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Report on Chaiten (Chile) — 18 June-24 June 2008


Smithsonian Institution / US Geological Survey
Weekly Volcanic Activity Report, 18 June-24 June 2008
Managing Editor: Sally Sennert.

Please cite this report as:

Global Volcanism Program, 2008. Report on Chaiten (Chile) (Sennert, S, ed.). Weekly Volcanic Activity Report, 18 June-24 June 2008. Smithsonian Institution and US Geological Survey.

Weekly Report (18 June-24 June 2008)



42.8349°S, 72.6514°W; summit elev. 1122 m

All times are local (unless otherwise noted)

Based on observations during an overflight on 17 June, SERNAGEOMIN reported that ash plumes emitted from the S contact between Chaitén's old and new lava domes rose to an altitude of 2 km (6,600 ft) a.s.l. and drifted N and NW. An explosion temporarily propelled the ash plume to an altitude of 3 km (10,000 ft) a.s.l. and steam plumes rose from several other contact points along the S edge of the lava dome. Rockfalls from the active dome continued to descend the S flank of the old dome to the caldera floor. During 18-21 June, visual observations were inhibited due to inclement weather. During 18-20 June, possible ashfall was reported in Queilén (about 70 km W) and Quellón (about 80 km WSW). Ashfall was reported in Chaitén town (10 km SW) and other areas SE, W, and E. The Alert Level remained at Red.

Based on observations of satellite imagery, SIGMET reports, and pilot observations, the Buenos Aires VAAC reported that during 18-24 June ash plumes rose to altitudes of 2.4-4.6 km (8,000-15,000 ft) a.s.l. and drifted approximately NE, E, SE, SW, and W. Thermal anomalies were identified on satellite imagery on 19 and 22 June.

Geological Summary. Chaitén is a small caldera (~3 km in diameter) located 10 km NE of the town of Chaitén on the Gulf of Corcovado. Multiple explosive eruptions throughout the Holocene have been identified. 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 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 recorded eruption, beginning in 2008, produced major rhyolitic explosive activity and building a new dome and tephra cone on the older rhyolite dome.

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