DESCRIPTION:
Ecuador Volcanoes and Volcanics

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Map, Major Volcanoes of Ecuador

The symmetrical, glacier-clad Cotopaxi stratovolcano (5,911 meters) is Ecuador's most well-known volcano and one of its most active. The steep-sided cone is capped by nested summit craters 650 x 800 meters in diameter. Deep valleys scoured by lahars radiate from the summit and large andesitic lava flows extend as far as the base of Cotopaxi. Lahars accompanying explosive eruptions of Cotopaxi have frequently devastated adjacent valleys. The most violent historical eruptions took place in 1744, 1768, and 1877. Pyroclastic flows descended all sides of the volcano in 1877 and lahars traveled more than 100 kilometers into the Pacific Ocean and western Amazon basin. The last significant eruption took place in 1904.

Guagua Pichincha Volcano
Location: Ecuador, South America
Latitude: 0.171 S
Longitude: 78.598 W
Height: 4,784 meters (15,696 feet)
Type: Stratovolcano

Guagua Pichincha and the older Pleistocene Rucu Pichincha stratovolcanoes rise immediately west of Quito at the west end of the 25-kilometer-long (15-mile-long) volcanic complex. The horseshoe-shaped summit crater, approximately 2 kilometers (1.3 miles) in diameter and 600 meters deep (2,000 feet), was breached to the west during a late-Pleistocene slope failure, approximately 50,000 years ago. Subsequent late-Pleistocene and Holocene eruptions from the central vent consisted of explosive activity with pyroclastic flows accompanied by periodic lava dome growth and destruction. Many minor eruptions have occurred since the Spanish era. The central lava dome was probably emplaced during the volcano's largest historical eruption, in 1660, that dropped 30 centimeters (12 inches) of ash on Quito and generated west-flank pyroclastic flows. The volcano has no permanent ice cap.

Seismic data has been collected intermittently since 1977 and continuously since 1981 by the Instituto de Geofísico, Escuela Politécnica, which installed a 6-station telemetering seismic network in August 1988. Phreatic activity from the northeast flank of the lava dome in 1981 and 1982 ejected a small amount of ash and blocks. A single phreatic explosion occurred from the same area in 1985.

Tungurahua is a steep-sided stratovolcano (5,023 meters) that towers 3 kilometers above its northern base. Historical eruptions have originated from the summit crater and have included strong explosions and sometimes lava flows, lahars, and pyroclastic flows that reached populated areas at the volcano's base. The volcano's complex historical record includes sudden, violent eruptions.

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