Report on Cotopaxi (Ecuador) — 31 May-6 June 2023
Smithsonian Institution / US Geological Survey
Weekly Volcanic Activity Report, 31 May-6 June 2023
Managing Editor: Sally Sennert.
Please cite this report as:
Global Volcanism Program, 2023. Report on Cotopaxi (Ecuador) (Sennert, S, ed.). Weekly Volcanic Activity Report, 31 May-6 June 2023. Smithsonian Institution and US Geological Survey.
0.677°S, 78.436°W; summit elev. 5911 m
All times are local (unless otherwise noted)
IG reported that moderate eruptive activity continued at Cotopaxi during 30 May-6 June. Seismic activity was mainly characterized by long-period earthquakes and tremors associated with daily emissions. Although weather clouds often obscured views, emissions were visible almost daily. During 30-31 May ash-and-gas emissions rose as high as 500 m above the summit and drifted W and NW. A tremor signal associated with an ash emission was detected on 1 June, though weather clouds prevented visual confirmation; ashfall was reported in San Ramón (108 km N) and San Agustín de Callo (16 km WSW). Multiple ash emissions were reported on 3 June; ash plumes rose as high as around 1 km above the summit and drifted SW, W, and NW. During 4-5 June several gas-and-ash emissions rose 400-800 m and drifted W and SW. Servicio Nacional de Gestión de Riesgos y Emergencias (SNGRE) maintained the Alert Level at Yellow (the second lowest level on a four-color scale).
Geological Summary. The symmetrical, glacier-covered, Cotopaxi stratovolcano is Ecuador's most well-known volcano and one of its most active. The steep-sided cone is capped by nested summit craters, the largest of which is about 550 x 800 m in diameter. Deep valleys scoured by lahars radiate from the summit of the andesitic volcano, and large andesitic lava flows extend to its base. The modern edifice has been constructed since a major collapse sometime prior to about 5,000 years ago. Pyroclastic flows (often confused in historical accounts with lava flows) have accompanied many explosive eruptions, and lahars have frequently devastated adjacent valleys. Strong eruptions took place in 1744, 1768, and 1877. Pyroclastic flows descended all sides of the volcano in 1877, and lahars traveled more than 100 km into the Pacific Ocean and western Amazon basin. Smaller eruptions have been frequent since that time.