Report on Chaiten (Chile) — 25 March-31 March 2009
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 25 March-31 March 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, 25 March-31 March 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 17-23 March Chaitén's lava-dome complex continued to grow from an area that includes the central spines and part of Domo Nuevo 1. This was also the main area where collapses from unstable slopes caused block-and-ash flows. Continuously emitted steam plumes with varying amounts of tephra and gas-and-ash plumes generated by block-and-ash flows drifted N and ESE. The block-and-ash flow volume was smaller compared to the previous week. The Alert Level remained at Red.
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.