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Sidoarjo Hot volcano Mud
What has happened?
For 3 months a sea of hot mud has been gushing from the ground in Sidoarjo, East Java, 35 kilometres south of Indonesia's second largest city, Surabaya. The steaming mud pool is growing at an estimated 50,000 cubic metres a day, accompanied by hydrogen sulphide gas, and now reportedly covers more than 25 square kilometres. The flow has not yet been stopped; thousands of people have lost their homes. Mr. Win Hendrarso as the regent of Sidoarjo regency take responsibility of social cases at sidoarjo said that PT. Lapindo should take responsibility about the cases. As matter of fact, the regent and vice regent have many problems to claim Lapindo for responsibility.
For 3 months a sea of hot mud has been gushing from the ground in Sidoarjo, East Java, 35 kilometres south of Indonesia's second largest city, Surabaya. The steaming mud pool is growing at an estimated 50,000 cubic metres a day, accompanied by hydrogen sulphide gas, and now reportedly covers more than 25 square kilometres. The flow has not yet been stopped; thousands of people have lost their homes. Mr. Win Hendrarso as the regent of Sidoarjo regency take responsibility of social cases at sidoarjo said that PT. Lapindo should take responsibility about the cases. As matter of fact, the regent and vice regent have many problems to claim Lapindo for responsibility.
Geological setting
The term mud volcano or mud dome is used to refer to formations created by geologically excreted liquids and gases, although there are several different processes which may cause such activity. Temperatures are much cooler than igneous processes. The largest structures are 10 km in diameter and reach 700 metres in height.
About 86% of released gases are methane, with much less carbon dioxide and nitrogen emitted. Ejected materials often are a slurry of fine solids suspended in liquids which may include water (frequently acidic or salty) and hydrocarbon fluids.
Mud volcano systems are common on Earth, including on Java island 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. It forms an inverted extensional basin which has been geologically active since the Paleogene epoch. The basin started to get overpressured during the Oligo-Miocene period. Some of the overpressured mud escapes to the surface forming mud volcanoes, which have been observed at Sangiran Dome and near Purwodadi city (200 km or 124 miles west of Lusi).
The East Java Basin contains a significant amount of oil and gas reserves and therefore the region is known as a major concession area for mineral exploration. The Porong subdistrict, 14km south of Sidoarjo city, is known in the mineral industry as the Brantas Production Sharing Contract (PSC), an area of approximately 7,250 km² which consists of three oil and gas fields: Wunut, Carat and Tanggulangin. As of 2006, three companies — Santos (18%), MedcoEnergi (32%) and PT Lapindo Brantas (50%) — had concession rights for this area; PT Lapindo Brantas acted as an operator.
Mud eruption chronology
The impact of volcano flow
On 28 May 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. The drill string went into a thick clay seam (500–1,300 m deep), and then sands, shells, volcanic debris and into permeable carbonate rocks. At 5:00 a.m. local time (UTC+8), the drill string went deeper to about 2,834 m (9,298 feet), 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 800–100 m northwest of the well, but these stopped on 5 June 2006. During these eruptions, hydrogen sulphide gas was released and local villages observed mud at hot temperature, around 60°C or 140°F.
From a model developed by a geologist, 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 go through the borehole; they penetrated the surrounding overburden pressured strata. The pressure formed some fractures around the borehole to propagate to the surface 200 m away from the well. The most likely cause of these hydraulic fractures in the shallowest strata is by the unprotected drill string with a steel casing. Borehole protection by steel casing has been a common procedure in oil or gas exploration.
Impact
After three months, the unprecedented event had made a river of mud on the surface with a total volume of at least 50,000 m³ with an estimated 7,000–150,000 m³ mudflow erupting every day. By early September 2006, a hot torrential mudflow inundated rice paddies and villages, covering an area of approximately 240 ha and resulting in the displacement of more than 11,000 people from eight villages in the Porong subdistrict. Twenty-five factories had to be abandoned. Rice fields and fish and shrimp ponds have been destroyed, which further threatened Sidoarjo's status as the biggest shrimp producer in Indonesia after Lampung. The Marine Resources and Fisheries Ministry has estimated a financial loss of 10.9 billion rupiahs (US$ 1.2 million) to the fisheries business in Tanggulangin and Porong subdistricts.[10] President Susilo Bambang Yudhoyono declared the 400 ha area inundated by the mud flow as a disaster-prone area unfit for human habitation. As a consequence, 2,983 families had to be relocated to safer places.About 86% of released gases are methane, with much less carbon dioxide and nitrogen emitted. Ejected materials often are a slurry of fine solids suspended in liquids which may include water (frequently acidic or salty) and hydrocarbon fluids.
Mud volcano systems are common on Earth, including on Java island 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. It forms an inverted extensional basin which has been geologically active since the Paleogene epoch. The basin started to get overpressured during the Oligo-Miocene period. Some of the overpressured mud escapes to the surface forming mud volcanoes, which have been observed at Sangiran Dome and near Purwodadi city (200 km or 124 miles west of Lusi).
The East Java Basin contains a significant amount of oil and gas reserves and therefore the region is known as a major concession area for mineral exploration. The Porong subdistrict, 14km south of Sidoarjo city, is known in the mineral industry as the Brantas Production Sharing Contract (PSC), an area of approximately 7,250 km² which consists of three oil and gas fields: Wunut, Carat and Tanggulangin. As of 2006, three companies — Santos (18%), MedcoEnergi (32%) and PT Lapindo Brantas (50%) — had concession rights for this area; PT Lapindo Brantas acted as an operator.
Mud eruption chronology
The impact of volcano flow
On 28 May 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. The drill string went into a thick clay seam (500–1,300 m deep), and then sands, shells, volcanic debris and into permeable carbonate rocks. At 5:00 a.m. local time (UTC+8), the drill string went deeper to about 2,834 m (9,298 feet), 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 800–100 m northwest of the well, but these stopped on 5 June 2006. During these eruptions, hydrogen sulphide gas was released and local villages observed mud at hot temperature, around 60°C or 140°F.
From a model developed by a geologist, 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 go through the borehole; they penetrated the surrounding overburden pressured strata. The pressure formed some fractures around the borehole to propagate to the surface 200 m away from the well. The most likely cause of these hydraulic fractures in the shallowest strata is by the unprotected drill string with a steel casing. Borehole protection by steel casing has been a common procedure in oil or gas exploration.
Impact
On 23 November 2006, eleven fatalities were reported from the explosion of a gas pipe, possibly caused by the mud flow.[12] The accident occurred because the ground subsided 2 m (6.5 feet) due to the significant outflow of mud and water, and a dike collapsed causing the state-owned Pertamina gas pipeline to rupture. The gas sent flames into the sky and according to the local people, they could feel the heat from one kilometer (0.6 miles) away.[13]
As of February 2007, the erupted mud pool had an estimated total volume of 0.012 km³ (12 million liter), covered an area of 360 ha (1.4 miles²), was up to 10 m (32.8 feet) thick, buried four villages and 25 factories, displaced at least 11,000 people and the eruption was still ongoing. It was expected that the mud eruption will last for years to come and the area will experience a significant depression to form a caldera.
Infrastructure has been damaged extensively, including toll roads, railway tracks, power transmission systems, gas pipelines and national artery roads. Speaking in front of the People's Representative Council, the house speaker Agung Laksono declared that the state budget is needed to finance the infrastructure repairs, while PT Lapindo Brantas will be responsible for financing the repairs and also to pay 2.5 trillion rupiah for compensation to the victims. The Porong-Gempol toll road in East Java province has been significantly damaged by the mud flow and was practically inoperable.
The chairman of the national team to handle the disaster, Basuki Hadimuljono, indicated that a 12 km long 120 m wide corridor will be aquired west of the afflicted area to rebuilt the turnpike, and construct a rail line and gas pipe line to restore the disrupted links in the infrastructure. The costs will be carried by the public sector.
Home in the hot volcano mud
How bizarre... has this sort of disaster happened before?
The Sidoarjo disaster is an example of a 'mud volcano'. Mud and gas accumulates when sea sediments are trapped in subduction zones, where one tectonic plate slides under another, and can erupt out of volcanic cones or simply from a crack in the ground. Mud volcanoes have burst on every continent, but are abundant in the South Caspian region (offshore and onshore Azerbaijan) and offshore Indonesia in the East Java Basin.
But the Sidoarjo mud volcano is rather unusual. It's huge. And, says Sam Rice, a geologist at the University of Cambridge, UK, reports of the mud eruption suggest that it is a hybrid between typical mud volcanoes and hydrothermal vents. The mud is of an unusually high temperature (60 °C) and contains enormously high concentrations of hydrogen sulphide gas. This suggests that some kind of volcanic, hydrothermal activity is going on at the same time.
What creates the conditions for a mud volcano?
Building a dike in order to save
Achim Kopf, a geologist from the University of Bremen, Germany, who has studied mud volcanoes extensively, explains that marine sediment can be scraped off an oceanic tectonic plate as it slides underneath a continental plate. If the sediment accumulates rapidly and water is trapped in its pores, this can stop the sediment being cemented by pressure. The resulting reservoir of mud can be trapped underground. In the case of the East Java mud flow, the mud is thought to have come from a reservoir some 2.7 kilometres below the Earth's surface.
And what triggers an eruption?
A number of things can create a crack that allows trapped mud to bubble to the surface; particularly earthquakes and drilling.
And in Java specifically?In Java both of these things have happened recently. The oil and gas exploration company PT Lapindo Brantas is drilling in the area, and the gas and hot mud first spewed from the company's drilling rig on 28 May.
Geologist Georg Delisle of the Federal Institute for Geosciences and Natural Resources (BGR), Hannover, Germany, explains that the drilling apparently penetrated into the liquid sediment and created a connection back to the surface. The pressure then squeezed up the mud, like toothpaste from a tube. But it is likely that other connections were made to the surface, he adds not just through the drilling pipe because attempts to pump concrete into the pipe to block the flow of mud have failed.
On 27 May an earthquake struck and devastated Yogyakarta on Java, and this too could have cracked the ground, potentially helping to release the mud. But the quake's epicentre was some 300 kilometres away from the mud volcano (making it only 2 on the Richter scale in that area).
The issue of what, exactly, caused this disaster is highly politically charged. It is still under investigation by police, the government and international experts.
Just how big is the eruption?
According to many geological experts, the scale of this mud volcano is unprecedented at least on land.
In 1945, the Makran earthquake in Pakistan triggered the sudden emergence of three offshore mud volcanoes, and in March 1999 a mud volcano rose out of the water overnight to form Malan Island, 3 kilometres from Pakistan's coast. It is hard to estimate the volume of mud created by such underwater eruptions. And, notes Rice: "Because the extrusion of mud and toxic gas occurs on the seabed it does not threaten human life and does not make the headlines."
'Well-kick' the sudden surface eruption of gas and mud during offshore oil drilling is common, but usually stops after a few days. Delisle recalls a smaller-scale incident in the 1960s where a geothermal well in the Wairakei geothermal field, New Zealand, ran wild: it took 3 months to stop the geothermal steam that found its way to the surface alongside the original borehole.
Can the disaster be stopped?Nobody knows. So far, nothing has worked. PT Lapindo Brantas's senior vice-president Imam Agustino has been quoted saying: "The best-case scenario [for stopping the mudflow] is now mid-November, but I have to admit it might never be stopped."
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