IG reported a high level of activity at Sangay during 17-24 January, which included daily explosions, long-period earthquakes, and gas, steam, and ash emissions. The daily count of explosions ranged from 53-122, though seismic data transmission was sometimes interrupted. Almost daily gas, steam, and ash plumes were either observed in IG webcam images or described in Washington VAAC volcanic activity notifications; weather clouds often prevented observations of the summit. The plumes rose as high as 1.5 km above the volcano and drifted in multiple directions. Multiple thermal anomalies were identified in satellite images on most days. Crater incandescence from the crater and from material on the SE flank was visible at night during 21-22 January. Servicio Nacional de Gestión de Riesgos y Emergencias (SNGRE) maintained the Alert Level at Yellow (the second lowest 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), Servicio Nacional de Gestión de Riesgos y Emergencias (SNGRE)