IG described the ongoing eruption at Reventador as moderate during 18-25 October. Daily seismicity was characterized by 9-45 explosions, 2-67 long-period earthquakes, 4-25 signals that indicated emissions, and during 20-25 October there were 2-6 periods of harmonic tremor. Gas, steam, and ash plumes, observed almost daily with webcams or reported by the Washington VAAC, rose as high as 1.3 km above the summit and drifted SW, W, and NW. Weather clouds sometimes prevented visual observations. Crater incandescence was occasionally visible and the lava flow on the NE flank was active. Sulfur dioxide emissions averaged 52-83 tons per day during 19-23 October.

Geological Summary. Volcán El Reventador is the most frequently active of a chain of Ecuadorian volcanoes in the Cordillera Real, well east of the principal volcanic axis. The forested, dominantly andesitic stratovolcano has 4-km-wide avalanche scarp open to the E formed by edifice collapse. A young, unvegetated, cone rises from the amphitheater floor to a height comparable to the rim. It has been the source of numerous lava flows as well as explosive eruptions visible from Quito, about 90 km ESE. Frequent lahars in this region of heavy rainfall have left extensive deposits on the scarp slope. The largest recorded eruption took place in 2002, producing a 17-km-high eruption column, pyroclastic flows that traveled up to 8 km, and lava flows from summit and flank vents.

Source: Instituto Geofísico-Escuela Politécnica Nacional (IG-EPN)