Report on Planchon-Peteroa (Chile) — 29 June-5 July 2016
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 29 June-5 July 2016
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2016. Report on Planchon-Peteroa (Chile). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 29 June-5 July 2016. Smithsonian Institution and US Geological Survey.
35.223°S, 70.568°W; summit elev. 3977 m
All times are local (unless otherwise noted)
Based on Observatorio Volcanológico de los Andes del Sur (OVDAS) observations, on 1 July SERNAGEOMIN reported that seismicity at Planchón-Peteroa had begun increasing above baseline levels on 16 June; during 16-30 June the seismic network detected 944 volcano-tectonic events and 1,635 long-period events. The Alert Level was raised to Yellow.
Geologic Background. Planchón-Peteroa is an elongated complex volcano along the Chile-Argentina border with several overlapping calderas. Activity began in the Pleistocene with construction of the basaltic-andesite to dacitic Volcán Azufre, followed by formation of basaltic and basaltic-andesite Volcán Planchón, 6 km to the north. About 11,500 years ago, much of Azufre and part of Planchón collapsed, forming the massive Río Teno debris avalanche, which traveled 95 km to reach Chile's Central Valley. Subsequently, Volcán Planchón II was formed. The youngest volcano, andesitic and basaltic-andesite Volcán Peteroa, consists of scattered vents between Azufre and Planchón. Peteroa has been active into historical time and contains a small steaming crater lake. Historical eruptions from the complex have been dominantly explosive, although lava flows were erupted in 1837 and 1937.