Report on Chaiten (Chile) — 15 July-21 July 2009

Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 15 July-21 July 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, 15 July-21 July 2009. Smithsonian Institution and US Geological Survey.

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Chaiten

Chile

42.833°S, 72.646°W; summit elev. 1122 m

All times are local (unless otherwise noted)


Based on web camera views from the S, SERNAGEOMIN reported that during 8-15 July gas-and-ash plumes rose 1.2 km from Chaitén's growing Domo Nuevo 1 and Domo Nuevo 2 lava-dome complex. Collapses originating from unstable slopes generated block-and-ash flows, particularly in the W area of the complex. The Alert Level remained at Red. Based on web camera views, analyses of satellite imagery, and a SIGMET notice, the Buenos Aires VAAC reported that during 16, 19, and 21 July ash plumes rose to altitudes of 1.8-2.4 km (6,000-8,000 ft) a.s.l. and drifted NNE, SE, and SSW. Thermal anomalies were detected in satellite imagery on 16 and 19 July.

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.

Sources: Buenos Aires Volcanic Ash Advisory Center (VAAC), Servicio Nacional de Geología y Minería (SERNAGEOMIN)