"The list of possible natural explanations for the giant hole includes a meteorite strike and a gas explosion, or possibly an eruption of underground ice."
"Anna Kurchatova from Sub-Arctic Scientific Research Centre thinks the crater was formed by a water, salt and gas mixture igniting an underground explosion, the result of global warming. She postulates that gas accumulated in ice mixed with sand beneath the surface, and that this was mixed with salt – some 10,000 years ago this area was a sea."