Wednesday, 21 September 2016

Airports closed after eruptions on Mount Turrialba.

Several airports in Costa Rica were forced to close after a pair of eruptions on Mount Turrialba, a stratovolcano (cone shaped volcano made up of layers of ash and lava) in the central part of the country, Monday 19 September 2016. The first eruption occured at about dawn, the second at about noon, this latter event producing an ash column over four kilometers high, and causing ashfalls in the city of Cartago. A third eruption occured on Tuesday 20 September.

Eruption on Mount Turrialba on Monday 19 September 2016. Red Sismológica Nacional/Universidad de Costa Rica.

Volcanic ash is extremely hazardous to aircraft in a number of ways. At its most obvious it is opaque, both visually and to radar. Then it is abrasive, ash particles physically scour aircraft, damaging components and frosting windows. However the ash is most dangerous when it is sucked into jet engines, here the high temperatures can melt the tiny silica particles, forming volcanic glass which then clogs engine. When this happens the only hope the aircraft has is to dive sharply, in the hope that cold air passing through the engine during the descent will cause the glass to shatter, allowing the engine to be restarted.

 Residents of Cartago during an ashfall event on Monday 19 September 2016. AFP.

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 fueled 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.

See also...

http://sciencythoughts.blogspot.co.uk/2016/05/exclusion-zone-established-around-mount.htmlExclusion zone established around Mount Turriabla after a series of eruptions on Sunday 1 May 2016.                                    The Costa Rican Comisión Nacional de Emergencias has...
http://sciencythoughts.blogspot.co.uk/2016/05/eruptions-on-mount-turrialba.htmlEruptions on Mount Turrialba                         The Observatorio Vulcanológico y Sismológico de Costa Rica-Universidad Nacional reported a series of eruptions on Mount Turrialba, a stratovolcano (cone shaped volcano made up of layers of ash and lava) in the central part of...
http://sciencythoughts.blogspot.co.uk/2015/12/explosive-eruption-on-mount-turrialba.htmlExplosive eruption on Mount Turrialba. The Observatorio Vulcanológico y Sismológico de Costa Rica-Universidad Nacional reported a short explosive eruption which lasted about ten minutes, beginning slightly after 1.10 pm local time on Monday 7 December 2015...
 
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