Report on Llaima (Chile) — 20 August-26 August 2008
Smithsonian / US Geological Survey Weekly Volcanic Activity Report,
20 August-26 August 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, 20 August-26 August 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 steam plumes from the pyroclastic cones in Llaima's main crater were visible during periods of clear weather on 16 August. Steam plumes rose from the W flank where lava flows were active in February and July. On 17 August, sporadic gas-and-ash emissions were observed. Cloud cover prevented observations during 18-20 August. On 21 August, three explosions produced ash plumes that rose to an altitude of 3.6 km (11,800 ft) a.s.l. and drifted E. Gas and steam was emitted in between explosions; resultant plumes rose to an altitude of 3.4 km (11,200 ft) a.s.l. and drifted 9 km E. During an overflight, scientists observed steam-and-gas plumes being emitted from a small crater in the N sector of the main crater. A larger crater, about 100 m in diameter, in the central sector emitted ash. The ash plumes rose to an altitude of 3.4 km (11,200 ft) a.s.l. and drifted E. A thin layer of ash blanketed the E flank. Ash-and-gas plumes from the main crater drifted W on 22 August. On 23 August, observers reported that incandescent material was ejected less than 1 km above the crater. The next day, an ash plume drifted about 1.5 km SSE. Ash blanketed some areas of the flanks. The Volcano Alert Level remained at Yellow.
Geological Summary. 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.