Scientists are struggling to explain the appearance of a giant sinkhole in the Yamal Peninsula, a remote region of Russia that translates as 'the end of the world'.
So far theories have ranged from meteorite strikes to subsurface ice, and even UFOs, however no answer has yet been found, reports Mail Online.
A research team sent to investigate the phenomenon is hoping to unearth more information about the baffling feature.
Aerial images suggest it may be up to 260 feet (80 metres) wide, however has an unknown depth.
According to the Sunday Morning Herald the predominant theory so far is that the feature is a ‘pingo’.
A pingo is a large chunk of ice that is located underground that can create a hole in the ground when it melts.
“Certainly from the images I’ve seen it looks like a periglacial feature, perhaps a collapsed pingo,” said Dr Chris Fogwill of the University of New South Wales.
He said this is obviously a very extreme version of that, and if there’s been any interaction with the gas in the area, that is a question that could only be answered by going there.
Others, however, have pointed to the abundance of natural gas in the region as a possible explanation for the hole.
Geologist David Wilshaw, president of Florida-based geology business Britannia Solutions said it’s certainly mysterious.
“It's unlikely to be a meteor strike as it 'would not leave such a deep and steep sided hole, and the impact pattern would be different,'” he said.
“There is a ridge of material around the edge, so this suggests some kind of 'explosion' out of the ground.
Most likely it was caused by the explosion of a pocket of natural gas that had accumulated near to the surface, perhaps in an existing underground cavern system, that somehow either ignited – explaining the 'scorched' edge – or expanded until it reached some critical pressure that it blew the permafrost surface off,” he added.
Yamal has some of the world’s largest natural gas reserves, which has led to extensive pumping of the region.
This caused some experts to suggest the hole could be the consequence of a giant explosion underground.
The region is geologically young, about 10,000 years, and has the possibility of gas being trapped in ice beneath the surface. With global warming ice may have melted to released the gas.
Experts also say that the darkening around the inner rim of the crater indicates 'severe burning' which scorched its edges.
The expedition currently taking place is being organised by the Yamal authorities and includes experts from Russia's Centre for the Study of the Arctic, and also the Cryosphere Institute of the Academy of Sciences.
They plan to take samples of soil, air and water from the scene and they will be accompanied by a specialist from Russia's Emergencies Ministry in an attempt to solve the mystery once and for all.
