Report on Nevado del Ruiz (Colombia) — December 1988
Scientific Event Alert Network Bulletin, vol. 13, no. 12 (December 1988)
Managing Editor: Lindsay McClelland.
Nevado del Ruiz (Colombia) High-frequency seismicity drops; energy release still high
Please cite this report as:
Global Volcanism Program, 1988. Report on Nevado del Ruiz (Colombia) (McClelland, L., ed.). Scientific Event Alert Network Bulletin, 13:12. Smithsonian Institution. https://doi.org/10.5479/si.GVP.SEAN198812-351020.
Nevado del Ruiz
4.892°N, 75.324°W; summit elev. 5279 m
All times are local (unless otherwise noted)
The number and energy release of high-frequency seismic events at Ruiz continued to decline in December, while low-frequency seismicity was similar to previous months (figure 22). Total seismic energy release remained substantially elevated (figure 23). There were two main clusters of high-frequency events, one roughly 4 km E of the crater at ~2.5 km depth, the second 3 km SW of the volcano at ~2 km depth. Brief increases in tremor intensity occurred more often in December, but their energy was low. No significant deformation was measured during the month. The rate of SO2 emission averaged ~1,220 t/d.
|Figure 22. Number of seismic events/month at Ruiz (left) and monthly seismic energy release (right) for high-frequency (top) and low-frequency events (bottom), January-December 1988. Courtesy of INGEOMINAS.|
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.