Report on Chaiten (Chile) — 28 May-3 June 2008

Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 28 May-3 June 2008
Managing Editor: Sally Kuhn Sennert

Please cite this report as:

Global Volcanism Program, 2008. Report on Chaiten (Chile). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 28 May-3 June 2008. 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 observations of satellite imagery, SIGMET reports, and pilot observations, the Buenos Aires VAAC reported that during 28 May-3 June continuous ash plumes from Chaitén rose to altitudes of 3-6.4 km (10,000-21,000 ft) a.s.l. and drifted N, NE, E, and SE. Cloudy conditions occasionally inhibited observations.

SERNAGEOMIN reported ash plumes that rose to altitudes of 3.5-4 km (11,200-13,100 ft) a.s.l. and drifted N, NNE, and W during 28 May-2 June. Beaches to the W and N (about 12 km away) continued to accumulate pumice up to 40 cm in diameter carried to the ocean by the Yelcho, Negro, and Chaitén rivers. On 28 May, the ash affected towns and caused airport closings hundreds of kilometers N. A dense layer of mist with suspended ash, about 1.5 km thick and continuous around the volcano on 31 May, resulted in poor visibility. An ash plume at an altitude of 4 km (13,100 ft) a.s.l. was observed above the layer on 30 May. 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.

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