This report out of New Orleans:
At least 4.5 billion cubic feet of natural gas
"This is the most vigorous methane eruption in modern human history," said John Kessler, a Texas AandM University
A methane bubble this large -- if able to escape from under the ocean floor through fissures, cracks and fault areas -- is likely to cause a gas explosion. With the emerging evidence of fissures, the tacit fear now is this: the methane bubble may rupture the seabed and may then erupt with an explosion within the Gulf of Mexico waters. The bubble is likely to explode upwards propelled by more than 50,000 psi of pressure, bursting through the cracks and fissures of the sea floor, fracturing and rupturing miles of ocean
Read the original story at Maggie's Notebook

Disturbing evidence is mounting that something frightening is happening deep under the waters of the Gulf of Mexico—something far worse than the BP oil gusher.

Warnings were raised as long as a year before the Deepwater Horizon disaster that the area of seabed chosen by the BP geologists might be unstable, or worse, inherently dangerous.

What makes the location that Transocean chose potentially far riskier than other potential oil deposits located at other regions of the Gulf? It can be summed up with two words: methane gas.

The same methane that makes coal mining operations hazardous and leads to horrendous mining accidents deep under the earth also can present a high level of danger to certain oil exploration ventures.

Location of Deepwater Horizon oil rig was criticized

More than 12 months ago some geologists rang the warning bell that the Deepwater Horizon exploratory rig might have been erected directly over a huge underground reservoir of methane.