IG-EPN reported a high level of eruptive activity at Sangay during 1-9 January, with seismic stations recording 173-583 daily explosions. Ash-and-gas plumes were visible, in both webcam and satellite images, rising as high as 1.5 km above the crater rim and drifting SW during 1-5 January. Webcam images showed incandescence at the summit vent and incandescent material descending the SE flank as far as 1.8 km from the crater. Beginning at 1536 on 6 January a series of explosions and ash emissions were visible in webcam images with ash-and-gas plumes rising 3 km above the summit and drifting NW. The activity continued into the late afternoon and intensified; ash plumes rose as high as 8 km above the summit and drifted W, NW, and N. Ashfall was reported in several towns downwind, including San Antonio, Pancún, Cebadas (35 km WNW), Gualiñag, Guargallá Chico, Guamote (40 km WNW), Pungalá (25 km NW), and Chunchi (73 km SW) in the province of Chimborazo, Chillanes (80 km W) in the province of Bolívar, Montalvo (106 km WNW), Babahoyo (135 km WNW), Ventanas, Pueblo Viejo (141 km NW), Vinces (165 km WNW), and Baba (152 km WNW) in the province of El Oro, and Palestina (185 km WNW) in the province of Guayas. Several pyroclastic flows descended the SE drainage during 6-7 January. Ash-and-gas plumes rose 400-800 m above the summit during 7-8 January. During the morning of 8 January, a pyroclastic flow descended the SE drainage and minor ashfall was reported in the Guamote-Chimborazo canton. Cloudy weather prevented views during 8-9 January, though crater incandescence was observed overnight. Secretaría de Gestión de Riesgos 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), Servicio Nacional de Gestión de Riesgos y Emergencias (SNGRE)