Report on Copahue (Chile-Argentina) — 6 July-12 July 2016
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 6 July-12 July 2016
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2016. Report on Copahue (Chile-Argentina). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 6 July-12 July 2016. 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 16-30 June the eruption at Copahue was characterized by phreato-magmatic explosions and Strombolian activity. On 4 July, SERNAGEOMIN posted on their social media page photos from an overflight showing Strombolian activity from a crater atop of a pyroclastic cone which was forming on the floor of El Agrio crater. Based on webcam and satellite views, the Buenos Aires VAAC reported that during 7-8 July diffuse gas-and-steam plumes with minor amounts of ash rose to an altitude of 3 km (10,000 ft) a.s.l. and drifted E and SE. The Alert Level remained at Yellow; SERNAGEOMIN recommended no entry into a restricted area within 1.5 km of the crater.
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.