Report on Reventador (Ecuador) — 14 October-20 October 2009
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 14 October-20 October 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, 14 October-20 October 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 field observations of Reventador on 16 and 17 September confirmed the presence of a lava flow on the S flank of the cone. Gas and steam emissions were noted, as was growth of the lava dome. Thermal anomalies over the crater area were detected in satellite imagery on 6, 11, and 13 October. On 14 October, seismicity increased and harmonic tremor was detected. A seismic station on the NE flank of the cone detected rockfalls. Several people living in the area reported roaring noises and observed slight incandescence from the crater during the previous few nights.
During an overflight on 16 October, scientists saw the lava dome and a lava flow on the N flank. Bluish gases were emitted. According to a thermal camera, the incandescent parts in the crater were about 300 degrees Celsius. Other observers heard roaring noises and sounds resembling "cannon shots." Incandescent blocks were ejected from the crater, and steam and gases rose 100 m and drifted SW. Incandescent material was seen on the S flank. On 17 October, incandescence on the S flank was seen and noises similar the previous day were again heard. A small gray plume was seen the next day. On 19 October, thermal anomalies were again detected on satellite imagery. During an overflight, blue gas plumes were seen. The lava flow on the S flank occupied a large area and was divided into two branches.
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.