Report on Nevado del Ruiz (Colombia) — March 1991
Bulletin of the Global Volcanism Network, vol. 16, no. 3 (March 1991)
Managing Editor: Lindsay McClelland.
Nevado del Ruiz (Colombia) Continued gas emission; two seismic swarms; ash to 30 km distance
Please cite this report as:
Global Volcanism Program, 1991. Report on Nevado del Ruiz (Colombia) (McClelland, L., ed.). Bulletin of the Global Volcanism Network, 16:3. Smithsonian Institution. https://doi.org/10.5479/si.GVP.BGVN199103-351020
Nevado del Ruiz
4.892°N, 75.324°W; summit elev. 5279 m
All times are local (unless otherwise noted)
Two high-frequency earthquake swarms were recorded in March, the first centered N of Arenas crater, and the second to the S. The number of events, energy released, and tremor amplitude were all at low levels. No significant changes in deformation were observed. Ashfall was reported up to 30 km WNW (Villamaría), from an emission on 5 March. The monthly average SO2 flux, measured by COSPEC, was 2,233 t/d, an increase from 753 t/d in February and 1,140 t/d in January.
Geological Summary. 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.