SERNAGEOMIN reported that during 10-16 March Chaitén's Domo Nuevo 1 and Domo Nuevo 2 lava-dome complex continued to grow. Collapses, originating from unstable slopes of the SE part of Domo Nuevo 1 and from a central spine complex, generated block-and-ash flows. Material from the collapses was channeled towards the Chaitén (Blanco) River valley. Ash-and-gas plumes drifted mainly SE. Based on web camera views and SIGMET notices, the Buenos Aires VAAC reported that during 20-21 and 23 March ash plumes rose to altitudes of 2.1-2.4 km (7,000-8,000 ft) a.s.l. and drifted E and NE.

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)