Report on Chaiten (Chile) — 14 January-20 January 2009

Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 14 January-20 January 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, 14 January-20 January 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)


SERNAGEOMIN reported that seismicity from Chaitén increased during 9-12 January. The unstable slopes of Domo Nuevo 2 and spine collapses continued to produce block-and-ash flows. Based on SIGMET notices, analysis of satellite imagery, and web camera views, the Buenos Aires VAAC reported that on 15, 17, 19, and 20 January ash plumes rose to altitudes 1.5-2.1 km (5,000-7,000 ft) a.s.l. and drifted NE, E, and SE. A small thermal anomaly was detected in satellite imagery on 19 January.

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)