Report on Villarrica (Chile) — May 1992
Bulletin of the Global Volcanism Network, vol. 17, no. 5 (May 1992)
Managing Editor: Lindsay McClelland.
Villarrica (Chile) Volcanic earthquakes and tremor
Please cite this report as:
Global Volcanism Program, 1992. Report on Villarrica (Chile). In: McClelland, L (ed.), Bulletin of the Global Volcanism Network, 17:5. Smithsonian Institution. https://doi.org/10.5479/si.GVP.BGVN199205-357120.
39.42°S, 71.93°W; summit elev. 2847 m
All times are local (unless otherwise noted)
Seismicity was recorded at the volcano during March-May by a telemetered seismic station (VNV) 4.5 km from the summit, at 1,400 m elev. The average tremor frequency decreased slightly from 1.9 Hz (in March-April) to 1.8 Hz (in May). Tremor frequency also decreased with distance from the summit. Average frequencies of 1.9, 0.8, and 0.6 Hz were recorded 4.5 km (station VNV), 18.7 km (station PP) and 21 km (station PL) from the volcano, respectively, in April. Since 28 May, activity has increased, and both tremor and volcanic earthquakes have been recorded.
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.
Information Contacts: G. Fuentealba and P. Peña, Univ de La Frontera; M. Petit-Breuilh, Fundación Andes, Temuco.