Three man team probing the discovery is now 'missing in tundra', say Emergency Ministry officials.
Bulging bumps in the Yamal and Gydan peninsulas believed to be caused by thawing permafrost releasing methane.
Subsidence from old coal mine a possible cause of latest mystery hole.
Earth is moving as 'leaking methane gas due to global warming causes surface to bubble' in a new phenomenon.
Startling new details emerge of the most mysterious of Siberia's newly created giant permafrost holes.
Same phenomenon of discharge of gas hydrates 'led to crater formation in Russia and disappearance of ships in Atlantic'.
Giant holes created when pingos erupted after filling with gas.
More craters expected to form due to such eruptions as permafrost melts - and they ARE caused by global warming releasing methane gas.