On 11 October Servicio Nacional de Geología y Minería (SERNAGEOMIN) reported that low levels of activity were detected at Villarrica during 16-30 September, characterized as a decrease in the frequency of explosions with ejection of high-temperature tephra outside the crater. A webcam located near the volcano recorded only gas-and-steam emissions rising to low heights, up to a maximum of 120 m above the crater rim, though weather clouds often prevented observations. Seismicity was low. Sulfur dioxide emissions averaged 525 ± 93 tonnes per day (t/d), with a maximum daily average of 618 t/d recorded on 26 September; these values were at baseline levels. The Volcanic Alert Level was lowered to Green (the lowest level on a four-level scale). SENAPRED decreased the restricted zone around the crater to 500 m, with a “Preventative Early Warning“ status issued for the communities of Villarrica, Pucón (16 km N), Curarrehue, and Panguipulli.

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), Sistema y Servicio Nacional de Prevención y Repuesta Ante Desastres (SENAPRED)