Mysterious 'gigantic' hole in remote region spotted by helicopters over gas-rich Yamal peninsula.
Three man team probing the discovery is now 'missing in tundra', say Emergency Ministry officials.
Subsidence from old coal mine a possible cause of latest mystery hole.
Russian scientists deny theory of respected Italian team by 'proving' that the remote blue lake is older than the famous 1908.
An earthquake in the vicinity of the Russian Far Eastern city of Petropavlovsk-Kamchatsky can be expected in the coming days, say scientists.
Epicentre was in mountains of Kamchatka peninsula with a powerful 7.3 magnitude.
Siberian scientist leads team making unexpected discovering in Kyrgyzstan.