Report on Llaima (Chile) — 2 July-8 July 2008
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 2 July-8 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, 2 July-8 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 although observations of Llaima were inhibited by cloud cover on 2 July, incandescence from the 1-km-long lava flow on the W flank was observed. An overflight revealed cooled blocks at the end of the lava flow and a second lava flow (on the SW flank) about 150 m S of the first. The lava flows issued from the base of a pyroclastic cone in the main crater. Observers to the W witnessed an explosion from the summit that ejected material 1 km high. The material landed on the SW flank and up to 3.5 km away on the SE flank. Vapor plumes from the main crater were seen on 3 July. An overflight on the same day revealed that the lava flow on the W flank had advanced and generated a small lahar.
On 4 July, SERNAGEOMIN characterized the eruptive style as weakly Strombolian. A small explosion from the pyroclastic cone in the main crater produced an ash plume that rose 250-400 m and drifted 50 km SE. During 4-5 July, observers reported sporadic explosions and incandescence at the summit. Fine ashfall was reported in areas nearby. On 6 July, seismicity decreased to low levels. An overflight on 7 July revealed that the lava emission rate had decreased for both flows. The lava flow on the W flank was about 1.6 km long and the flow on the SW flank was about 2 km long. Bluish gas was emitted from the main crater.
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.