The USGS reported that levels of seismicity at Anatahan were elevated during 27 February-4 March. During 27-29 February emissions of sulfur dioxide were detected by the satellite-based Ozone Monitoring Instrument (OMI). Based on observations of satellite imagery, the Washington VAAC reported that an ash plume drifted SSW on 28 February. The USGS reported that a second plume rose to an altitude of less than 3 km (10,000 ft) a.s.l. and drifted 240 km NW during 3-4 March.
Sources: Emergency Management Office of the Commonwealth of the Mariana Islands and the US Geological Survey Hawaiian Volcano Observatory, Washington Volcanic Ash Advisory Center (VAAC) – “Reports provided courtesy of the Smithsonian’s Global Volcanism Program and the US Geological Survey’s Volcano Hazards Program.”