RVO reported that during 9-13 April ash and steam-and-ash plumes rose to altitudes of 1.7-2.2 km (5,600-7,200 ft) a.s.l. and drifted W and NW. Ashfall was reported in areas downwind, including Rabaul Town (3-5 km NW). Incandescence at night at the summit and intermittent roaring noises were reported. A large explosion on 10 April showered the flanks with lava fragments and produced a shockwave that rattled windows in Rabaul Town.
Source: Steve Saunders and Harman Patia, Rabaul Volcano Observatory (RVO) – “Reports provided courtesy of the Smithsonian’s Global Volcanism Program and the US Geological Survey’s Volcano Hazards Program.”