There was an article on this in the Jan. National Geographic. Unfotunately not produced in full on the web site. Richard Davies's main points.
1. Drillers exploring for gas bored 3,580
feet down, then inserted a steel casing
to strengthen the hole.
2. Drilling went deeper without the steel
casing. Water and gas filled the hole,
and the resulting pressure fractured
unprotected rock strata.
3. Hot, high-pressure water was released,
probably from the Kujung aquifer.
4. The water raced upward and liquefied
masses of mudstone.
5. Mud surged through layers of
mudstone and sandstone and broke
through the surface.
6. Engineers built dikes in an attempt
to contain the mud.
7. Underground, caverns formed and
collapsed, causing faults.
Also the company, PT Lapindo Brantas is parly owned by the family of Aburizal Bakrie.. Indonesia's chief welfare minister who is a billionaire. Well we are talking Indonesia.
http://ngm.nationalgeographic.com/2008/01/volcano-culture/drowning-in-mud-text/1
The past is a foreign country: they do things differently there.