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Report on Tungurahua (Ecuador) — 5 January-11 January 2011

Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 5 January-11 January 2011
Managing Editor: Sally Kuhn Sennert

Please cite this report as:

Global Volcanism Program, 2011. Report on Tungurahua (Ecuador). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 5 January-11 January 2011. Smithsonian Institution and US Geological Survey.

Volcano Profile |  Weekly Report (5 January-11 January 2011)


Tungurahua

Ecuador

1.467°S, 78.442°W; summit elev. 5023 m

All times are local (unless otherwise noted)


On 5 January IG reported that, after moderately-sized explosions during 24-25 December, activity at Tungurahua had decreased. IG noted that during this time seismicity decreased and explosions had not occurred, deflation was detected, sulfur dioxide emissions gradually reduced, and decreases in the amount of ash present in plumes was noted. Although cloudy weather often prevented observations during 5-11 January, steam plumes were occasionally observed and rose above the crater to low heights.

Geologic Background. 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 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, 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.

Source: Instituto Geofísico-Escuela Politécnica Nacional (IG)