Formation of giant Siberian gas emission craters (GECs)

The recent discovery of eight gas escape craters (GECs) in Western Siberia has challenged researchers for the past decade. The GECs have only been observed in this limited region. Several models have been proposed with the commonality that they formed from permafrost-internal processes triggered by external forcing. Numerical modeling, however, suggests that the estimated volume of ejecta may not be in agreement with gas-filled cavities of limited size. Furthermore, a rigorous analysis of attainable pressures by permafrost-internal processes has not been done. This study critically reviews the existing models and concludes that focused deep heat and gas from below the permafrost may be the key factor allowing the formation of GECs, while atmospheric heating indirectly triggers their formation by accelerating cryogenic process rates and the formation of new lakes and rivers. GECs appear to be associated with faulting in the area and form where sub-lake or sub-river talik structures meet local thinning of the permafrost.