Report on Puyehue-Cordon Caulle (Chile) — 1 January-7 January 1920
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 1 January-7 January 1920
Managing Editor: Gari Mayberry
Please cite this report as:
Global Volcanism Program, 1920. Report on Puyehue-Cordon Caulle (Chile). In: Mayberry, G (ed.), Weekly Volcanic Activity Report, 1 January-7 January 1920. Smithsonian Institution and US Geological Survey.
40.59°S, 72.117°W; summit elev. 2236 m
All times are local (unless otherwise noted)
Significantly increased seismicity over a period of a few days led to the evacuation of 700 residents on 4 June. Later that day, an explosion produced a 5-km-wide ash-and-gas plume that rose to altitudes of 10.7-13.7 km (35,000-45,000 ft) a.s.l. and drifted 870 km ESE. The next day an ash plume continued to rise to altitudes of 10.7-12.2 km (35,000-40,000 ft) a.s.l. and had drifted as far as 1,778 km ESE, over the coast of Argentina, and out into the Atlantic Ocean, disrupting flights. During 4-5 June ashfall several centimeters thick was reported 100 km SE in Argentina. At least five pyroclastic flows, possibly as long as 10 km, were generated from partial collapses of the eruptive column and traveled N in the Nilahue River drainage. Pumice and vitreous tephra had accumulated in many area lakes and rivers, and ash had turned many rivers darker. Poor visibility and flight disruptions continued on 10 June. On 13 June the eruptive vent diameter was 300-400 m. Gas-and-steam plumes rose from two or three locations along the same fissure as the eruptive vent. Ashfall and column collapses were visible. At night incandescence from the base of the plume reached 1.5-2 km high. By 17 June ash plumes had circumnavigated the globe. Flights in South Africa were disrupted during 18-19 June. A 50-m-wide lava flow from the emissions center had traveled 200 m NW and 100 m NE, filling up a depression by 20 June.
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.