SERNAGEOMIN reported that on 19 January spine collapses from Chaitén's Domo Nuevo 2 produced block-and-ash flows that traveled down the SE and E flanks. An overflight on 21 January revealed landslide scars on the E flank of Domo Nuevo 2. Reddish-brown ash plumes rose from the active dome. A thermal camera showed that the greater temperature anomalies originated from the top of Domo Nuevo 2; anomalies were also present on Domo Nuevo 1 and on many block-and-ash flow deposits. The Alert Level remained Red.

Based on analysis of satellite imagery and web camera views, the Buenos Aires VAAC reported that during 21-22 and 25-27 January ash plumes rose to altitudes 1.8-2.4 km (6,000-8,000 ft) a.s.l. and drifted E and NE.

Geological Summary. 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)