Report on Sangay (Ecuador) — 23 September-29 September 2020
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 23 September-29 September 2020
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2020. Report on Sangay (Ecuador). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 23 September-29 September 2020. Smithsonian Institution and US Geological Survey.
2.005°S, 78.341°W; summit elev. 5286 m
All times are local (unless otherwise noted)
IG issued a report with additional information about the large explosive event at Sangay on 20 September. The event began at 0440 and ended at 0610 and produced an ash plume that rose 15 km (49,200 ft) a.s.l., or about 9.7 km above the summit. The lower part of the plume was the most ash-rich and drifted W, causing significant ashfall in areas W (especially in the Cebadas parish, Guamote district). The gas-rich higher part of the plume drifted E. Parts of the plume also drifted S. Researchers visited several sites to measure ashfall and collect samples, allowing them to estimate the volume of the deposits at 1.5-3.4 million cubic meters, signifying a VEI 2 event.
Geologic Background. The isolated Sangay volcano, located east of the Andean crest, is the southernmost of Ecuador's volcanoes and its most active. The steep-sided, glacier-covered, dominantly andesitic volcano grew within horseshoe-shaped calderas of two previous edifices, which were destroyed by collapse to the east, producing large debris avalanches that reached the Amazonian lowlands. The modern edifice dates back to at least 14,000 years ago. It towers above the tropical jungle on the east side; on the other sides flat plains of ash have been sculpted by heavy rains into steep-walled canyons up to 600 m deep. The earliest report of a historical eruption was in 1628. More or less continuous eruptions were reported from 1728 until 1916, and again from 1934 to the present. The almost constant activity has caused frequent changes to the morphology of the summit crater complex.