RVO reported that during 20-26 December gray ash plumes from Rabaul caldera’s Tavurvur cone rose to altitudes of 1.7-2.2 km (5,600-7,200 ft) a.s.l. and drifted SE and W. Ashfall was reported in areas downwind, including Kokopo Town (SE). Rumbling and roaring noises were reported on some days. Explosions or forceful emissions sometimes ejected incandescent lava fragments that fell back into the crater and occasionally onto the slopes.
Based on analysis of satellite imagery and pilot observations, the Darwin VAAC reported that on 30 December an ash plume rose to altitudes of 1.8-2.4 km (6,000-8,000 ft) a.s.l. and drifted N and NW.
Sources: Ima Itikarai, Rabaul Volcano Observatory (RVO), Darwin Volcanic Ash Advisory Centre (VAAC) – “Reports provided courtesy of the Smithsonian’s Global Volcanism Program and the US Geological Survey’s Volcano Hazards Program.”