Report on Nevado del Ruiz (Colombia) — 7 October-13 October 2015
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 7 October-13 October 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, 7 October-13 October 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 y Sismológico de Manizales reported that during 6-12 October seismicity at Nevado del Ruiz was characterized by long-period earthquakes and short-duration volcanic tremor associated with gas-and-ash emissions. Earthquakes occurred at depths between 1.4 and 8.2 km. The largest event was recorded at 0802 on 11 October, with a local M 3.4, near Arenas Crater at a depth of 3.6 km. That event was felt by residents and corresponded to a seismic increase at the NE part of Arenas Crater. Thermal anomalies over the crater were detected in satellite images during 7 and 9-10 October. Significant amounts of water vapor and gas rose from the crater during the week. A gas, steam, and ash plume rose 1.7 km and drifted NW on 8 October. The Alert Level remained at III (Yellow; "changes in the behavior of volcanic activity").
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.