Enormous craters in Siberia's permafrost may finally have a decisive explanation. They form when pressurized water causes cracks to form in the permafrost, triggering a sudden, explosive release of methane gas, scientists say.
The mysterious craters measure 160 feet (50 meters) deep and up to 230 feet (70 m) across, and first appeared on Russia's northern Yamal and Gydan peninsulas in 2014. Chunks of rock and ice strewn across the landscape around the craters indicated they were caused by giant explosions. These strange craters have never been found elsewhere in the Arctic.
