IG reported a high level of eruptive activity at Sangay during 27 June-4 July. Seismic stations recorded 311-923 daily explosions. Crater incandescence was visible in late-night webcam images on 28 June and 2-4 July. Gas, steam, and ash plumes were observed in webcam images or described in aviation notices issued by the Washington VAAC based on satellite images, though weather clouds sometimes prevented views. Emissions rose 0.7-2.1 km above the crater rim and drifted SW, W, and NW during 28-30 June and 2-4 July. Explosions ejected incandescent material that traveled down the SW flank as far as 1.8 km below the crater overnight during 3-4 July. 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), Secretaría de Gestión de Riesgos (SGR), Washington Volcanic Ash Advisory Center (VAAC)