Report on Nevado del Ruiz (Colombia) — September 1991
Bulletin of the Global Volcanism Network, vol. 16, no. 9 (September 1991)
Managing Editor: Lindsay McClelland.
Nevado del Ruiz (Colombia) Seismicity and SO2 flux at low levels
Please cite this report as:
Global Volcanism Program, 1991. Report on Nevado del Ruiz (Colombia). In: McClelland, L. (ed.), Bulletin of the Global Volcanism Network, 16:9. Smithsonian Institution. https://doi.org/10.5479/si.GVP.BGVN199109-351020.
Nevado del Ruiz
4.892°N, 75.324°W; summit elev. 5279 m
All times are local (unless otherwise noted)
The number of seismic events and the amount of released energy were both at low levels in September. Only a few short pulses of very low-energy tremor were recorded. Deformation showed no significant changes. The monthly average SO2 flux was low, declining to ~925 t/d from 1,135 t/d in August.
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.