During an overflight of Villarrica on 19 November, SERNAGEOMIN scientists observed a cone on the crater floor with an incandescent vent at its center, containing a lava lake. Deposits of ejected material were seen on the flanks. That same day a 75-minute-long series of volcano-tectonic earthquakes began at 1940. There was a total of 21 events located 7.8 km ESE of the crater. The largest event, a M 1.6, occurred at 2007 at a depth of 2.5 km based on data collection and analysis of Red Nacional de Vigilancia Volcánica (RNVV) and Observatorio Volcanológico de los Andes del Sur (OVDAS), respectively. The Alert Level remained at Yellow (the second lowest level on a four-color scale) and the public was warned that material could be ejected within 500 m of the crater. ONEMI remained the Alert Level Yellow (the middle level on a three-color scale) for the municipalities of Villarrica, Pucón (16 km N), Curarrehue, and the commune of Panguipulli.

Geological Summary. Glacier-clad Villarrica, one of Chile's most active volcanoes, rises above the lake and town of the same name. It is the westernmost of three large stratovolcanoes that trend perpendicular to the Andean chain. A 6-km-wide caldera formed during the late Pleistocene. A 2-km-wide caldera that formed about 3500 years ago is located at the base of the presently active, dominantly basaltic to basaltic-andesitic cone at the NW margin of the Pleistocene caldera. More than 30 scoria cones and fissure vents dot the flanks. Plinian eruptions and pyroclastic flows that have extended up to 20 km from the volcano were produced during the Holocene. Lava flows up to 18 km long have issued from summit and flank vents. Historical eruptions, documented since 1558, have consisted largely of mild-to-moderate explosive activity with occasional lava effusion. Glaciers cover 40 km2 of the volcano, and lahars have damaged towns on its flanks.

Sources: Servicio Geológico Minero Argentino (SEGEMAR), Servicio Nacional de Geología y Minería (SERNAGEOMIN), Oficina Nacional de Emergencia-Ministerio del Interior (ONEMI)