Report on Llaima (Chile) — 25 June-1 July 2008
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 25 June-1 July 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, 25 June-1 July 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 sporadic gas-and-ash plumes from Llaima were seen when the weather was clear during 1-20 June. More frequent and continuous gas emissions rose from the nested cone in the main crater. Seismicity increased during 13-16 June. Towards the end of the observation period, steam plumes rose from the W flank. ONEMI reported that during an overflight on 26 June, bluish gas and ash rose from the top of an active pyroclastic cone in the main crater and the NE flank was not covered with snow, in contrast to other portions of the volcano. On 1 July, a lava flow on the W flank was seen from nearby communities prompting authorities to evacuate about 20-30 people and warn others of possible further evacuations. The lava flow descended the W flank to 800-1000 m from the crater, raising concern for lahars in the Calbuca river. The Alert Level was raised to Yellow (the middle level on a 3-level color system).
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.