In a special report issued on 10 June IG-EPN reported that the number and amplitude of explosions at Reventador had increased beginning on 21 March and remained elevated, based on seismic data. Additionally, during this period a slight increase in sulfur dioxide emissions was identified in satellite data. The daily explosion count peaked on 26 May and again on 9 June. IG noted that the characteristics of the ash emissions had not changed and remained at normal levels with plumes typically rising 1 km above the crater rim; plumes to 1.6 km indicate higher activity, and 2 km is considered notable. Since 2 May morphological changes in the crater area reflected the generation of small pyroclastic flows that descended the S and SE flanks but did not impact residents or infrastructure. Explosive activity during 2-3 June created a small ravine on the SSE flank and a 125-m-wide depression at the crater rim, at the head of the ravine. Incandescence at the SE part of the crater became visible and persisted. Subsequent pyroclastic flows were channeled down the ravine, reaching the base of the cone.

During 1-6 June the Washington VAAC issued 584 reports of ash emissions, or an average of two reports per day, according to IG. The plumes rose 400-2,800 m above the crater rim, averaging 1 km high. There were 62-85 daily explosions during 7-11 June. Weather clouds prevented views during 7-9 June. Ash plumes during 10-11 June rose 700-800 m and drifted WNW and NW.

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)