Based on observations of satellite imagery and SIGMET reports, the Buenos Aires VAAC reported that during 14-19 May ash plumes from Chaitén rose to altitudes of 5.5-9.1 km (18,000-30,000 ft) a.s.l. and drifted N, NE, and E. Cloudy conditions often inhibited observations. A thermal anomaly was present in the crater on 19 May.
Based on estimates made during an overflight of the area, ONEMI reported on 14 May that about 90 percent of the town of Chaitén was flooded. SERNAGEOMIN reported that on 15 May ashfall accumulated up to 1 mm thick on a ship and an island to the W, and several areas inland were white due to ash cover. Lahars continued to cause the Chaitén and Blanco-Rayas rivers to overflow, affecting new areas in Chaitén town. The Alert Level remained at Red.
According to news articles, the military evacuated small groups of mostly journalists and troops remaining in areas near Chaitén on 19 May. A court ordered police to use force if necessary to move the few remaining people that refused to evacuate to areas outside of the 50 km high-risk zone.
Sources: Servicio Nacional de Geología y Minería (SERNAGEOMIN), Oficina Nacional de Emergencia – Ministerio del Interior (ONEMI), Buenos Aires Volcanic Ash Advisory Center (VAAC), Reuters – “Report provided courtesy of the Smithsonian’s Global Volcanism Program and the US Geological Survey’s Volcano Hazards Program.”