The IG reported that the number of earthquakes per day from Reventador increased during July and were the greatest on 24 and 25 July. At 1500 on 27 July, continuous seismic tremor was registered and was followed by observations of incandescence around the crater. Thermal anomalies were also identified on satellite imagery. At 1900 explosions produced ash plumes and ejected incandescent material that fell onto and rolled down the flanks. On 28 July, ash plumes drifted NW and W. Ashfall was reported in Olmedo, about 50 km NW. Later that day, ash plumes rose to altitudes of 4-6 km (13,100-19,700 ft) a.s.l. and drifted NW. On 29 July, steam plumes rose from the crater and drifted NW. A sulfur smell was reported at areas around the volcano. A lava flow traveled S.

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)