Instituto Geofísico-Escuela Politécnica Nacional (IG-EPN) reported that high levels of eruptive activity continued at Sangay during 17-24 September and the seismic network recorded 244-473 daily explosions. Gas-and-ash plumes visible in webcam and/or satellite images on most days rose 0.6-1.2 km above the summit and drifted mainly W, WSW, and SW. Weather conditions often obscured views. Several daily episodes of crater incandescence were observed during dark hours and incandescent material descended the SE drainage as far as 1.8 km. Incandescent material was ejected 500 m above the summit during 22-23 September. Secretaría de Gestión de Riesgos (SGR) maintained the Alert Level at Yellow (the second highest level on a four-color scale).

Geological Summary. 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 the open 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 eroded by heavy rains into steep-walled canyons up to 600 m deep. The earliest report of an eruption was in 1628. Almost 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.

Sources: Instituto Geofísico-Escuela Politécnica Nacional (IG-EPN), Secretaría de Gestión de Riesgos (SGR)