Natural gas leaks from underground are natural geological phenomena that occur worldwide, but they gain the most dramatic attention when the gas ignites. This phenomenon โ called burning natural gas "seeps" โ produces a continuous release of fire, sometimes for centuries.
The gas most frequently involved is methane (CHโ) โ the primary component of natural gas. Methane is produced through the decomposition of organic matter by anaerobic bacteria under specific underground conditions, or it is trapped as a byproduct in oil and gas deposits. When geological pressure allows the gas to leak to the surface, it can ignite when exposed to a heat source or spark.
The Darvaza Gas Crater in Turkmenistan โ popularly nicknamed the "Door to Hell" โ is among the most famous examples, although not entirely natural. In 1971, Soviet geologists drilled into what was thought to be an oil deposit, which turned out to be a large cavern of gas. The ground around it collapsed, forming a crater about 70 meters in diameter. To prevent the release of toxic gas into the surrounding area, it was set on fire with the assumption that it would burn out in a few days. The gas is still burning 50 years later.
There are more purely natural examples: "Eternal Flame Falls" in New York, where a small flame burns behind a waterfall, fueled by methane gas leaking from shale deposits; "Burning Mountain" in New South Wales, Australia, where a coal seam has been burning for over 6,000 years; and various locations worldwide where natural fires occur.
Chemically, the process of methane combustion is simple: CHโ + 2Oโ โ COโ + 2HโO. However, its climate change implications are significant โ unburned leaking methane is 86 times more potent than COโ as a greenhouse gas over a 20-year period. Combustion converts it to less potent COโ, although COโ itself is a problem.