Report on Villarrica (Chile) — 18 July-24 July 2018
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 18 July-24 July 2018
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2018. Report on Villarrica (Chile). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 18 July-24 July 2018. Smithsonian Institution and US Geological Survey.
39.42°S, 71.93°W; summit elev. 2847 m
All times are local (unless otherwise noted)
POVI reported that sometime during mid-morning on 18 July webcam images captured two vapor-and-gas emissions with some ash rising from Villarrica. Between 1100 and 1200 that same day a thermal anomaly (the largest since December 2017) was identified in satellite images. Crater incandescence was visible later that day. An earthquake, possibly a volcano-tectonic signal, was detected at about 0627 on 20 July, a few hours after gas-and-steam emissions decreased. Crater incandescence was visible on 23 July.
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.