Increased activity at Villarrica volcano, Alert Level raised to Yellow, Chile
The Alert Level for Villarrica volcano, Chile has been raised from Green to Yellow on November 8, 2022. The decision was made due to increased activity detected at the volcano over the past 30 days. The current eruptive episode began in December 2014.
On October 3, SERNAGEOMIN reported that recent passive emissions from Villarrica contained tephra that was deposited on the upper SW flank. Evidence suggested that there were recent fluctuations in the intensity of activity at the lava lake in the main crater.1
The activity increased on October 10, with a thermal anomaly identified in satellite imagery — the most intense anomaly since January 2021.
The most intense thermal anomaly over the crater since September 2019 was detected in satellite images on October 23, and crater incandescence was visible in webcam images. That same day tourists described seeing splashes of lava ejected up to 80 m (260 feet) and hearing loud degassing sounds.
Deposits of ejected tephra were visible around the crater rim and on the upper flanks on October 24, and intense crater incandescence was visible in images on October 25.
On October 25, SERNAGEOMIN reported that the activity at Villarrica had been gradually increasing, with both the number and amplitude of long-period earthquakes increasing during the month. Continuous tremor increased slightly while crater incandescence increased in both frequency and intensity.
Proyecto Observación Villarrica Internet (P.O.V.I.) reported that Strombolian explosions at the volcano intensified on October 31 and ejected material onto the upper flanks. A lava fountain rising above the crater rim was visible on November 1.
During the month of October, 4 eruptive columns were recorded that exceeded 400 m (1 300 feet) in height above the crater. The largest occurred on October 16 and reached 460 m (1 500 feet) in height. This one had a white coloration associated with degassing and correlates with increases in RSAM.2
Pyroclastic flows were registered on October 2, 18, 23 and 31. Deposits were generated close to the crater (< 500 m / 1 640 feet), on the east, south and southwest flanks.
Notable nighttime strombolian explosions were recorded on October 18 and 31. The night glows intensified during the month, with heights less than 200 m (650 feet) above the crater.
As a result of increased activity at the volcano, the Alert Level was raised from Green to Yellow on November 8. The potential impact zone is considered within a radius of 500 m (1 640 feet) from the center of the active crater.
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 (3.7 miles) caldera formed during the late Pleistocene. A 2-km-wide (1.24 miles) caldera that formed about 3 500 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 (12.4 miles) from the volcano were produced during the Holocene.
Lava flows up to 18 km (11.2 miles) 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 (15.4 mi2) of the volcano, and lahars have damaged towns on its flanks.3
References:
1 Weekly Reports published by Global Volcanism Program in October 2022
2 Reporte de Actividad Volcánica (RAV) N°10 Octubre de 2022 – SERNAGEOMIN – November 8, 2022
3 Villarrica – Geological summary – GVP
Featured image credit: P.O.V.I.
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