Friday 16 November 2012

Eruption on Volcán El Reventador.

Volcán El Reventador is a 3562 m volcano rising out of the jungle of the western Amazon Basin, and considered to be one of the most active volcanoes of the Ecuadorean Cordillera Real. The volcano comprises a on older, forested, 4 km wide caldera, open to the east, with a younger, unforested, active stratovolcano (cone shaped volcano) within, rising 1300 m above the caldera floor. The recorded history of Volcán El Reventador goes back to April 1541, with at least 25 major eruptions in this time, though it is quite likely that some will have been missed, due to the remote location of the volcano. The largest recorded eruption on Volcán El Reventador occurred in 2008, when an ash-column rose 6 km into the air and was accompanied by explosions, pyroclastic flows, lava flows and lahars.

A steam plume rising above Volcán El Reventador in February 2012. Endless River Adventures.

Volcán El Reventador has produced columns of ash and steam for much of 2012, but has otherwise been inactive. On 3-4 November an ash plume rose 3 km above the summit, and on 9 November, following a visit to the site by volcanologists, the Instituto Geofísico-Escuela Politécnica Nacional reported a new phase of activity had started on the mountain, with lava flows on the north and south flanks of the volcano, up to 2 km in length, and a lava dome (mound-shaped protrusion resulting from the slow extrusion of viscous lava) rising above the crater walls. On 13 November the Washington Volcanic Ash Advisory Center reported an ash column from Volcán El Reventador rising 5.2 km and drifting to the southeast.

The volcanoes of the Cordillera Real, and of South America in general, are fueled by the subduction of the Nazca Plate beneath the South American Plate. The Nazca Plate underlies a large chunk of the eastern Pacific Ocean, and is being subducted along Peru-Chile Trench to the west of South America. As it sinks into the Earth, the Nazca Plate passes under South America, where it is heated by friction with the overlying South American Plate and by the heat of the planet's interior. This causes the Nazca Plate to partially melt, and some of this melted material then rises through the South American Plate as magma, fueling the volcanoes of the Andes. The motion of one plate beneath another is not a smooth process, and the Nazca and South American Plates frequently stick together, then break apart as the pressure builds up, triggering frequent Earthquakes along the western coast of South America, and sometimes further inland.

The subduction of the Nazca Plate beneath the South American Plate, and how it causes Earthquakes and volcanoes. SIO SEARCH.

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