There’s now a substantiated theory about what created the crater. And the news isn’t so good.
It may be methane gas, released by the thawing of frozen ground. According to a recent Nature article, “air near the bottom of the crater contained unusually high concentrations of methane — up to 9.6% — in tests conducted at the site on 16 July, says Andrei Plekhanov, an archaeologist at the Scientific Centre of Arctic Studies in Salekhard, Russia. Plekhanov, who led an expedition to the crater, says that air normally contains just 0.000179% methane.”
The scientist said the methane release may be related to Yamal’s unusually hot summers in 2012 and 2013, which were warmer by an average of 5 degrees Celsius. “As temperatures rose, the researchers suggest, permafrost thawed and collapsed, releasing methane that had been trapped in the icy ground,” the report stated.