Report on Nevado del Ruiz (Colombia) — May 1994
Bulletin of the Global Volcanism Network, vol. 19, no. 5 (May 1994)
Managing Editor: Richard Wunderman.
Nevado del Ruiz (Colombia) Earthquake swarms in March and April end two years of low activity
Please cite this report as:
Global Volcanism Program, 1994. Report on Nevado del Ruiz (Colombia) (Wunderman, R., ed.). Bulletin of the Global Volcanism Network, 19:5. Smithsonian Institution. https://doi.org/10.5479/si.GVP.BGVN199405-351020.
Nevado del Ruiz
4.892°N, 75.324°W; summit elev. 5279 m
All times are local (unless otherwise noted)
A high-frequency earthquake swarm in mid-March and early April ended nearly two years of low activity. Significant long-period earthquakes began in mid-April. Several swarms on 19, 22, and 23 April culminated in an explosion at 1554 on the 23rd. Seismic activity gradually declined after the explosion. The Emergency Committee of Caldas declared a yellow alert and suspended visitor and tourist passes until the seismicity had decreased to acceptable levels. [INGEOMINAS stated that there was no emission of ash at the time of the 23 April earthquake swarm.]
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: INGEOMINAS, Manizales; U.S. Embassy, Bogota.