IG reported that seismicity at Reventador was high during 5-11 December and indicated multiple explosions almost daily. Plumes were observed although cloud cover often prevented visual observations. On 5 December a steam plume rose 1.5 km and drifted NW. The next day a steam-and-ash plume rose 2 km above the lava dome and drifted SE. A steam-and-ash plume rose 1 km on 8 December and drifted WSW, towards Chaco. Another steam-and-ash plume was observed on 11 December.

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)