29, May 2006 : Birth of the mud volcano of Sidoarjo

Five years ago, at 5 o'clock in the morning of May 29, the inhabitants of the village of Sidoarjo in East Java witnessed the beginning of the eruption of a mud volcano - and still today every day nearly 30.000 cubic metre of gasses, water and mud emerge from the underground.

Already in 1778 the Italian physicist Alessandro Volta examined the methane gas outpouring from the mud volcanoes of Pietramala near Florence, from time to time this gas ignited producing up to 2 meter high natural torches.
The German explorer Alexander von Humboldt described mud volcanoes he encountered near the Columbian village of Turbaco during his expedition to South America in the years 1799 to 1804 - even if he exaggerated the height with three to four meters (the mounds are approximately one meter high).

Fig.1. The mud volcanoes near the Columbian city of Turbaco, after HUMBOLDT & BONPLAND (1804): Personal Narrative of Travels to the Equinoctial Regions of America, During the Years 1799-1804.

Today worldwide more than 1.100 mud volcanoes are recognized, located on continental shelves but also on continents.
There are various mechanisms that can cause the eruption of mud from the underground, whereby only the last two are regarded as true mud volcanoes, the rest as mud pots.

- Through magmatic activity heated gas or groundwater, that circulating carries with it loose or reworked sediments

- Liquefaction effects during an earthquake.

- Overpressured groundwater, fluids, gas and sediments in sedimentary basins, like a cap impermeable rocks can prevent underlying sediments to escape, as soon as this cap is damaged or removed water begins to rise to the surface.

- Cold methane gas or other fluids escaping from the underground and transporting sediments.

However the mud volcano of Lumpur Sidoarjo ("mud of Sidoarjo"), abbreviated to Lusi, is unique as probably the only artificial mud volcano in history. It erupted up to 180.000 cubic metres mud per day but until 2011 this amount decreased to 30.000 cubic metres per day, however only the construction of dams limited the extant of the mud flow to 7 square kilometres in 2008 - 30.000 people had to be evacuated and 11 people were killed in the explosion of a submerged gas-pipeline.



The cause of the Lumpur Sidoarjo is still controversial. In March 2006 the Indonesian oil company Lapindo Bantas started a drilling campaign 200 meter distant to the future eruption site. The company denies a direct connection to the drill operations and the eruption and affirms that an earthquake and reactivation of an underground fault system triggered the flow of overpressured gases and groundwater from a reservoir in carbonate rocks into the overlying clays.
Some independent research (DAVIES et al. 2007) blames the company to have not adequately coated the borehole. It collapsed in a depth of 1.100 meters after encountering the carbonate reservoir, the growing pressure crashed the surrounding impermeable clay rocks, therefore enabling gas and water to reach the surface and feed the mud volcano.

Fig.2. Schematic three-dimensional model of the Lusi mud volcano according to DAVIES et al. 2007, the research team proposed that an inadequate coating of the bore hole caused fractures in the surrounding rocks, causing overpressured fluids to push to the surface. A legal investigation concluded however that the drill operations were carried out according to standard procedure, the charge of negligence by oil company Lapindo Bantas was therefore rejected.
According to the spokesman the company states that the drill operations were carried out according to standard procedure, the legal case and especially the payments of compensation proceed very slowly and since 2010 legal actions against the company have stalled.

Bibliography:

DAVIES, R.J.; SWARBRICK, R.E.; EVANS, R.J. & HUUSE, M. (2007): Birth of a mud volcano: East Java, 29 May 2006. GSA Today Vol. 17(2): 4-9
HUMBOLDT, von A. & BONPLAND, A. (1804): Personal Narrative of Travels to the Equinoctial Regions of America, During the Years 1799-1804.