Report on Nevados de Chillan (Chile) — 14 August-20 August 2019
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 14 August-20 August 2019
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2019. Report on Nevados de Chillan (Chile). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 14 August-20 August 2019. 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)
ONEMI and SERNAGEOMIN reported multiple explosions at Nevados de Chillán’s Nicanor Crater during 14-20 August, each associated with long-period earthquakes. Two explosions on 14 August, at 0000 and 0029, produced gas emissions and ejected incandescent material onto the flanks. An explosion at 1200 on 16 August produced a grayish ash plume that rose 110 m. Another explosion was detected at 1625 on 17 August. A grayish gas plume from an explosion at 1343 on 18 August rose 400 m, and an explosion at 1938 on 20 August ejected incandescent material onto the flanks. The Alert Level remained at Orange, the second highest level on a four-color scale. ONEMI maintained an Alert Level Yellow (the middle level on a three-color scale) for the communities of Pinto, Coihueco, and San Fabián, and stated that the public should stay at least 3 km away from the crater on the SW flank and 5 km away on the ENE flank.
Geologic Background. 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 largest stratovolcano, dominantly andesitic, Cerro Blanco (Volcán Nevado), is located at the NW end of the group. Volcán Viejo (Volcán Chillán), which was the main active vent during the 17th-19th centuries, occupies the SE end. The new Volcán Nuevo lava-dome complex formed between 1906 and 1945 between the two volcanoes and grew to exceed Volcán Viejo in elevation. The Volcán Arrau dome complex was constructed SE of Volcán Nuevo between 1973 and 1986 and eventually exceeded its height.