Report on Puyehue-Cordon Caulle (Chile) — 30 November-6 December 2011
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 30 November-6 December 2011
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2011. Report on Puyehue-Cordon Caulle (Chile). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 30 November-6 December 2011. Smithsonian Institution and US Geological Survey.
40.59°S, 72.117°W; summit elev. 2236 m
All times are local (unless otherwise noted)
Based on seismicity during 30 November-6 December, OVDAS-SERNAGEOMIN reported that the eruption from the Cordón Caulle rift zone, part of the Puyehue-Cordón Caulle volcanic complex, continued at a low level. During 1-3 and 5 December plumes observed with the web camera rose 1.5-3 km above the crater. On 1 December satellite imagery showed an ash plume drifting 90 km SSE with sparse ashfall to the W and NW and dissipated 100 km to the SE. During the night the crater was incandescent. Satellite imagery showed an ash plume drifting E and SE and reaching the Atlantic Ocean on 2 December. Cloud cover prevented satellite data during 3-4 December. On 5 December satellite imagery showed a plume drifting 100 km NW. The Alert Level remained at Red.
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.