Based on analysis of satellite imagery, the Washington VAAC reported a possible ash emission from Reventador on 11 August. The next day a well-defined thermal anomaly was detected and an ash plume drifted W. According to the VAAC, IG confirmed the ash plume, noting that it rose to an altitude of 5.2 km (17,000 ft) a.s.l.

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: Washington Volcanic Ash Advisory Center (VAAC)