IG-EPN reported that a moderate eruption at Reventador was ongoing during 12-19 March. Seismicity was characterized by 23-48 daily explosions, long-period earthquakes, harmonic tremor, and tremor associated with emissions. Ash-and-gas plumes rose as high as 1.3 km above the crater rim and drifted in multiple directions on most days. Weather conditions sometimes prevented views; emissions were not visible during 14-15 March. Avalanches of incandescent material were visible most overnights, descending the flanks as far as 900 m from the summit. Minor crater incandescence was visible during 14-15 March. The weather was occasionally rainy during the week; a seismic signal indicating a lahar was recorded at 0210 on 19 March. 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)