On 24 February, SERNAGEOMIN reported that an overflight of Chaitén’s Domo Nuevo 1 and Domo Nuevo 2 lava-dome complex revealed that a large amount of material from the 19 February partial dome collapse had accumulated in the basal ring depression surrounding the dome complex and throughout the Chaitén (Blanco) River valley. Most of the collapsed material originated from Domo Nuevo 1. Steam plumes with little ash content rose from the N part of Domo Nuevo 2 and steam and brown ash plumes were emitted from a central spine complex. Steam plumes and sporadic explosions were noted from the S part of Domo Nuevo 1; producing four plumes that mixed and rose 1.5 km above the complex. Small collapses, originating from unstable slopes of the SE part of Domo Nuevo 1, generated block-and-ash flows.
On 26 February, observers in Chaitén town (10 km SW) reported that plumes rose 2 km above the complex. During 26-27 February, small collapses caused the plume to occasionally enlarge and turn brown. On 27 February, an overflight revealed that the S part of Domo Nuevo 1 continued to grow. Numerous fan-shaped deposits from collapses were seen on the S slope. Based on web camera views, the Buenos Aires VAAC reported that during 27 February, and 2-3 March plumes rose to altitudes of 2.1-2.4 km (7,000-8,000 ft) a.s.l. Plumes drifted E on 27 February and SE on 3 March.
Sources: Servicio Nacional de Geología y Minería (SERNAGEOMIN), Buenos Aires Volcanic Ash Advisory Center (VAAC) - “Reports provided courtesy of the Smithsonian’s Global Volcanism Program and the US Geological Survey’s Volcano Hazards Program.”