On 14 September SERNAGEOMIN reported elevated seismicity from Copahue. A seismic swarm occurred during 1200-1900 comprising 389 LP earthquakes; epicenters were within the crater area and hypocenters were at depths less than 3 km. SERNAGEOMIN noted that this unrest was similar to that from May and October 2013. Web cameras located nearby captured a persistent vapor plume that reached ~250 m above the crater and drifted ~700 m ENE. The Alert Level remained at Yellow.

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)