Report on Sangay (Ecuador) — 11 May-17 May 2016
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 11 May-17 May 2016
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2016. Report on Sangay (Ecuador). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 11 May-17 May 2016. 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 at the beginning of March Sangay began a new phase of activity which continued through at least 12 May without significant changes. The number of tremor events and long-period earthquakes were slightly higher in March as compared to the number recorded in April and May, and the number of explosions was slightly higher in April and May. Surficial activity was characterized by frequent ash emissions generated by explosive activity. Thermal anomalies on the flanks were also detected, mostly within 5 km of the summit crater, which possibly corresponded to short-range pyroclastic flows and lava flows. No abnormal sulfur dioxide emission were detected.
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.