On 25 March, AVO reported that a small explosion from Redoubt produced an ash plume that rose to an altitude of 4.6 km (15,000 ft) a.s.l. and drifted N to NW. Later that day AVO lowered the Volcanic Alert Level to Watch and the Aviation Color Code to Orange because seismicity had decreased during the previous 36 hours. On 26 March, multiple explosive eruptions produced plumes to altitudes of 6.1-19.8 km (20,000-65,000 ft) a.s.l. or greater. AVO raised the Alert Level to Warning and the Aviation Color Code to Red, the highest levels. The largest eruption, at 0924, also produced a lahar in the Drift River valley that was detected by seismic instruments.
During 27-28 March, seven explosive eruptions produced ash plumes to altitudes of 7.6-15.2 km (25,000-50,000 ft) a.s.l. An ash plume on 29 March rose to an altitude of 6.1 km (20,000 ft) a.s.l. Seismic and infrasound data did not show clear evidence that the plume was generated by an explosion. On 30 March, continuously emitted ash plumes of varying intensities were observed in a web camera, on satellite and radar images, and by pilots, and rose to altitudes less than 6.1 km (20,000 ft) a.s.l. Occasionally, short-lived events produced ash plumes to an altitude of 8.2 km (27,000 ft) a.s.l. A thermal anomaly at the vent seen on satellite imagery was possibly due to the extrusion of a lava dome in the summit crater. On 31 March, emissions of steam, gas, and minor amounts of ash were seen on Redoubt Hut web camera. Resultant plumes rose to altitudes of 4.6-7.6 km (15,000-25,000 ft) a.s.l. Satellite images showed a broad layer of volcanic haze that extended E over the Kenai Peninsula, the Anchorage Bowl, and the Matanuska-Susitna Valley.
According to news articles, 11 people were evacuated on 23 March from the Drift River Terminal, an oil storage facility about 35 km ENE of Redoubt that shut down because of the eruption. During 24-28 March, flights in and out of Anchorage and other local areas continued to be canceled or diverted; as many as 185 Alaska Airlines flights had been canceled since the beginning of the eruption. Ashfall was occasionally reported in Anchorage and areas NW.
Sources: Alaska Volcano Observatory (AVO), The Associated Press – “Reports provided courtesy of the Smithsonian’s Global Volcanism Program and the US Geological Survey’s Volcano Hazards Program.”