Report on Nevados de Chillan (Chile) — 27 January-2 February 2016
Smithsonian / US Geological Survey Weekly Volcanic Activity Report,
27 January-2 February 2016
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2016. Report on Nevados de Chillan (Chile). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 27 January-2 February 2016. Smithsonian Institution and US Geological Survey.
Nevados de Chillan
36.868°S, 71.378°W; summit elev. 3180 m
All times are local (unless otherwise noted)
Servicio Nacional de Geología and Minería (SERNAGEOMIN) Observatorio Volcanológico de Los Andes del Sur (OVDAS) reported that at 1425 on 29 January a phreatic explosion at Nevados de Chillán's Volcán Arrau dome complex generated an ash emission that was associated with a seismic tremor signal. During an overflight on 30 January volcanologists observed that the series of recent phreatic explosions had formed a new crater about 50 m from Arrau Crater, on the E flank. The new crater was 25-30 m wide and at a similar elevation as the crater formed on 8 January. The Alert Level remained at Yellow, the middle level on a three-color scale.
Geological Summary. The compound volcano of Nevados de Chillán is one of the most active of the Central Andes. Three late-Pleistocene to Holocene stratovolcanoes were constructed along a NNW-SSE line within three nested Pleistocene calderas, which produced ignimbrite sheets extending more than 100 km into the Central Depression of Chile. The dominantly andesitic Cerro Blanco (Volcán Nevado) stratovolcano is located at the NW end of the massif. Volcán Viejo (Volcán Chillán), which was the main active vent during the 17th-19th centuries, occupies the SE end. The Volcán Nuevo lava-dome complex formed during 1906-1945 on the NW flank of Viejo. The Volcán Arrau dome complex was then constructed on the SE side of Volcán Nuevo between 1973 and 1986, and eventually exceeded its height. Smaller domes or cones are present in the 5-km valley between the two major edifices.
Source: Servicio Nacional de Geología y Minería (SERNAGEOMIN)