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Report on Nevados de Chillan (Chile) — 24 June-30 June 2020

Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 24 June-30 June 2020
Managing Editor: Sally Kuhn Sennert

Please cite this report as:

Global Volcanism Program, 2020. Report on Nevados de Chillan (Chile). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 24 June-30 June 2020. Smithsonian Institution and US Geological Survey.

Volcano Profile |  Weekly Report (24 June-30 June 2020)


Nevados de Chillan

Chile

36.868°S, 71.378°W; summit elev. 3180 m

All times are local (unless otherwise noted)


SERNAGEOMIN reported an increase in the rate of inflation in the vicinity of Nevados de Chillán’s Nicanor Crater beginning on 20 June. The lava dome in the crater that was visible in satellite images on 11 June (but described in previous reports) had increased in volume based on analysis of 23 June images, and lengthened on the E side. The estimated growth rate of 0.1-0.3 cubic meters per second is two orders of magnitude greater than growth of the Gil-Cruz dome measured during December 2018-early 2019 and one order of magnitude greater that dome growth during August-December 2019. Occasional explosions continued to be recorded, with emissions rising to low heights, and nighttime crater incandescence was visible. The Alert Level remained at Yellow, the second lowest level on a four-color scale, and residents were reminded not to approach the crater within 3 km. ONEMI stated that the Alert Level Yellow (the middle level on a three-color scale) remained in place for the communities of Pinto and Coihueco, and that the public should stay at least 2 km away from the crater.

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.

Sources: Servicio Nacional de Geología y Minería (SERNAGEOMIN), Oficina Nacional de Emergencia-Ministerio del Interior (ONEMI)