Emergency services refuse to comment cause of extraordinary blast in the dark sky.

Experts still divided over mysterious 1,300-year-old fortress-like structure located on island in middle of lake.

Reindeer herders find more craters in the far north in a deepening puzzle for scientists. 

Mysterious 'gigantic' hole in remote region spotted by helicopters over gas-rich Yamal peninsula.

Giant sinkhole threatens more homes as it widens each week.

High levels of ‘fire ice’ trapped in permafrost may turn Russia into a global leader of new gas sources.

'Absolutely stunning' ancient ornaments discovered with no known comparisons, presenting a puzzle for archeologists: which culture made this?

These are the first pictures and video of scene in Khabarovsk region where a sudden and massive rock movement causes semi-blockage and flood risk.

Satellites show giant hole ringed by 20 'baby craters'.