SERNAGEOMIN reported that the eruption in Villarrica’s summit crater continued during 26 September-3 October. Strombolian activity was observed almost nightly and largely confined to the crater, though sometimes material was ejected beyond the crater onto the upper flanks; weather conditions sometimes prevented visual observations of the summit. Satellite images from 26 September showed a spatter cone on the crater floor with one vent measuring 10 x 14 m, and a smaller vent about 35 m NE of the cone. During 26-27 September there were deposits of bombs around the upper flanks within 150 of the crater rim and several impact craters on the snow from explosive activity. Discrete emissions with low ash content were visible. Steam-and-gas emissions were visible during 27-28 September and tephra was ejected onto the upper NW flank. Steam-and-gas emissions sometimes contained ash during 28-29 September; a period of continuous ash emissions recorded during 1020-1250 on 29 September rose 60 m above the crater rim and drifted NW.

During an overflight on 29 September scientists observed lava in the vent and deposits of blocks in the crater. A satellite image showed ash deposits on the WNW flank as far as 3 km from the crater. Material was ejected from the crater several times during 29-30 September, with the emissions varying in duration and tephra content; notably, at 0740 on 30 September a pulsating ash plume rose 1.1 km above the crater rim and drifted NNW. Deposits on the S flank extended as far as 4.5 km from the crater rim as seen in 30 September satellite images. Steam-and-gas emissions with no or low ash content rose to lower heights on 1 October. Incandescence lit up the bases of two gas plumes, rising from the two vents, on 2 October, and dense white gas plumes rose as high as 300 m on 3 October. The Volcanic Alert Level remained at Orange (the third level on a four-level scale) and the public was warned to stay 8 km away from the crater. SENAPRED maintained the Alert Level at Yellow (the middle level on a three-color scale) 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)