Report on Tungurahua (Ecuador) — 7 May-13 May 2008
Smithsonian Institution / US Geological Survey
Weekly Volcanic Activity Report, 7 May-13 May 2008
Managing Editor: Sally Sennert.
Please cite this report as:
Global Volcanism Program, 2008. Report on Tungurahua (Ecuador) (Sennert, S, ed.). Weekly Volcanic Activity Report, 7 May-13 May 2008. 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 although visual observations were occasionally limited due to cloud cover during 7-13 May, ash and steam plumes from Tungurahua were spotted most days and rose to altitudes of 5-8 km (16,400-26,200 ft) a.s.l. Ashfall was reported in areas within 8 km to the SW, W, N, and NW on 6, 10, and 11 May. On 8 May, muddy waters were reported in areas SW and S and roaring noises were audible. On 11 May, incandescence at the summit was reported along with roaring noises and blocks that rolled 1 km down the flanks. After an explosion on 12 May, windows vibrated, roaring noises were again reported, and rockfalls occurred in an area 8 km S.
Geological Summary. 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 collapsed about 3,000 years ago and produced a large debris-avalanche deposit to the west. The modern glacier-capped stratovolcano (Tungurahua III) was constructed within the landslide scarp. 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.