Report on Chaiten (Chile) — 2 September-8 September 2009
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 2 September-8 September 2009
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2009. Report on Chaiten (Chile). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 2 September-8 September 2009. Smithsonian Institution and US Geological Survey.
42.833°S, 72.646°W; summit elev. 1122 m
All times are local (unless otherwise noted)
SERNAGEOMIN reported that during 20-31 August Chaitén's Domo Nuevo 1 and Domo Nuevo 2 lava-dome complex continued to grow, particularly in the W area of the complex. Collapses originating from unstable slopes generated block-and-ash flows, and gas-and-ash plumes occasionally rose 1.5 km above the lava domes. The Alert Level remained at Red. Based on web camera views and analyses of satellite imagery, the Buenos Aires VAAC reported that on 6 September an ash plume rose to an altitude of 2.4 km (8,000 ft) a.s.l. and drifted E. The next day, a plume rose to an altitude of 2.1 km (7,000 ft) a.s.l. and drifted NE.
Geologic Background. Chaitén is a small, glacier-free caldera with a compound Holocene lava dome located 10 km NE of the town of Chaitén on the Gulf of Corcovado. Early work had identified only a single explosive eruption during the early Holocene prior to the major 2008 eruption, but later work has identified multiple explosive eruptions throughout the Holocene. A rhyolitic obsidian lava dome occupies much of the caldera floor. Obsidian cobbles from this dome found in the Blanco River are the source of prehistorical artifacts from archaeological sites along the Pacific coast as far as 400 km from the volcano to the N and S. The caldera is breached on the SW side by a river that drains to the bay of Chaitén. The first historical eruption, beginning in 2008, produced major rhyolitic explosive activity and growth of a lava dome that filled much of the caldera.