Report on Tungurahua (Ecuador) — 13 March-19 March 2013
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 13 March-19 March 2013
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2013. Report on Tungurahua (Ecuador). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 13 March-19 March 2013. Smithsonian Institution and US Geological Survey.
1.467°S, 78.442°W; summit elev. 5023 m
All times are local (unless otherwise noted)
IG reported that during 13-17 March seismicity at Tungurahua was high. On 13 March ash plumes rose 1-3 km above the crater, and generated ashfall in Choglontús (SW) and Puela (8 km SW). The next day nearly continuous emissions of gas and ash rose 500 m. Explosions produced ash plumes that rose 3 km; ash fell between the Mapayacu (SW) and Rea drainages, and in Choglontús, Cahuají (8 km SW), and El Manzano (8 km SW). Blocks rolled 500 m down the flanks. On 15 March ash plumes drifted SE and W. An explosion generated an ash plume that rose 4 km and drifted E. A pyroclastic flow occurred near the crater. Explosions on 16 March generated ash plumes; ashfall was reported in Puela, Pillate (8 km W), and Ambato (31 km NW). On 17 March explosions again produced ash plumes that rose 4 km. Lava fountains rose 200-300 m above the crater and incandescent material fell on the flanks. A pyroclastic flow descended the upper parts of the Mandur (NW) drainage. Ashfall was reported in El Manzano, Palictagua and Choglontús.
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.