IG reported that the eruption at Sangay continued at a high level, with lava flows effusing from the Ñuñurcu, Central, and Norte vents. Explosions originated from a western vent that reactivated in late 2021, and from Central vent. The Norte vent, on the N flank, had opened on 2 December 2021. Activity levels were slightly higher during 4-6 April, characterized by a higher rate of lava effusion and a satellite-detected thermal anomaly at the Norte vent on 4 April, along with a diffuse but continuously-emitted volcanic cloud that rose 1.7 km above the crater rim and drifted up to 650 km W during 5-6 April. Low-frequency tremor was also recorded during 5-6 April. Even though the eruption plume drifted notably farther than average distances recorded during 2019-2022, only minor ashfall was reported in Chauzán San Alfonso (40 km W, in Guamote canton, Chimborazo province). During 12-18 April weather clouds and rain often prevented visual and webcam observations of the volcano, though daily ash-and-gas plumes were identified in satellite images by the Washington VAAC or in webcam views; plumes rose less than 2 km above the volcano and drifted W and NW. Minor ashfall was reported in Chauzán San Alfonso. The seismic network detected signals indicating descending lahars during 12-13 and 15 April.

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)