Report on Reventador (Ecuador) — 21 June-27 June 2017
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 21 June-27 June 2017
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2017. Report on Reventador (Ecuador). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 21 June-27 June 2017. Smithsonian Institution and US Geological Survey.
0.077°S, 77.656°W; summit elev. 3562 m
All times are local (unless otherwise noted)
IG reported that during the previous months activity at Reventador was characterized by an average of 50 explosions per day and long-period earthquakes indicating fluid movement. Ash plumes from explosions rose as high as 2 km above the crater rim, and small pyroclastic flows descended the flanks in almost all directions. However, at 1701 on 22 June the pattern of activity changed. Seismic signals indicating emissions became continuous, and spasmodic tremor emerged which was composed of numerous small explosions. Concurrent to the change in seismicity, small-to-moderate pyroclastic flows descended 4 km down the NE flank, and plumes with low-to-moderate ash content rose 2.5 km and drifted W. Pyroclastic-flow deposits were also noted in the upper basin of El Reventador river, E of the cone. During 22-23 June incandescent blocks rolled 500 m down the flanks, steam-and-ash plumes rose 2 km, and several pyroclastic flows traveled 900 m NE. Cloud cover sometimes prevented visual observations during 24-27 June though sometimes gas-and-ash plumes were seen rising no higher than 500 m above the crater rim. Incandescent blocks continued to descend the flanks, traveling as far as 650 m. “Cannon shot” sounds were heard at night during 24-25 June. During 26-27 June several episodes of incandescence at the crater were noted, and a lava flow traveled 2 km down the NE flank.
Geologic Background. 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 Volcán El Reventador stratovolcano rises to 3562 m above the jungles of the western Amazon basin. A 4-km-wide caldera widely breached to the east was formed by edifice collapse and is partially filled by a young, unvegetated stratovolcano that rises about 1300 m above the caldera floor to a height comparable to the caldera rim. It has been the source of numerous lava flows as well as explosive eruptions that were visible from Quito in historical time. Frequent lahars in this region of heavy rainfall have constructed a debris plain on the eastern floor of the caldera. The largest historical 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.