Drilling blamed for Java mud leak

The mud leak has submerged several villages

A mud leak that has displaced thousands of Indonesians was most probably caused by drilling for gas, a scientific study into the disaster concludes.

The British-based scientists believe the drilling in East Java ruptured pressurised limestone rock, allowing water and mud to rise to the surface.

They warn thousands of cubic metres of mud a day could continue to spew out for months, if not years, to come.

An Indonesian minister has insisted the eruption is a natural disaster.

Welfare Minister Aburizal Bakrie - whose family firm controls the drilling firm involved, Lapindo Brantas - said it was caused by the devastating earthquake near Yogyakarta on 27 May.

His comments echo those made by Lapindo Brantas, which has denied a drilling accident was to blame.

Hot mud and gas have been spewing from the ground in Sidoarjo since early June, and show little sign of stopping.

The mud flow, made up of what is known locally as Lusi, has submerged several villages in the surrounding area and displaced more than 10,000 people.

Satellite images

The scientific survey, published in February's issue of the Geological Society of America's GSA Today, warns that between 7,000 and 150,000 cubic metres of mud a day could be spilled for months or years to come.

It says an area of some 10 sq km (3.9 sq miles) affected by the flow "will probably sag", and will be uninhabitable for years.

The mud flow has continued to spread since it erupted in May

The report also warns that the area around the mud hole could suffer a "dramatic collapse" to form a crater.

The team of scientists at Durham University analysed satellite images of the area for the study.

"It is standard industry procedure that this kind of drilling requires the use of steel casing to support the borehole, to protect against the pressure of fluids such as water, oil or gas," team leader Richard Davies said.

"In the case of Lusi, a pressured limestone rock containing water - a water aquifer - was drilled while the lower part of the borehole was exposed and not protected by casing.

"As a result, rocks fractured and a mix of mud and water worked its way to the surface. Our research brings to the conclusion that the incident was most probably the result of drilling."

The Indonesian government has been working to stem the flow with a network of dams and by channelling some of it into the sea, but with little success so far.