"The striking puncture in the earth is believed to be up to 80 metres wide but its depth is not estimated yet. A scientific team has been sent to investigate the hole and is due to arrive at the scene on Wednesday. The cause of its sudden appearance in Yamal - its name means the 'end of the world' in the far north of Siberia - is not yet known, though one scientific claim is that global warming may be to blame. There is additionally speculation it could be caused by a space object - perhaps a meteorite - striking earth or that it is a sinkhole caused by collapsing rock beneath the hole caused by as yet unknown factors. The giant hole appeared close to a forest some 30 kilometres from Yamal's biggest gas field Bovanenkovo. Experts are confident that a scientific explanation will be found for it and that it is not - as one web claim suggested - evidence 'of the arrival of a UFO craft' to the planet. A report and footage highlighted by Zvezda TV says the dark colour of the crater indicates 'some temperature processes', without explaining more what they may mean. Others say that the darkening around the inner rim indicates its formation was accompanied by severe burning scorching the edges. Some observers believe water or dry soil is seen falling into the cavity."