IG described the ongoing eruption at Reventador as moderate during 9-15 November. Daily seismicity was characterized by 18-47 explosions, 22-45 long-period earthquakes, and 2-18 signals that indicated emissions. During 9-12 November there were also 1-4 periods of daily 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 S, W, SW, N, and NW. Crater incandescence was occasionally visible at night and the lava flow on the NE flank was active. Sulfur dioxide emissions averaged 22, 20.2, and 174.9 tons per day on 9, 11, and 12 November, respectively. An incandescent avalanche was visible on the N flank during the night of 9 November; by 10 November it had traveled to 800 m below the crater.

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 about 1,300 m 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 constructed a debris plain on the eastern floor of the scarp. 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)