Report on Reventador (Ecuador) — 12 August-18 August 2009
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 12 August-18 August 2009
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2009. Report on Reventador (Ecuador). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 12 August-18 August 2009. Smithsonian Institution and US Geological Survey.
0.077°S, 77.656°W; summit elev. 3562 m
All times are local (unless otherwise noted)
The IG reported that seismic tremor from Reventador was sporadically detected during 21 July-3 August. On 4 August, seismicity increased and periods of tremor frequently saturated the seismic stations. Thermal anomalies detected in satellite imagery on 1 and 2 August became more intense on 4, 5, and 10 August. On 6 August, a steam plume rose 1.2 km above the crater and drifted W. Incandescent blocks were ejected from the crater and fell onto the flanks. Thermal images taken from a location 7 km E of Reventador revealed a linear area of higher temperatures, confirming the presence of a new lava flow on the S flank. Incandescence in the crater was seen during observations on 9 August. According to the Washington VAAC, IG reported that an ash plume rose to an altitude of 3.6 km (11,700 ft) a.s.l. and drifted NW on 15 August.
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.