During 30 October through 5 November, IG reported that moderate activity from Reventador continued. Elevated seismicity included explosions (8-35 per day), long period earthquakes, and tremor related to emissions and fluid movement in the crust (harmonic tremor). Plumes of steam were frequently observed when the weather permitted; ash plumes were generated on 31 October, 2 November, and 5 November. Ashfall from these events reached the town of San Rafael on 31 October and 2 November; a pilot observed ash on 2 November at an altitude of 6.7 km (22,000 ft). Observers heard roaring noises and sounds resembling "cannon shots" on 31 October and 1 November.

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), Washington Volcanic Ash Advisory Center (VAAC)