Report on Llaima (Chile) — 9 January-15 January 2008
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 9 January-15 January 2008
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2008. Report on Llaima (Chile). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 9 January-15 January 2008. Smithsonian Institution and US Geological Survey.
38.692°S, 71.729°W; summit elev. 3125 m
All times are local (unless otherwise noted)
SERNAGEOMIN reported that seismicity from Llaima decreased in energy, but the number of events increased during 10-14 January. Based on seismic interpretation, weak explosions produced plumes of gas and ash. On 11 January, lava flows on the W flank that were observed during an overflight were cooled and snow-covered near the crater but snow-free, and therefore still hot, about 500 m further down on the flank. Blocks of incandescent material rolled about 1.5 km and caused steam emissions at several points where they contacted the glacier. Ash plumes drifted NE. Abundant cracks in glaciers to the SW of the crater were noted. Based on observations of satellite imagery and pilot reports, the Buenos Aires VAAC reported that ash plumes rose to an altitude of 5.5-6.7 km (18,000-22,000 ft) a.s.l. and drifted NE and SW on 11 and 13 January, respectively.
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.