Tuesday, November 29, 2011

Tungurahua (Ecuador) Volcano Has Major Explosion


Tungurahua volcano, one of Ecuador's most active volcanoes, had a major explosion which began suddenly without warning. The ash column reached some 3 kilometers in the sky, with reports of incandescent lava being spewed out up to 300 meters from the summit, and 500 meters down the slopes. Tungurahua has, since 1999, displayed frequent explosive eruptions generating pyroclastic flows, lava bombs, and tephra. It has been active throughout historical time.

Tungurahua viewed from Juive Grande, Ecuador (AFP, Pablo Cozzaglio)

(From the Smithsonian GVP:)
Tungurahua, a steep-sided andesitic-dacitic stratovolcano that towers more than 3 km above its northern base, is one of Ecuador's most active volcanoes. Three major volcanic edifices have been sequentially constructed since the mid-Pleistocene over a basement of metamorphic rocks. Tungurahua II was built within the past 14,000 years following the collapse of the initial edifice. Tungurahua II itself collapsed about 3000 years ago and produced a large debris-avalanche deposit and a horseshoe-shaped caldera open to the west, inside which the modern glacier-capped stratovolcano (Tungurahua III) was constructed. Historical eruptions have all originated from the summit crater. They have been accompanied by strong explosions and sometimes by pyroclastic flows and lava flows that reached populated areas at the volcano's base. Prior to a long-term eruption beginning in 1999 that caused the temporary evacuation of the city of Baños at the foot of the volcano, the last major eruption had occurred from 1916 to 1918, although minor activity continued until 1925.

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