IG reported that for the past year, activity at Sangay is centered at two summit vents: the Central Crater which produced ash-and-gas emissions and the Ñuñurcu dome (located 190 m SSE of Central Crater) which effused lava. Lava, pyroclastic flows, and collapsed material were channeled down the Volcán River drainage on the SE flank. Activity at Sangay intensified during 8-9 June with lava-flow collapses, pyroclastic flows on the SE flank that reached the Upano River, and significant ash emissions that drifted W. No variation in seismic data was noted prior to a period of increased activity. A comparison of webcam images from 2 September 2019 and 10 June 2020 showed that the drainage had widened, deepened, and lengthened.

In recent weeks ash plumes had risen as high as 2.9 km above the crater rim and had been carried farther by strong winds. Ashfall was reported in the provinces of Chimborazo, Bolívar, Guayas, Santa Elena, Los Ríos, and Morona Santiago. Activity slightly increased during 11-12 June, characterized by ash-and-gas plumes rising higher (1.5-2.8 km above the crater rim) and drifting farther (over 600 km W and SW), and an increased number of thermal anomalies on the SE flank from intensified lava effusion. A pulse of increased seismic activity was also detected. Ashfall was additionally reported in the provinces of Tungurahua and Cotopaxi.

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)