Report on Villarrica (Chile) — 29 November-5 December 2017
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 29 November-5 December 2017
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2017. Report on Villarrica (Chile). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 29 November-5 December 2017. Smithsonian Institution and US Geological Survey.
39.42°S, 71.93°W; summit elev. 2847 m
All times are local (unless otherwise noted)
Gradually increasing activity at Villarrica since 15 November prompted OVDAS-SERNAGEOMIN to raise the Alert Level to Yellow (the second lowest level on a four-color scale) on 5 December, and warn the public to stay outside of a 1-km radius around the crater. Increased activity was characterized by recorded volcano-tectonic earthquakes, increased thermal anomalies identified in satellite data, and increased lava-lake activity. The infrasound network, photos, and field observations confirmed a higher lake level and explosions that were ejecting material deposited in the crater area. Lava fountains 150 m high were documented by POVI during the second half of November.
Geologic Background. Glacier-clad Villarrica, one of Chile's most active volcanoes, rises above the lake and town of the same name. It is the westernmost of three large stratovolcanoes that trend perpendicular to the Andean chain. A 6-km-wide caldera formed during the late Pleistocene. A 2-km-wide caldera that formed about 3500 years ago is located at the base of the presently active, dominantly basaltic to basaltic-andesitic cone at the NW margin of the Pleistocene caldera. More than 30 scoria cones and fissure vents dot the flanks. Plinian eruptions and pyroclastic flows that have extended up to 20 km from the volcano were produced during the Holocene. Lava flows up to 18 km long have issued from summit and flank vents. Historical eruptions, documented since 1558, have consisted largely of mild-to-moderate explosive activity with occasional lava effusion. Glaciers cover 40 km2 of the volcano, and lahars have damaged towns on its flanks.