Nevado del Ruiz, Colombia

By ExploreNow Editor, on April 26th, 2012%

Nevado del Ruiz

Volcano Type:      Stratovolcano
Volcano Status:    Historical
Last Known Eruption:     1991
Summit Elevation:     5321 m     17,457 feet
Latitude:     4.895°N     4°53’43″N
Longitude:     75.322°W     75°19’21″W

Nevado del Ruiz is a broad, glacier-covered volcano in central Colombia that covers >200 sq km. Three major edifices, composed of andesitic and dacitic lavas and andesitic pyroclastics, have been constructed since the beginning of the Pleistocene. The modern cone consists of a broad cluster of lava domes built within the summit caldera of an older Ruiz volcano. The 1-km-wide, 240-m-deep Arenas crater occupies the summit. The prominent La Olleta pyroclastic cone is located on the SW flank, and may also have been active in historical time. Steep headwalls of massive landslides cut the flanks of Nevado del Ruiz. Melting of its summit icecap during historical eruptions, which date back to the 16th century, has resulted in devastating lahars, including one in 1985 that was South America’s deadliest eruption.

Steam on the mountain in July 2007

Steam on the mountain in July 2007

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Originally posted 2010-08-17 04:25:12.

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Galeras, Colombia

By ExploreNow Editor, on March 7th, 2012%

Galeras

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.
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Originally posted 2010-08-29 04:25:25.

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