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Report on Copahue (Chile-Argentina) — May 2022


Copahue

Bulletin of the Global Volcanism Network, vol. 47, no. 5 (May 2022)
Managing Editor: Edward Venzke. Edited by Kadie L. Bennis.

Copahue (Chile-Argentina) Two thermal anomalies during November 2021

Please cite this report as:

Global Volcanism Program, 2022. Report on Copahue (Chile-Argentina) (Bennis, K.L., and Venzke, E., eds.). Bulletin of the Global Volcanism Network, 47:5. Smithsonian Institution.



Copahue

Chile-Argentina

37.856°S, 71.183°W; summit elev. 2953 m

All times are local (unless otherwise noted)


Copahue is located along the Chile-Argentina border and contains an eastern summit crater with an acidic 300-m-wide crater lake that has exhibited fumarolic activity. The current eruption period began in July 2021 and has been characterized by ash plumes, frequent sulfur dioxide emissions, seismicity, and gas-and-steam emissions (BGVN 46:11). Weak thermal anomalies were also detected. This report covers activity from November 2021 through April 2022, which describes the end of the last eruption period with two thermal anomalies in early November. Information primarily comes from the Servicio Nacional de Geología y Minería (SERNAGEOMIN) Observatorio Volcanológico de Los Andes del Sur (OVDAS) and various satellite data.

Activity was relatively low during November 2021 and consisted of 19 volcano-tectonic (VT) type events and two long-period (LP) events. Gas-and-steam emissions rose less than 1.2 km above the summit. Two weak thermal anomalies were detected in the summit crater on 1 and 6 November 2021, according to Sentinel-2 infrared satellite images (figure 68). No further thermal activity was detected after 6 November through April 2022. Sulfur dioxide data obtained using Differential Absorption Optical Spectroscopy (DOAS) showed an average value of 486 ± 68 tons/day (t/d) and a maximum value of 1,850 t/d on 4 November.

Figure (see Caption) Figure 68. Sentinel-2 infrared satellite images showed a small thermal anomaly in the Copahue summit crater on 1 (left) and 6 (right) November 2021. Images using “Atmospheric penetration” rendering (bands 12, 11, 8a). Courtesy of Sentinel Hub Playground.

During December 2021 through April 2022, seismic activity consisted of 136 VT-type, seven LP-type, and one tremor type (TR) events. Gas-and-steam emissions rose 300-320 m high. Thermal anomalies were no longer observed in satellite imagery. Sulfur dioxide emissions ranged from 213-415 t/d, with a daily maximum value of 1,634 t/d on 28 March.

Geological Summary. Volcán Copahue is an elongated composite cone constructed along the Chile-Argentina border within the 6.5 x 8.5 km wide Trapa-Trapa caldera that formed between 0.6 and 0.4 million years ago near the NW margin of the 20 x 15 km Pliocene Caviahue (Del Agrio) caldera. The eastern summit crater, part of a 2-km-long, ENE-WSW line of nine craters, contains a briny, acidic 300-m-wide crater lake (also referred to as El Agrio or Del Agrio) and displays intense fumarolic activity. Acidic hot springs occur below the eastern outlet of the crater lake, contributing to the acidity of the Río Agrio, and another geothermal zone is located within Caviahue caldera about 7 km NE of the summit. Infrequent mild-to-moderate explosive eruptions have been recorded since the 18th century. Twentieth-century eruptions from the crater lake have ejected pyroclastic rocks and chilled liquid sulfur fragments.

Information Contacts: Servicio Nacional de Geología y Minería (SERNAGEOMIN), Observatorio Volcanológico de Los Andes del Sur (OVDAS), Avda Sta María No. 0104, Santiago, Chile (URL: http://www.sernageomin.cl/, https://twitter.com/Sernageomin); Sentinel Hub Playground (URL: https://www.sentinel-hub.com/explore/sentinel-playground).