IG reported that during 14-21 May seismic data from Reventador’s network indicated a high level of seismic activity, including explosions, long-period earthquakes, harmonic tremor, and signals indicating emissions. Weather conditions often prevented views of the summit area, although when clear (during 17-18 and 20-21 May) several ash plumes were visible rising as high as 1 km above the crater rim and drifting W and NW. Crater incandescence was visible on some mornings and evenings. On 19 May a 500-m-long pyroclastic flow deposit on the N flank was visible. Blocks were observed rolling 800 m down the flanks on 21 May.

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)