IG reported that in the evening of 8 June, through the next morning, an eruptive event at Sangay was characterized as the collapse of one or more lava-flow fronts. Pyroclastic flows descended the Volcán River on the SE flank, and based on thermal anomalies some reached the Upano River. The Washington VAAC stated that ash plumes drifted SW. Several regional communities downwind reported ashfall including Santa Elena (170 km W), Guayas (175 km W), Los Ríos, Chimborazo, and the Morona-Santiago province. The most significant ashfall occurred in Alausí (60 km WSW). The local seismic station stopped transmitting signals on 7 June, though stations located tens of kilometers N recorded signals from the event beginning around 2000 on 8 June and lasting several hours.

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.

Source: Instituto Geofísico-Escuela Politécnica Nacional (IG-EPN)