Report on Nevado del Ruiz (Colombia) — April 1990
Bulletin of the Global Volcanism Network, vol. 15, no. 4 (April 1990)
Managing Editor: Lindsay McClelland.
Nevado del Ruiz (Colombia) Seismicity remains low-moderate; glacial ablation significant
Please cite this report as:
Global Volcanism Program, 1990. Report on Nevado del Ruiz (Colombia) (McClelland, L., ed.). Bulletin of the Global Volcanism Network, 15:4. Smithsonian Institution. https://doi.org/10.5479/si.GVP.BGVN199004-351020.
Nevado del Ruiz
4.892°N, 75.324°W; summit elev. 5279 m
All times are local (unless otherwise noted)
Seismic energy release and the number of earthquakes were at low to moderate levels in April. Seismicity peaked on 11 April with 162 low-frequency events. Earthquakes were dispersed around the crater, with focal depths of 0.5-6.5 km. Pulses of low-energy tremor began 26 April and persisted until the 29th, when an episode of continuous low-energy tremor was associated with a small ash emission. Dry and electronic tilt showed no substantial changes. Measurements of glacial behavior showed significant ablation, reaching a rate of the order of 240 m3/day. The average rate of SO2 emission, measured by COSPEC, was 1,467 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.