Report on Villarrica (Chile) — 23 September-29 September 2020
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 23 September-29 September 2020
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2020. Report on Villarrica (Chile). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 23 September-29 September 2020. Smithsonian Institution and US Geological Survey.
39.42°S, 71.93°W; summit elev. 2847 m
All times are local (unless otherwise noted)
SERNAGEOMIN reported that activity at Villarrica was characterized by an active lava lake, minor explosions, and gas emissions during 1-15 September. Webcam images showed whitish gas emissions rising no higher than 500 m above the crater rim during the day, with occasional nighttime crater incandescence and ejected material seen at night. Satellite images showed tephra deposits around the crater extending from the rim up to 36 m on the E and SE flanks on both 5 and 7 September. Two thermal anomalies were visible in satellite images on 14 September. At 1350 on 25 September the seismic network recorded a long-period earthquake associated with a moderate explosion. The explosion generated an ash plume that rose 800 m above the vent and drifted ENE, and ejected blocks onto the flanks. Another long-period event and explosion were recorded at 1829 later that day that generated another ash plume, though weather clouds obscured views. The Alert Level remained at Yellow, the second lowest level on a four-color scale. ONEMI maintained an Alert Level Yellow (the middle level on a three-color scale) for the municipalities of Villarrica, Pucón (16 km N), Curarrehue, and the commune of Panguipulli, and the exclusion zone for the public of 500 m around the crater.
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.