The IG reported that although visual observations were occasionally limited due to cloud cover during 21-27 May, ash and ash-and-steam plumes, often generated by explosions from Tungurahua, were spotted and rose to altitudes of 5.8-9 km (19,000-29,500 ft) a.s.l. Ash plumes drifted SW, W, and NW and ashfall was reported daily in areas within 8 km downwind. Roaring noises, “cannon shot” noises, and sounds resembling blocks rolling down the flanks were reported. On 22, 25, 26, and 27 May, windows vibrated in nearby areas, including at the Tungurahua Observatory (OVT) in Guadalupe, 11 km N. On 23 May, incandescence at the summit was seen at night. On 27 May, lahars descended a drainage in the Pampas sector to the S.
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.”