Report on Nevado del Ruiz (Colombia) — March 1989
Scientific Event Alert Network Bulletin, vol. 14, no. 3 (March 1989)
Managing Editor: Lindsay McClelland.
Nevado del Ruiz (Colombia) Small ash emissions; seismic energy release decreases
Please cite this report as:
Global Volcanism Program, 1989. Report on Nevado del Ruiz (Colombia). In: McClelland, L. (ed.), Scientific Event Alert Network Bulletin, 14:3. Smithsonian Institution. https://doi.org/10.5479/si.GVP.SEAN198903-351020.
Nevado del Ruiz
4.892°N, 75.324°W; summit elev. 5279 m
All times are local (unless otherwise noted)
Seismic energy and the number of high-frequency events decreased during March continuing a general long-term decline. Short pulses (averaging 5 minutes) of low-energy tremor with periods of ~0.25-0.30 seconds were associated with small ash emissions. Dry and electronic tilt and short leveling vectors showed little change. SO2 emissions measured by COSPEC varied from 900 to 4,500 t/d with a monthly average of 1,921 t/d (see figure 26). Emissions were blown SE.
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.