The Instituto Geofísico-Escuela Politécnica Nacional (IG-EPN) reported that eruptive activity continued at Reventador during 18-25 February. Seismicity included 36-84 daily explosions, long-period earthquakes, harmonic tremor, and tremor associated with emissions, though the transmission of seismic and webcam data was sometimes interrupted, especially during 21-23 February. Weather conditions on most days were clear enough to observe ash-and-gas plumes in webcam and/or satellite images rising 300-1,100 m above the crater and drifting NW, WNW, W, and SW. Webcams almost nightly recorded multiple instances of incandescent material descending the flanks as far as 1 km below the crater rim. At 1245 on 22 February a small- to moderate-sized, secondary lahar descended the Marker River on the S flank. 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)