Report on Tungurahua (Ecuador) — 13 January-19 January 2010
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 13 January-19 January 2010
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2010. Report on Tungurahua (Ecuador). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 13 January-19 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 that during 13-14 January explosions from Tungurahua ejected incandescent material 1 km above and 1.5 km away from the crater, onto the flanks. Explosions produced noises resembling "cannon shots" and caused windows and structures to vibrate. Gas-and-ash plumes rose to altitudes of 7-8 km (23,000-26,000 ft) a.s.l. and drifted W and SW, causing ashfall. On 15 January, although meteorological clouds mostly prevented observations, an ash plume was seen rising to an altitude of 6 km (19,700 ft) a.s.l. Cloud cover prevented observations during the next two days. On 17 January, ashfall was reported in areas W and SW. Lahars descended drainages to the W and NW, causing the road to Baños to close. On 18 January, Strombolian activity ejected incandescent blocks and an ash plume rose to an altitude of 6 km (19,700 ft) a.s.l. Explosions caused windows and structures to vibrate. Ashfall was reported in areas W and SW on 18 and 19 January.
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.