Report on Nevado del Ruiz (Colombia) — 25 April-1 May 2012
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 25 April-1 May 2012
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2012. Report on Nevado del Ruiz (Colombia). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 25 April-1 May 2012. Smithsonian Institution and US Geological Survey.
Nevado del Ruiz
4.892°N, 75.324°W; summit elev. 5279 m
All times are local (unless otherwise noted)
According to INGEOMINAS, the Observatorio Vulcanológico and Sismológico de Manizales reported that during 25-26 and 28-30 April video data and observers in the city of Manizales (25 km NW) indicated that gas-and-steam plumes rose 0.5-2 km above Nevado del Ruiz's crater. Cloud cover prevented observations on 27 April. Seismic signals indicated that an ash plume was emitted at 1248 on 30 April however cloud cover prevented observations. Seismicity fluctuated, but decreased. The Alert Level remained at II (Orange; "eruption likely within days or weeks").
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.