Report on Nevado del Ruiz (Colombia) — November 1990
Bulletin of the Global Volcanism Network, vol. 15, no. 11 (November 1990)
Managing Editor: Lindsay McClelland.
Nevado del Ruiz (Colombia) Minor ash emission; seismicity; SO2 flux declines
Please cite this report as:
Global Volcanism Program, 1990. Report on Nevado del Ruiz (Colombia) (McClelland, L., ed.). Bulletin of the Global Volcanism Network, 15:11. Smithsonian Institution.
Nevado del Ruiz
4.892°N, 75.324°W; summit elev. 5279 m
All times are local (unless otherwise noted)
Many small ash emissions occurred and high-frequency seismicity was at high levels during November. Hypocenters were located around the crater at shallow depths. Pulses of tremor occurred frequently, often associated with the ash emissions. Low-frequency seismicity was at low levels and there was no measured ground deformation. The SO2 flux continued to decrease, averaging 860 t/d.
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.