Report on Villarrica (Chile) — 4 September-10 September 2019
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 4 September-10 September 2019
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2019. Report on Villarrica (Chile). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 4 September-10 September 2019. Smithsonian Institution and US Geological Survey.
39.42°S, 71.93°W; summit elev. 2847 m
All times are local (unless otherwise noted)
ONEMI and SERNAGEOMIN reported that the seismic network at Villarrica recorded significant variations in seismicity beginning at 0030 on 8 September, characterized by an increase in the number of long-period (LP) events from 20 to 50 per hour. LP events ceased to be detected around 1030 and short periods of high-energy tremor began. Weather clouds prevented views of the summit crater, though the characteristics of the seismicity indicated fluctuating lava-lake activity. The increased seismicity persisted on 9 September, prompting SERNAGEOMIN to raise the Alert Level to Orange, the second highest level on a four-color scale. ONEMI has maintained an Alert Level Yellow (the middle level on a three-color scale) since 6 August for the municipalities of Villarrica, Pucón (16 km N), and Curarrehue, along with the commune of Panguipulli and stated that the public should stay at least 2 km away from the crater. On 10 September seismicity remained high; infrasound signals were recorded at a rate of 50 events per hour.
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.