Report on Chaiten (Chile) — 20 May-26 May 2009

Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 20 May-26 May 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, 20 May-26 May 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 time-lapse photographs of Chaitén taken during 12-19 May showed the continued eruption of the Domo Nuevo 1 and Domo Nuevo 2 lava-dome complex. Gas-and-ash plumes that varied in color from white to gray rose 1.5 km above the complex. Collapses originating from unstable slopes of the lava domes generated block-and-ash flows. Growth was concentrated in the SW area of the lava-dome complex. The Alert Level remained at Red. Based on web camera views, analysis of satellite imagery, and a SIGMET notice, the Buenos Aires VAAC reported that on 21 and 26 May ash plumes rose to altitudes of 2.4-3.7 km (8,000-12,000 ft) a.s.l. Plumes drifted SSE on 21 May and 45-50 km NE on 26 May.

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)