Report on Villarrica (Chile) — 25 March-31 March 2015
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 25 March-31 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 March-31 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 during 24-25 March gas-and-ash emissions at Villarrica decreased but the magnitude of the continuous seismic tremor slightly increased. Crater incandescence overnight was observed. By the evening of 25 March Strombolian activity was confined to the crater and a gas plume rose 700 m above the crater rim. Seismicity fluctuated but increase overall. The lava lake had returned and was about 1,000 degrees Celsius. During 26-27 March Strombolian activity ejected tephra out of the crater to distances of about 500 m, and a gas plume rose more than 800 m. During an overflight on 27 March scientists noted that material which measured 1,110 degree Celsius originated from two vents. During 28-31 March a gas-and-ash plume rose from the crater and Strombolian explosions ejected tephra from the crater; several explosions starting at 2200 on 30 March, and continuing the next morning, ejected tephra 300 m above the crater and as far as 500 m from the crater onto the flanks. The Alert Level remained at Orange (the second highest level on a four-color scale) and the public was warned to stay outside of a 5-km radius around the crater and away from drainages.
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.