IG-EPN reported that an eruption at Reventador was ongoing during 14-21 May. Seismicity was characterized by 46-78 daily explosions, long-period earthquakes, harmonic tremor, volcano-tectonic events, and tremor associated with emissions. Ash-and-gas plumes rose as high as 1.1 km above the crater rim and drifted NW, W, and SW during 14-18 and 21 May. Weather conditions sometimes prevented views, especially during 19-20 May. Incandescence at the crater was visible during most nights and avalanches of incandescent material descended the flanks as far as 500 m from the summit on a few of the nights. Secretaría de Gestión de Riesgos maintained the Alert Level at Orange (the second highest level on a four-color scale).

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.

Sources: Instituto Geofísico-Escuela Politécnica Nacional (IG-EPN), Secretaría de Gestión de Riesgos (SGR)