Report on Nevados de Chillan (Chile) — 17 January-23 January 2018
Smithsonian Institution / US Geological Survey
Weekly Volcanic Activity Report, 17 January-23 January 2018
Managing Editor: Sally Sennert.
Please cite this report as:
Global Volcanism Program, 2018. Report on Nevados de Chillan (Chile) (Sennert, S, ed.). Weekly Volcanic Activity Report, 17 January-23 January 2018. 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 continuing explosive activity during 1-15 January associated with a low rate of lava-dome growth in the active crater. Gas plumes from the explosions rose less than 1 km above the crater rim, and sporadic incandescence associated with some explosions was recorded at night. The lava-dome growth rate was low at 1,360 m3/day, determined by photos taken during overflights on 9 and 12 January. The total volume of the lava dome was an estimated 37,000 m3. The Alert Level remained at Yellow, the middle level on a three-color scale, and the public was reminded not to approach the craters within a 4-km radius.
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.