Report on Tungurahua (Ecuador) — 30 December-5 January 2010
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 30 December-5 January 2010
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2009. Report on Tungurahua (Ecuador). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 30 December-5 January 2010. Smithsonian Institution and US Geological Survey.
1.467°S, 78.442°W; summit elev. 5023 m
All times are local (unless otherwise noted)
The IG reported steam emissions from Tungurahua during 30 December-3 January. On 1 January, an ash plume rose to an altitude of 5.9 km (19,500 ft) a.s.l. and drifted NW. Slight ashfall was reported the next day in Manzano, 8 km SW. Roaring noises and incandescence from the crater were also reported. On 3 and 4 January, incandescent blocks were ejected from the crater. Based on information from the Guayaquil MWO and SIGMET notices, the Washington VAAC reported that ash plumes rose to altitudes of 6.7-9.1 km (22,000-30,000 ft) a.s.l. and drifted W. Thermal anomalies were detected in satellite imagery. On 4 January, ashfall was reported in areas to the W and SW.
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.