The University of Costa Rica’s National Seismological Network has reported a large eruption on Mount Turrialba, a 3340 stratovolcano (cone-shaped volcano made up of layers of ash and lava), in the central part of the country, on the morning of Tuesday 6 February 2018, which produced a column of ash that rose over a kilometer above the summit of the volcano. Turrialba has been more-or-less constantly active since December 2016, but this is the first eruption of 2018 to produce an eruptive column more than 500 m high.
Eruption on Mount Turrialba on Tuesday 6 February 2018. Red Sismológica Nacional/Universidad de Costa Rica.
Turrialba forms part of the Cordillera Central, a range of volcanic mountains running through central Costa Rica and forming part of the Central American Arc. These volcanoes are fuelled by the subduction of the Cocos Plate, which underlies part of the east Pacific Ocean, beneath the Caribbean Plate, on which Central America lies, along the Middle American Trench, which lies off the south coast of the country. As the Cocos Plate is subducted it is gradually melted by the heat and pressure of the Earth's interior, with some more volatile minerals rising through the overlying Caribbean Plate as volcanic magma.
Diagram showing the passage of the Cocos Plate beneath Costa Rica (not to scale). Carleton College.
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