Report on Puyehue-Cordon Caulle (Chile) — 18 April-24 April 2012
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 18 April-24 April 2012
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2012. Report on Puyehue-Cordon Caulle (Chile). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 18 April-24 April 2012. Smithsonian Institution and US Geological Survey.
40.59°S, 72.117°W; summit elev. 2236 m
All times are local (unless otherwise noted)
OVDAS-SERNAGEOMIN reported that, although cloud cover often prevented observations during 17-22 April, satellite and web camera views of the Cordón Caulle rift zone, part of the Puyehue-Cordón Caulle volcanic complex, occasionally showed plumes that rose no higher than 400 m above the crater. Incandescence from the crater was observed during 17-18 and 20-21 April. Due to the low level of activity and decreasing seismicity, the Alert Level was lowered to Yellow on 23 April.
Geologic Background. The Puyehue-Cordón Caulle volcanic complex (PCCVC) is a large NW-SE-trending late-Pleistocene to Holocene basaltic-to-rhyolitic transverse volcanic chain SE of Lago Ranco. The 1799-m-high Pleistocene Cordillera Nevada caldera lies at the NW end, separated from Puyehue stratovolcano at the SE end by the Cordón Caulle fissure complex. The Pleistocene Mencheca volcano with Holocene flank cones lies NE of Puyehue. The basaltic-to-rhyolitic Puyehue volcano is the most geochemically diverse of the PCCVC. The flat-topped, 2236-m-high volcano was constructed above a 5-km-wide caldera and is capped by a 2.4-km-wide Holocene summit caldera. Lava flows and domes of mostly rhyolitic composition are found on the E flank. Historical eruptions originally attributed to Puyehue, including major eruptions in 1921-22 and 1960, are now known to be from the Cordón Caulle rift zone. The Cordón Caulle geothermal area, occupying a 6 x 13 km wide volcano-tectonic depression, is the largest active geothermal area of the southern Andes volcanic zone.