Based on web camera views, SERNAGEOMIN reported that during 20-27 May gas-and-ash plumes rose 1.5 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 that were sometimes seen from Chaitén town, 10 km SW. Seismicity remained elevated; the hypocenters of the large hybrid earthquakes were located under the W part of the complex at depths of 5-9 km. The Alert Level remained at Red. Based on web camera views, the Buenos Aires VAAC reported that during 28-29 May and 1-2 June ash plumes rose to altitudes of 1.8-2.4 km (6,000-8,000 ft) a.s.l. Thermal anomalies were also seen in satellite imagery on all three days.

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