Report on Sangay (Ecuador) — 1 July-7 July 2020
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 1 July-7 July 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, 1 July-7 July 2020. Smithsonian Institution and US Geological Survey.
2.005°S, 78.341°W; summit elev. 5286 m
All times are local (unless otherwise noted)
On 2 July IG presented additional results from the Sangay overflight that was conducted on 24 June with the purpose of performing maintenance on a gas and seismic station, taking visual and infrared photos of the surficial activity, and measuring volcanic gases. Three thermal anomalies were identified: the first was in the summit crater and associated with explosions, the second was near the SE rim of the summit crater and possibly highlighted a small lava flow, and the third corresponded to the accumulation of hot deposits of pyroclastic flows at the lower part of the SE drainage. Ash from summit explosions and pyroclastic flows that descended the SE flank dispersed mainly S and W. Notable morphological changes to the summit areas were evident when comparing photographs from 17 May 2019 to 24 June 2020. The maximum width of the SE flank drainage was an estimated 397 m. Due to a large amount of airborne ash in the N, E, and S parts of the volcano, the SAGA station on the SW flank could not be reached and repaired. Winds caused ashfall in populated areas. Gas emission data could also not be obtained due to the amount of airborne ash.
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.