The IG reported that during 23 and 25-29 December ash plumes from Tungurahua rose to altitudes of 6-9 km (19,700-29,500 ft) a.s.l. and drifted mostly S, SW, W, and NW. On 23 December incandescent material rolled down Tungurahua’s flanks and a possible pyroclastic flow traveled 700 m down the NW flank. Ashfall was reported and explosions vibrated windows and the ground in areas to the SW. During 24-29 December roaring and “cannon shot” noises were reported almost daily; windows and the ground vibrated on 24, 28, and 30 December. A lahar traveled SW down the Mapayacu ravine on 27 December. Incandescence at the summit and ashfall in areas downwind were noted on 25, 26, 28, and 29 December. Explosions ejected blocks that rolled 500 m down the flanks on 25 December, 1500 m on 29 December, and 800 m on 30 December. On 30 December heavy black ash fell in areas to the SW.
Source: Instituto Geofísico-Escuela Politécnica Nacional (IG) – “Reports provided courtesy of the Smithsonian’s Global Volcanism Program and the US Geological Survey’s Volcano Hazards Program.”