OVDAS-SERNAGEOMIN reported that the web camera near Copahue recorded white gas plumes rising 250-1,300 m above the crater during 15-18 January and drifting W and NW. Seismicity remained at low levels. The Alert Level was lowered from Orange to Yellow on 18 January.

A seismic swarm of long-period earthquakes started at 1420 on 22 January. The earthquakes were initially deep but became shallower, and volcano-tectonic events were more frequently detected, until the next report posted at 2200. Web camera and satellite images did not show any changes. The Alert Level was raised to Orange.

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.

Source: Servicio Nacional de Geología y Minería (SERNAGEOMIN)