Report on Tungurahua (Ecuador) — 13 August-19 August 2014
Smithsonian / US Geological Survey Weekly Volcanic Activity Report,
13 August-19 August 2014
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2014. Report on Tungurahua (Ecuador). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 13 August-19 August 2014. Smithsonian Institution and US Geological Survey.
1.467°S, 78.442°W; summit elev. 5023 m
All times are local (unless otherwise noted)
During 13-19 August IG reported that moderate to high eruptive activity continued at Tungurahua, including volcanic tremor, blasts, and long-period and volcano-tectonic earthquakes. On most days cloudy conditions allowed only intermittent views of the volcano. On 14 August a “canon blast” sound shook structures in the town of Baños, followed by an ash plume that rose 1.5 km (4,900 ft) a.s.l. and drifted SW. On 13 August a lahar was reported in the Chontapamba sector that moved blocks 50 cm in size. On 15 August during the early morning an explosion and rockfall was heard and a light ashfall was reported in Choglontus. On 17 August glow was observed in the crater. On 18-19 August a fine black ashfall was reported in the areas of Pillate, Chontapamba, Bilbao, Mocha, Motilones, Quero, and Tisaleo. On 19 August a plume rose 2-3 km (6,600-9,800 ft) a.s.l. and drifted W and NW. During 13-19 August the Washington VAAC reported ongoing emissions, including volcanic ash and steam-and-gas plumes. On 14 August a short duration explosion and volcanic ash was reported.
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 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.