Report on Villarrica (Chile) — 2 November-8 November 2022
Smithsonian / US Geological Survey Weekly Volcanic Activity Report,
2 November-8 November 2022
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2022. Report on Villarrica (Chile). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 2 November-8 November 2022. Smithsonian Institution and US Geological Survey.
39.42°S, 71.93°W; summit elev. 2847 m
All times are local (unless otherwise noted)
SERNAGEOMIN and Observatorio Argentino de Vigilancia Volcánica (OAVV) reported that activity at Villarrica increased during 1 October-7 November. Seismic signals indicated above-baseline activity, including intensifying continuous tremor and an increase in the number of long-period earthquakes. The largest earthquake was a M 2.3 event located 5.3 km ESE of the crater at a depth of 4.8 km. Acoustic data indicated that explosions became larger. Sulfur dioxide emissions recorded on two stations, 10 km ENE and 6 km ESE, averaged around 541 tons per day, with a maximum value of 1,273 tons per day on 13 October; the values were within normal ranges, though they were preceded by two months with high values. Sulfur dioxide emissions were identified in satellite images on 1 November.
The lava lake occupied an area of about 36 square meters on the crater floor based on a 14 October satellite image. During October webcam images showed eruption plumes rising as high as 460 m above the crater rim. Plumes deposited tephra on the E, S, and SW flanks within 500 m of the crater on 2, 18, 23, and 31 October. Nighttime crater incandescence seen in webcam images intensified during 1 October-7 November, and strombolian explosions ejected incandescent tephra onto the NW and SW flanks on 18 and 31 October and during 1, 2, and 6-7 November. Thermal anomalies were identified in satellite images on 2, 10, 15, 22, 27, and 31 October, and 1, 4, and 6 November. POVI reported that the width of lava fountains rising above the crater rim on 2 November suggested that the vent on the crater floor was about 6 m in diameter. Analysis of satellite images and reports from observers indicated that more material was being ejected onto the upper flanks in November, with clasts up to 20 cm in diameter and deposits trending NW. On 8 November SERNAGEOMIN raised the Alert Level to Yellow (the second lowest level on a four-color scale) and warned that material could be ejected within 500 m of the crater. ONEMI declared 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.
Geological Summary. 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.
Sources: Servicio Nacional de Geología y Minería (SERNAGEOMIN), Oficina Nacional de Emergencia-Ministerio del Interior (ONEMI), Proyecto Observación Villarrica Internet (POVI), Servicio Geológico Minero Argentino (SEGEMAR)