Report on Reventador (Ecuador) — 27 November-3 December 2002
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 27 November-3 December 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, 27 November-3 December 2002. Smithsonian Institution and US Geological Survey.
0.077°S, 77.656°W; summit elev. 3562 m
All times are local (unless otherwise noted)
During 26 November- 1 December, Reventador mainly emitted gas and steam and occasionally small amounts of ash, and seismicity was low. IG stressed to the public that the sulfuric odor in the city of Quito was not indicative of renewed volcanism. During a flight over the volcano on 27 November, IG scientists determined that reports of a second lava flow made the previous week were false; rather, a pyroclastic flow had descended the volcano's NE flank. They also confirmed that a lava flow on the volcano's E flank had been emitted from a small crater that opened ~600 m below the volcano's summit. They believe it began to flow on 24 November and was accompanied by the emission of ash and incandescent rocks. On 2 December incandescence was visible on the E flank of the cone, which was thought to be from a new pulse of lava emitted from the 24 November flow the night of 1 December. On 2 December mudflows traveled down the Montana River, causing problems at a highway.
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.