Report on Nevado del Ruiz (Colombia) — 22 July-28 July 2015
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 22 July-28 July 2015
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2015. Report on Nevado del Ruiz (Colombia). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 22 July-28 July 2015. 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)
Servicio Geológico Colombiano’s (SGC) Observatorio Vulcanológico and Sismológico de Manizales reported increased tremor at Nevado del Ruiz during the morning of 26 July. The webcam recorded an ash plume at 0830 that rose 3 km and drifted NW to SW; ashfall was reported in areas downwind including the municipalities of Chinchiná, Palestina, Santa Rosa de Cabal, Dosquebradas, and Pereira. Later than day seismicity decreased and the webcam showed gas-and-steam emissions that rose 300 m.
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.