On 12 May, OVDAS-SERNAGEOMIN reported that a slight increase in activity from Villarrica during April led to a change in the Alert Level from Green Level 1 to Green Level 2. April's activity was characterized by increased seismicity, a rise in the lava lake level, more vigorous fumarolic activity, and more frequent incandescence at night. According to the Projecto Observación Visual Volcán Villarrica (POVI), the spattering lava lake was about 100 m below the crater rim on 10 May.

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), Proyecto Observación Villarrica Internet (POVI)