Based on OVDAS-SERNAGEOMIN data, representatives from ONEMI, SERNAGEOMIN, Sistema Nacional de Protección Civil, and others reduced the exclusion zone around Villarrica to 5 km on 5 March. OVDAS-SERNAGEOMIN reported that the Alert Level for Villarrica was lowered to Orange (the second highest level on a four-color scale) on 6 March, citing that seismicity had declined to below baseline levels and visual observations indicated no active lava lake. During an overflight on 9 March scientists observed subsidence of material in the crater which partially obscured the conduit. Weak degassing was also noted. On 10 March the Alert Level was lowered to Yellow; OVDAS-SERNAGEOMIN warned of avalanches of unconsolidated material and maintained an exclusion zone of 3 km.

Geological Summary. The glacier-covered Villarrica stratovolcano, in the northern Lakes District of central Chile, is ~15 km south of the city of Pucon. A 2-km-wide caldera that formed about 3,500 years ago is located at the base of the presently active, dominantly basaltic to basaltic-andesite cone at the NW margin of a 6-km-wide Pleistocene caldera. More than 30 scoria cones and fissure vents are present on 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. Eruptions documented since 1558 CE 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 Nacional de Geología y Minería (SERNAGEOMIN), Oficina Nacional de Emergencia-Ministerio del Interior (ONEMI)