Report on Sangay (Ecuador) — 21 November-27 November 2018
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 21 November-27 November 2018
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2018. Report on Sangay (Ecuador). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 21 November-27 November 2018. Smithsonian Institution and US Geological Survey.
2.005°S, 78.341°W; summit elev. 5286 m
All times are local (unless otherwise noted)
IG reported that since 8 August activity at Sangay was characterized by the extrusion of lava flows on the ESE flank and ash emissions that rose between 500 and 1,500 m and mainly drifted W and NW. Lava flows were 1-2 km long, though block avalanches from the flow fronts traveled additionally as far as 5 km. The seismic network recorded more than 50 signals per day indicating explosions. The activity continued at least through 21 November; the report noted that this phase has lasted longer than any other since 2015.
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.