Report on Llaima (Chile) — 9 April-15 April 2003
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 9 April-15 April 2003
Managing Editor: Gari Mayberry
Please cite this report as:
Global Volcanism Program, 2003. Report on Llaima (Chile). In: Mayberry, G (ed.), Weekly Volcanic Activity Report, 9 April-15 April 2003. Smithsonian Institution and US Geological Survey.
38.692°S, 71.729°W; summit elev. 3125 m
All times are local (unless otherwise noted)
Increased seismic and volcanic activity at Llaima during 9-11 April led officials to put the volcano at Alert Level Yellow. Seismic signals indicating weak eruptive activity were recorded and observations made during a flight revealed a thin layer of pyroclastic material atop a glacier on the NE flank. In addition to extensive fumarolic activity, observers saw new cracks in the glacier. Only weak fumaroles were seen during 12-13 April.
Geologic Background. Llaima, one of Chile's largest and most active volcanoes, contains two main historically active craters, one at the summit and the other, Pichillaima, to the SE. The massive, dominantly basaltic-to-andesitic, stratovolcano has a volume of 400 km3. A Holocene edifice built primarily of accumulated lava flows was constructed over an 8-km-wide caldera that formed about 13,200 years ago, following the eruption of the 24 km3 Curacautín Ignimbrite. More than 40 scoria cones dot the volcano's flanks. Following the end of an explosive stage about 7200 years ago, construction of the present edifice began, characterized by Strombolian, Hawaiian, and infrequent subplinian eruptions. Frequent moderate explosive eruptions with occasional lava flows have been recorded since the 17th century.