Galeras, Colombia

By ExploreNow Editor, on March 7th, 2012

Volcano Type:     Complex volcano
Volcano Status:   Historical
Last Known Eruption:    2010 (continuing)
Summit Elevation:    4276 m    14,029 feet
Latitude:    1.22°N    1°13’0″N
Longitude:    77.37°W    77°22’0″W

Galeras, a stratovolcano with a large breached caldera located immediately west of the city of Pasto, is one of Colombia’s most frequently active volcanoes. The dominantly andesitic Galeras volcanic complex has been active for more than 1 million years, and two major caldera collapse eruptions took place during the late Pleistocene. Long-term extensive hydrothermal alteration has affected the volcano. This has contributed to large-scale edifice collapse that has occurred on at least three occasions, producing debris avalanches that swept to the west and left a large horseshoe-shaped caldera inside which the modern cone has been constructed. Major explosive eruptions since the mid Holocene have produced widespread tephra deposits and pyroclastic flows that swept all but the southern flanks. A central cone slightly lower than the caldera rim has been the site of numerous small-to-moderate historical eruptions since the time of the Spanish conquistadors.

Aerial view of Mount Galeras

Galeras, a 4270-m high andesitic stratovolcano in the southwestern Colombia near the border to Ecuador, gradually awakened again in 1988 after more than 40 years of sleep. Galeras is situated at 1°14′N and 77°’22′W, and its active summit raises 150 m up from the 80 m deep and 320 m wide caldera, which is open to the west. The present active crater lies about 6 km west of Pasto, a city with apprx. 300.000 (400.000?) inhabitants. There are also three smaller craters in the caldera. The diameter on the foot of the volcano is 20 kilometers.