Sunday 26 August 2012

Seismic activity beneath Mount Sotará, Columbia.

The Observatorio Vulcanológico and Sismológico de Popayán reported a sharp rise in seismic activity under Mount Sotará in southeast Columbia this month, with 110 Earth tremors of magnitudes between 0.2 and 1.6 at depths of 2-6 km, within 5 km of the summit between the 8th and 14th of August 2012. Such quakes can be the result of magma moving into chambers beneath a volcano, which in turn may be a prelude to an eruption. 

Areal photograph of Mount Sotará taken in December 2007. The 'smoke' around the crater is probably just low cloud. Observatorio Vulcanológico and Sismológico de Popayán.

Mount Sotará is a stratovolcano (cone-shaped volcano made up of layers of ash and lava) slightly over 4400 m high. It has not erupted in recorded history, although it has produced fumaroles (gas emissions), and a complex of hot springs to the southeast is thought to be associated with the volcano.

Like other volcanoes along the west coast of South America, Mount Sotará is fueled by the subduction of the Nazca Plate (which underlies the southeastern Pacific Ocean) beneath the South American Plate. As the Nazca Plate passes under South America it is partially melted by the friction and the heat of the planet's interior. Some of this melted material then rises through the South American Plate, feeding the volcanoes of the Andes.

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