Report on Reventador (Ecuador) — 20 November-26 November 2002
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 20 November-26 November 2002
Managing Editor: Gari Mayberry
Please cite this report as:
Global Volcanism Program, 2002. Report on Reventador (Ecuador). In: Mayberry, G (ed.), Weekly Volcanic Activity Report, 20 November-26 November 2002. 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 20-25 November seismicity decreased at Reventador in comparison to the previous week and mostly gas-and-steam emissions occurred with little ash content. On 20 and 21 November 16 earthquakes were recorded each day, whereas about 150 earthquakes were recorded on each of the previous days. At this time gas-and-steam plumes reached to 2 km above the volcano and incandescence was sometimes visible within the crater. Lahars traveled down the volcano's flanks into Montana and Marker gorges. There were many reports of a strong scent of sulfur in the city of Quito, caused by the large amount of SO2 being emitted from Reventador (15,000-29,000 tons of SO2 measured by satellite on the 21st). Eruptions on 24 and 25 November produced ash-and-gas clouds that rose ~1 km above the volcano.
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.