Report on Nevado del Ruiz (Colombia) — December 1990
Bulletin of the Global Volcanism Network, vol. 15, no. 12 (December 1990)
Managing Editor: Lindsay McClelland.
Nevado del Ruiz (Colombia) Small ash emissions
Please cite this report as:
Global Volcanism Program, 1990. Report on Nevado del Ruiz (Colombia) (McClelland, L., ed.). Bulletin of the Global Volcanism Network, 15:12. Smithsonian Institution.
Nevado del Ruiz
4.892°N, 75.324°W; summit elev. 5279 m
All times are local (unless otherwise noted)
Several ash emissions occurred during December. Seismic activity was characterized by high-frequency earthquakes (figure 43), centered W and SW of the the crater. Tremor was frequent, but of low energy. Ground deformation measurements showed no significant changes. The month's average SO2 flux was 1,464 t/d, up from 860 t/d in November.
|Figure 43. Daily seismic energy release at Ruiz, December 1990. Solid line, high-frequency events; dashed line, low-frequency events. Courtesy of INGEOMINAS.|
Geologic Background. Nevado del Ruiz is a broad, glacier-covered volcano in central Colombia that covers more than 200 km2. 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 caldera of an older edifice. The 1-km-wide, 240-m-deep Arenas crater occupies the summit. The prominent La Olleta pyroclastic cone located on the SW flank may also have been active in historical time. Steep headwalls of massive landslides cut the flanks. 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.
Information Contacts: C. Carvajal, INGEOMINAS, Manizales.