IG reported that a high level of activity continued to be recorded at Reventador. In a special report, IG reviewed the activity had started in mid-June, characterized by strong explosions, the ejection of blocks that rolled down the flanks, and pyroclastic flows that descended the N, NE, and W flanks less than 1 km. Additionally, at the beginning of August, a small lava flow effused at the summit and traveled 400-500 m down the NE flank. Formation of a summit lava dome was also noted on 17 August. The number of thermal alerts was the highest in August compared to the rest of the year. The cone destroyed during a 2002 eruption had been rebuilt and was as tall or slightly taller by 11 September.

During 9-15 September gas, steam, and ash emissions observed with the webcam or reported by the Washington VAAC, sometimes multiple times a day, rose as high as 1 km above the summit crater and drifted N, NW, and W. Incandescent blocks rolled down the N flank during 9-10 September and as far as 600 m down the S and SW flanks during 13-15 September. The lava flow on the NE flank had not lengthened.

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)