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Report on Tungurahua (Ecuador) — 18 July-24 July 2001

Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 18 July-24 July 2001
Managing Editor: Gari Mayberry

Please cite this report as:

Global Volcanism Program, 2001. Report on Tungurahua (Ecuador). In: Mayberry, G (ed.), Weekly Volcanic Activity Report, 18 July-24 July 2001. Smithsonian Institution and US Geological Survey.

Volcano Profile |  Weekly Report (18 July-24 July 2001)


Tungurahua

Ecuador

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

All times are local (unless otherwise noted)


During the week heavy rain remobilized ash deposited on the flanks of the volcano, generating lahars, and several small-to-moderate eruptions produced ash clouds. On 19 July lahars that traveled down the W flank of the volcano reached the Baños-Riobamba highway. The Washington VAAC reported that one of the larger eruptions during the week occurred on 20 July at 2104 and produced an ash cloud that rose to ~7.9 km a.s.l.

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.

Sources: Instituto Geofísico-Escuela Politécnica Nacional (IG), Washington Volcanic Ash Advisory Center (VAAC)