Where are methane hydrate deposits situated? (from US Dept Energy)
Methane hydrates are known to occur both within and below permafrost in polar areas. Several areas in the Arctic show potential for having gas hydrate accumulations.
Three areas are in North America may have pressure and temperature conditions favourable to the formation of gas hydrates (US Department of Energy).
(1) northern Alaska,
(2) the Mackenzie Delta-Beaufort Sea region,
(3) Sverdrup basin of Canada,
"'Promising energy inventories' of methane hydrates have been described in Alaska,
the Canadian Arctic, ...Most promising for the US are Alaska’s North Slope, Blake’s Ridge, and the Gulf of Mexico.”
US, ALASKA & CANADA METHANE HYDRATE
5 February 2007
Methane bubbling through sea floor creates undersea hills called "pingo-like features."
Geophysical Research Letters,Origin of pingo-like features on the Beaufort Sea shelf and their possible relationship to decomposing methane gas hydrates geologists Charlie Paull and William Ussler Beaufort Sea Shelf off North coast of Canada.
The Arctic shelf is currently undergoing dramatic thermal changes caused by the continued warming associated with Holocene sea level rise. During this transgression, comparatively warm waters have flooded over cold permafrost areas of the Arctic Shelf. A thermal pulse of more than 10°C is still propagating down into the submerged sediment and may be decomposing gas hydrate as well as permafrost.
According to the paper methane gas bubbling through sea floor sediments has created hundreds of low hills on the floor of the Arctic Ocean. These features, which can grow up to 40 meters (130 feet) tall and several hundred meters across, The paper says the pingo-like features form when methane hydrate (a frozen mixture of gas and seawater) decomposes beneath the sea floor, releasing gas that squeezes deep sediments up onto the sea floor like toothpaste from a tube. Finally, many of the pingo-like features were surrounded by shallow "moats," where the sea floor within a kilometer of the hill had apparently subsided.
Methane Seepage From the Arctic Shelf; 20 Years of Research on the Beaufort Sea MarginLorenson, T. D.; Paull, C. K.; Collett, T. S.; Dallimore, S. R. US Geological Survey 2008.
The results of these studies show that gas hydrate is present and that methane source can be both microbial and thermogenic. In light of our rapidly changing climate, the instability and potential methane release from Arctic gas hydrate deposits are reemerging as pivotal uncertainties.
October 2012 Vast region of methane hydrates are destabilizing off the Eastern US
"We may approach a turning point" from a warming driven by man-made carbon dioxide to a warming driven by methane, Jurgen Mienert, the geology department chair at Norway's University of Tromso, told NBC News. "Interactions between the warming Arctic Ocean and the potentially huge methane-ice reservoirs beneath the Arctic Ocean floor point towards increasing instability," he added.
Beaufort Sea hydrate research ... The sediment was chock full of methane hydrates.
Dec 2014 Warmer Pacific Ocean could release millions of tons of seafloor methane - methane hydrate off N. American west coast. Research indicates the ocean warming is deep enough that hydrates will be releasing methane from N. California to West Alaska.
Oct 2014 Dissociation of Cascadia margin gas hydrates in response to contemporary ocean warming