Thursday 28 June 2012

Possible volcanic activity on Mount Siple, Antarctica.

Mount Siple is one of the world's most remote volcanoes, located on Siple Island, off the coast of Marie Byrd Land, Antarctica. It is a shield volcano (volcano with a fairly flat profile made up mostly of layers of lava) 3110 m in height, and thought to be quite young (less than 10 000 years), though its geology has not been well studied due to its remote location. It's topography has only ever been recorded by sketch map, and if the summit has ever been climbed, then the event has never been recorded.

Areal photograph of Mount Siple. Smithsonian Global Volcanism Program/US Navy.

On 20 June 2012 the European Metop Satellite detected an apparent volcanic plume issuing from Mount Siple; the Metop Satellite does not produce visual images, so it is not completely certain this is what it was seeing. The satellite witnessed temperatures on Mount Siple rise to a balmy -22 ℃, against a background temperature of -28 ℃, and produced infrared imagery of what appeared to be a plume of steam with a temperature of -55 ℃ at its base.

Mount Siple, and the other volcanoes of Marie Byrd Land, are located on the western margins on the  West Antarctic Rift System, which appears to be slowly splitting Antarctica in two in a similar way to the Great Rift Valley in Africa (though the geology of the region is not nearly as well studied). Marie Byrd Land is apparently starting to pull away from the rest of the continent, and between the two regions an area of rifting has developed, with upwellings of magma feeding volcanism in Marie Byrd Land and the Transantarctic Mountains.

Map showing the extent of the West Antarctic Rift System. Abbreviations: AR, Ames Range; BSB, Byrd Subglacial Basin; BST, Bentley Subglacial Trough; CM, Crary Mountains; ECR, Executive Committee Range; FR, Flood Range; MM, Mount Murphy; MS, Mount Siple; MT, Mount Takahe; TM, Toney Mountain. Paulsen & Wilson (2010).

Simplified diagram showing the evolution from a Rift Valley to a full Ocean Basin, using the African Rift Valley, the Red Sea and the Atlantic Ocean as examples. This is essentially the same process as that which is starting along the West Antarctic Rift. Hannes Grobe, Alfred Wegener Institute for Polar and Marine Research/Wikipedia