IG-EPN reported that an eruption at Reventador was ongoing during 23-30 July. Seismicity was characterized by 61-90 daily explosions, long-period earthquakes, harmonic tremor, and tremor associated with emissions. Weather conditions prevented visual observations during 23-25 July. Several ash-and-gas plumes observed during 26-30 July rose as high as 1.1 km above the crater rim and drifted N. NW, W, and SW. Avalanches of incandescent material traveled 800-900 m down the flanks during 27-29 July. On 28 July a pyroclastic flow descended the flanks as far as 600 m and on 29 July pyroclastic flows descended the SE flank 600-800 m. During 29-30 July ejected incandescent material fell onto the flanks as far as 400 m below the crater rim. 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: Secretaría de Gestión de Riesgos (SGR), Instituto Geofísico-Escuela Politécnica Nacional (IG-EPN)