a contraction of Lumpur Sidoarjo (lumpur is the indonesian word for mud), is a since May 2006 ongoing eruption of gas and mud in the subdistrict of Porong, Sidoarjo, East Java – Indonesia (about 20 kilometers south of surabaya). It is considered to be a mud volcano. It appears that the flow will continue indefinitely and so far all efforts to stem the flow have failed.

Mud volcano systems are fairly common on Earth, and particularly in East Java province. Beneath the island of Java is a half-graben lying in the east-west direction, filled with overpressured marine carbonates and marine muds.[2] It forms an inverted extensional basin which has been geologically active since the Paleogene epoch.[3] The basin started to become overpressured during the OligoMiocene period. Some of the overpressured mud escapes to the surface to form mud volcanoes, which have been observed at Sangiran Dome and near Purwodadi city (200 km or 124 miles (200 km) west of Lusi).

BACK TO MAY… 1st Eruption….

On May 28, 2006, PT Lapindo Brantas targeted gas in the Kujung Formation carbonates in the Brantas PSC area by drilling a borehole named the ‘Banjar-Panji 1 exploration well’. In the first stage of drilling the drill string first went through a thick clay seam (500–1,300 m deep), then sands, shells, volcanic debris and finally into permeable carbonate rocks.[1] at this stage the borehole was surrounded by a steel casing to help stabilise it. At 5:00 a.m. local time (UTC+8) a second stage of drilling began and the drill string went deeper, to about 2,834 m (9,298 ft), this time without a protective casing, after which water, steam and a small amount of gas erupted at a location about 200 m southwest of the well. Two further eruptions occurred on the second and the third of June about 800–1000 m northwest of the well, but these stopped on June 5, 2006. During these eruptions, hydrogen sulphide gas was released and local villagers observed hot mud, thought to be at a temperature of around 60 °C (140 °F).

From a model developed by geologists working in the UK, the drilling pipe penetrated the overpressured limestone, causing entrainment of mud by water. The influx of water to the well bore caused a hydrofracture, but the steam and water did not enter the borehole; they penetrated the surrounding overburden and pressured strata. The extra pressure formed fractures around the borehole that propagated 1-2km to the surface and emerged 200 m away from the well. The most likely cause of these hydraulic fractures was the unprotected drill string in the second stage of drilling. Borehole protection by steel casing is a common procedure in oil or gas exploration.

Present Time ….

As of September 2, 2008, the mud flow is still ongoing. A study has found that the mud volcano is collapsing under its own weight, possibly beginning of caldera formation.[36]. The researchers say the subsidence data could help determine how much of the local area will be affected by Lusi. Their research used GPS and satellite data recorded between June 2006 and September 2007 that showed the area affected by Lusi had subsided by between 0.5 meters [1.6 feet] and 14.5 meters [47.6 feet] per year. The scientists found that if Lusi continued to erupt for three to 10 years at the constant rates measured during 2007 then the central part of the volcano could subside by between 44 meters [144 feet] and 146 meters [479 feet] – 26 meters [85 feet] longer than a football pitch. They propose the subsidence is due to the weight of mud and collapse of rock strata due to the excavation of mud from beneath the surface. Their study has also found that while some parts of Sidoarjo are subsiding others are rising suggesting that the Watukosek fault system has been reactivated due to the eruption. [37]

Workers helping to relocate families after new hot gas flows began to appear. The workers were taken to a local hospital to undergo treatment for severe burns. In Siring Barat, 319 more families have been displaced and in Kelurahan Jatirejo, 262 new families are also going to be affected by the new flows of gas. Protesting families took to the streets demanding compensations, which in turn added more delays to the already stressed detour road for Jalan Raya Porong and the The Porong-Gempol toll road.

The government has stated that their heart is with the people. Though the cabinet meeting on how to disperse the compensation has been delayed until further notice. Local official, Saiful Ilah, signed a statement announcing that “The government is going to defend the people of Siring.” After this announcement all protests came to an end and traffic flow returned to normal an hour later.

taken from : Wikipedia

~ by sidoarjosaiki on October 23, 2008.

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