Amir Tejo & Nurfika Osman
Surabaya & Jakarta. The build-up of sediments from the Lapindo mud volcano in an estuary in Sidoarjo, East Java, could trigger flooding in the nearby district of Pasuruan, scientists warned.
The mud volcano has spewed tens of thousands of cubic meters of hot mud and gas every day since a gas drilling accident in 2006, swamping much of the Porong subdistrict in Sidoarjo.
Authorities have since built levees to contain the vast lake of mud and channeled some of the mud out to sea through the Porong River.
On Wednesday, Wahyudi Tjitrosiswoyo, the head of the Terrestrial Disaster Study Center at the Sepuluh Nopember Institute of Technology (ITS) in Surabaya, said the sedimentation in the river’s estuary was building up at an alarming rate and could block the normal water flow, forcing the river and other waterways to burst their banks.
He said the river leads out to the Java Sea, which has “a flat or gently sloping seabed.”
“That means the mud isn’t washing out to sea quickly enough and is inhibiting the flow of the water, which will go back right up into the river and other waterways in the Porong estuary.
“This puts areas such as Bangil subdistrict in Pasuruan at risk of flooding because they have several waterways leading to the estuary,” he added.
Mukhtasor, another ITS researcher, said the sedimentation also caused the gradual destruction of the coastal marine ecosystem in the estuary.
“The mud blocks the sunlight penetrating into the water, which kills off the plankton and all the higher life forms that depend on it,” he said.
“The damage to the coastal ecosystem between may and October 2006 has been estimated at Rp 5 trillion.”
Mukhtasor said the cost to date would be exponentially bigger, as would the extent of the damage to the ecosystem.
Meanwhile, a group of Russian scientists said the mud volcano was a purely natural disaster that was “impossible to stop.”
“It’s impossible to stop nature,” Sergey Kadurin, a professor from Moscow’s Institute of Electro-Physical Problems, said on Wednesday.
“All you can do is monitor geological hazards, such as through a seismic detector.”
He said the Sidoarjo incident had been triggered by “subsurface seismic events such as earthquakes in 2005 and 2006.”
On July 9, 2005, a magnitude-4.4 earthquake struck Sidoarjo, while on May 27, 2006, a magnitude-6.3 quake hit Yogyakarta several hundred kilometers to the west.
The mud volcano erupted on May 28 that year, the same day that drilling company Lapindo Brantas experienced a blowout in one of its natural gas wells.
Independent experts have previously blamed the company’s drilling for the mud flow.
But Kadurin said there were currently 15 known mud volcanoes in East Java province, any of which could erupt from “a little tectonic pressure.”
He said the large number of mud volcanoes, coupled with the high level and frequency of tectonic activity in Indonesia, made such eruption almost inevitable.
On the other hand, Yuriy P. Rakintsev from RINeftGaz, a joint Russian-Indonesian oil and gas company, said the Sidoarjo mud volcano had erupted at the “wrong time and wrong place.”