Report on Villarrica (Chile) — 25 February-3 March 2015
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 25 February-3 March 2015
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2015. Report on Villarrica (Chile). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 25 February-3 March 2015. Smithsonian Institution and US Geological Survey.
39.42°S, 71.93°W; summit elev. 2847 m
All times are local (unless otherwise noted)
OVDAS-SERNAGEOMIN reported that on 28 February a significant increase in seismicity at Villarrica was detected along with Strombolian explosions and tephra ejected 1 km away. Seismicity continued to increase and on 2 March indicated that the lava lake level had risen. Strombolian explosions continued and ejected tephra as far as 600 m onto the flanks. Seismicity again increased significantly at 0230 on 3 March. The Alert Level was raised to Red (the highest level on a four-color scale). Strombolian activity intensified and became continuous, ejecting a large volume of material onto the flanks and producing a 1.5-km-tall lava fountain. Lava flows descended the flanks. The eruptive plume rose 6-8 km above the crater and drifted 400 km ENE. According to ONEMI about 3,600 people were evacuated from a 10-km-radius of the volcano. At 1500 ONEMI reported that seismicity was decreasing, and by 1800 was low. Only weak pulses of ash rose from the crater, and most evacuees had returned home.
Geologic Background. 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.