Report on Villarrica (Chile) — April 1995
Bulletin of the Global Volcanism Network, vol. 20, no. 4 (April 1995)
Managing Editor: Richard Wunderman.
Villarrica (Chile) Tremor, mild explosions, and a new pyroclastic cone
Please cite this report as:
Global Volcanism Program, 1995. Report on Villarrica (Chile). In: Wunderman, R. (ed.), Bulletin of the Global Volcanism Network, 20:4. Smithsonian Institution. https://doi.org/10.5479/si.GVP.BGVN199504-357120.
39.42°S, 71.93°W; summit elev. 2847 m
All times are local (unless otherwise noted)
Gustavo Fuentealba contributed the following on 4 May. "Seismic activity has increased in the past few days compared to March. In mid-April explosions were visible to the level of the crater rim and these explosions coincided with seismicity registered on portable instruments 15 km from the crater. The seismic signals arrived at 90-second intervals.
"In agreement with mid-April explosions and seismic data, aerial observations and photos around that time (taken by members of the Corporacion Nacional Forestal) revealed the growth of a new pyroclastic cone. Starting on 28 April and 1 May, there were intervals of poor visibility, but a new increase in seismic activity included tremor at 30-second intervals. Seismic activity declined suddenly, starting about 1915 on 1 May, but it reappeared ~8 hours later with tremor at 60-second intervals. Although continued poor visibility thwarted direct observations, it was thought probable that the April pyroclastic cone had collapsed."
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: Gustavo Fuentealba1 and Paola Pena, Observatorio Volcanologico de los Andes del Sur. 1 Also at Universidad de la Frontera, Ciencias Fisicas, Avenida Francisco Salazar 01145, Casilla 54-D A 238, Temuco, Chile.