Based on seismicity during 16-20 November, 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. Cloud cover prevented web camera views on 16 November, but satellite imagery showed an ash plume drifting 100 km SW and sparse ashfall to the E. During 18-20 November plumes observed with the web camera rose 2.5-3 km above the crater. Satellite imagery showed ash clouds drifting E and SE on 18 November and an ash plume drifting 250 km SE on 19 November. During the night on 20 November the crater was incandescent. Cloud cover prevented observations on 21 November. The Alert Level remained at Red.

According to a news article, flights in Uruguay and Argentina were disrupted or cancelled on 22 November due to the presence of ash.

Geological Summary. 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.

Sources: Servicio Nacional de Geología y Minería (SERNAGEOMIN), Agence France-Presse (AFP)