Report on Copahue (Chile-Argentina) — 26 December-1 January 2013
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 26 December-1 January 2013
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2012. Report on Copahue (Chile-Argentina). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 26 December-1 January 2013. Smithsonian Institution and US Geological Survey.
37.856°S, 71.183°W; summit elev. 2953 m
All times are local (unless otherwise noted)
OVDAS-SERNAGEOMIN reported that during 25-29 December white plumes observed with a web camera installed near Copahue rose 450-850 m and drifted NE and E. Plumes detected in satellite imagery drifting 16 km NE on 26 December. Incandescence from the crater was observed at night during 26-28 December; explosions were detected during 27-28 December. Seismicity had decreased during the reporting period. The Alert Level was lowered to Yellow on 29 December.
Geologic Background. 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.