NEW ORLEANS – It is an overlooked danger in the oil spill crisis: The crude gushing from the well contains vast amounts of natural gas that could pose a serious threat to the Gulf of Mexico’s fragile ecosystem.

The oil emanating from the seafloor contains about 40 percent methane, compared with about 5 percent found in typical oil deposits, said John Kessler, a Texas A&M University oceanographer who is studying the impact of methane from the spill.

That means huge quantities of methane have entered the Gulf, scientists say, potentially suffocating marine life and creating “dead zones” where oxygen is so depleted that nothing lives.

“This is the most vigorous methane eruption in modern human history,” Kessler said.

Methane is a colorless, odorless and flammable substance that is a major component in the natural gas used to heat people’s homes. Petroleum engineers typically burn off excess gas attached to crude before the oil is shipped off to the refinery. That’s exactly what BP has done as it has captured more than 7.5 million gallons of crude from the breached well.

A BP spokesman said the company was burning about 30 million cubic feet of natural gas daily from the source of the leak, adding up to about 450 million cubic feet since the containment effort started 15 days ago. That’s enough gas to heat about 450,000 homes for four days.

But that figure does not account for gas that eluded containment efforts and wound up in the water, leaving behind huge amounts of methane. Scientists are still trying to measure how much has escaped into the water and how it may damage the Gulf and it creatures.