Report on Cotopaxi (Ecuador) — 18 November-24 November 2015
Smithsonian Institution / US Geological Survey
Weekly Volcanic Activity Report, 18 November-24 November 2015
Managing Editor: Sally Sennert.
Please cite this report as:
Global Volcanism Program, 2015. Report on Cotopaxi (Ecuador) (Sennert, S, ed.). Weekly Volcanic Activity Report, 18 November-24 November 2015. Smithsonian Institution and US Geological Survey.
0.677°S, 78.436°W; summit elev. 5911 m
All times are local (unless otherwise noted)
IG reported that during 18-24 November gas, steam, and ash plumes rose almost daily from Cotopaxi, as high as 1.5 km above the crater, and drifted W, and SW. Ashfall was reported in Machachi and Aloasí on 18 November.
Geological Summary. The symmetrical, glacier-covered, Cotopaxi stratovolcano is Ecuador's most well-known volcano and one of its most active. The steep-sided cone is capped by nested summit craters, the largest of which is about 550 x 800 m in diameter. Deep valleys scoured by lahars radiate from the summit of the andesitic volcano, and large andesitic lava flows extend to its base. The modern edifice has been constructed since a major collapse sometime prior to about 5,000 years ago. Pyroclastic flows (often confused in historical accounts with lava flows) have accompanied many explosive eruptions, and lahars have frequently devastated adjacent valleys. Strong eruptions took place in 1744, 1768, and 1877. Pyroclastic flows descended all sides of the volcano in 1877, and lahars traveled more than 100 km into the Pacific Ocean and western Amazon basin. Smaller eruptions have been frequent since that time.