Methane outbursts due to melting permafrost in Siberia: the Yamal crater

Image from the Washington Post here

Update: Of interest may be Alan Weisman's August 12, 2014 article "Why the Earth is farting." Also, see reader comment.

Several months ago, a photo of a crater discovered by a helicopter crew  went viral. It is located in the Yamal Peninsula in Siberia, a desolate spit of land. The crater was variously reported to be 100- 200 feet in diameter. In the July 31 issue of Nature, highlighted in the Washington Post article referenced in the adjacent figure caption, the discovery of two nearby craters is reported in the Washington Post article. The article contains an excellent video taken from a helicopter showing the crater walls actively crumbling. A camera has been lowered to 50 m, and it showed a pool of water at a depth of 70 meters, so the crater extends below 70 m.

Image from Washington Post here

Russian researcher Andrei Plekhanov led an expedition to the crater. He found that near the bottom of the crater (at approximately 50 m depth) air contained concentrations of methane up to 9.6%. That is to be compared to the normal concentration of methane in air--0.000179%. They believe that the abnormally hot summers in Yamai in 2012 and 2013 caused permafrost to thaw. Under the permafrost, usually at depths of 100 meters, methane clathrates are stable. Over the past 20 years, permafrost at a depth of 20 meters has warmed by about 2 C according to the article, quoting Hans-Wolfgang Hubberten of the Alfred Wegener Institute in Potsdam, Germany. Hubberten speculates that a thick layer of ice overlying the clathrates allowed gas pressure to increase until it was great enough to blow out in an explosive burst, forming the crater with rubbly ejecta strewn around it.
     The development of more craters could pose a danger to villages of local reindeer herders, and the craters are only 30 km from a large gas field, the Bovanenkovskoye gas field. A blowout in the gas field cold be very dangerous.