Report on Llaima (Chile) — 23 July-29 July 2008
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 23 July-29 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, 23 July-29 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 cloud cover prevented observations of Llaima during 22-23 July. On 24 July a bluish gas was emitted from a pyroclastic cone in the main crater and steam plumes rose from the W margin of the crater. Later that day, gas-and-ash plumes rose 100 m above the crater and dissipated to the SSE. During an overflight prompted by increased seismicity on 26 July, scientists observed weak explosions and airborne spatter from a double crater at the N base of the pyroclastic cone. Area residents reported hearing "detonations" coming from the direction of the volcano and they observed small ash plumes. Strombolian activity intensified and ejected material 500-800 m above the crater. Rhythmic explosions ejected spatter 1 km above the summit and up to 2 km towards the E. A plume rose to an altitude of 10 km (32,800 ft) a.s.l. Lava flows emitted at a high rate descended the W and S flanks and ice evaporated, producing steam plumes. SERNAGEOMIN raised the Alert Level to Red.
SERNAGEOMIN reported that the eruption during 26-27 July lasted for 11.5 hours. During 28 and 29 July, the volcano was in a state of calm.
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.