On 11 November, SERNAGEOMIN reported that, although seismic events at Chaitén's lava-dome complex continued to increase in the previous weeks, the magnitudes of the earthquakes remained relatively low. Gas-and-steam plumes rose 300-400 m above the caldera rim. Based on analyses of satellite imagery and web camera footage, the Buenos Aires VAAC reported that on 13 November a gas-and-ash plume rose to an altitude of 1.5 km (5,000 ft) a.s.l. and drifted 40 km SE. On 15 November ash plumes observed through the web camera rose to altitudes of 1.8-2.1 km (6,000-7,000 ft) a.s.l. and drifted E. The Alert Level remained Yellow Level 3 on a three-color scale.

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)