The saga deepened. The Siberian crater wasn’t alone. There were two more, ratcheting up the tension in a drama that hit its climax as a probable explanation surfaced. Global warming had thawed the permafrost, which had caused methane trapped inside the icy ground to explode. “Gas pressure increased until it was high enough to push away the overlaying layers in a powerful injection, forming the crater,” one German scientist said at the time.

Now, however, researchers fear there are more craters than anyone knew — and the repercussions could be huge. Russian scientists have now spotted a total of seven craters, five of which are in the Yamal Peninsula. Two of those holes have since turned into lakes. And one giant crater is rimmed by a ring of at least 20 mini-craters, the Siberian Times reported. Dozens more Siberian craters are likely still out there, said Moscow scientist Vasily Bogoyavlensky of the Oil and Gas Research Institute, calling for an “urgent” investigation.

http://www.washingtonpost.com/news/morning-mix/wp/2015/02/26/the-siberian-crater-problem-is-more-widespread-and-scarier-than-anyone-thought/?hpid=z4
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