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Report on Reventador (Ecuador) — 20 November-26 November 2002


Reventador

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.

Weekly Report (20 November-26 November 2002)

Reventador

Ecuador

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.

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 about 1,300 m 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 constructed a debris plain on the eastern floor of the scarp. 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.

Sources: Instituto Geofísico-Escuela Politécnica Nacional (IG), Washington Volcanic Ash Advisory Center (VAAC)