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Report on Cuicocha (Ecuador) — 3 October-9 October 2018


Smithsonian Institution / US Geological Survey
Weekly Volcanic Activity Report, 3 October-9 October 2018
Managing Editor: Sally Sennert.

Please cite this report as:

Global Volcanism Program, 2018. Report on Cuicocha (Ecuador) (Sennert, S, ed.). Weekly Volcanic Activity Report, 3 October-9 October 2018. Smithsonian Institution and US Geological Survey.

Weekly Report (3 October-9 October 2018)



0.308°N, 78.364°W; summit elev. 3246 m

All times are local (unless otherwise noted)

IG reported an increase in seismic activity at Cuicocha during 2-3 October, characterized by a total of 60 volcano-tectonic events recorded at the time of the report posting. The largest of these events, a M 2.5 at 1058 on 2 October, was reportedly slightly felt by a resident of Quiroga.

Geological Summary. The scenic lake-filled Cuicocha caldera is located at the southern foot of the sharp-peaked Pleistocene Cotacachi stratovolcano about 100 km N of Quito. Both Cotacachi and Cuicocha were constructed along the Otavalo-Umpalá fracture zone. Eruptive activity began about 4500 years ago and continued until about 1300 years ago. The 3-km-wide, steep-walled caldera was created during a major explosive eruption about 3100 years ago that produced nearly 5 km3 of pyroclastic-flow and fall deposits. Four intra-caldera lava domes form two steep-sided forested islands in the 148-m-deep lake. A pre-caldera lava dome is situated on the outer E side of the caldera. Pyroclastic-flow deposits cover wide areas around the low-rimmed caldera, primarily to the east. Gas emission continues from several locations in the caldera lake.

Source: Instituto Geofísico-Escuela Politécnica Nacional (IG-EPN)