Mysterious craters exploded in Siberia’s permafrost. Scientists say they now know why

A decade ago, a mysterious crater appeared in the Russian Arctic, forming a huge jagged hole hundreds of feet wide. Since then more than 20 have formed, leaving scientists baffled and intrigued

​ A decade ago, a mysterious crater appeared in the Russian Arctic, forming a huge jagged hole hundreds of feet wide. Since then more than 20 have formed, leaving scientists baffled and intrigued Read More Breaking News, Latest News and Videos | CNN