IG-EPN reported that high levels of eruptive activity continued at Sangay during 23-30 July. The seismic network recorded 1,175-1,840 daily explosions. Daily gas-and-ash plumes were visible in webcam and/or satellite images and rose 500-2,500 m above the summit and drifted mainly NW, W, and SW. Incandescent material at the summit crater was periodically visible during dark hours, and several episodes of incandescent material were visible descending the SE drainage as far as 2 km during 23-28 July; weather conditions often obscured views. On 24 July a pyroclastic flow traveled 2 km down the SE drainage. Minor ashfall was reported in towns in the Chimborazo province including Alausí (60 km SW) and Guarguallá (25 km WNW) during 24-25 July, Alausí during 27-29 July, and Chunchi (73 km SW) on 30 July. 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)