IG reported that the eruption at Sangay that began on 8 August ended on 7 December after about four months of activity. The eruption was characterized by the extrusion of lava flows, and ash emissions that rose between 0.5-1.4 km (and occasionally higher than 2 km) and mainly drifted W and NW. Minor amounts of ash fell in Guayaquil on 18 September. Lava flows traveled 1-2 km down the ESE flank, and both block avalanches and possible small pyroclastic flows from the flow fronts traveled additionally as far as 7 km.

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)