IG reported continuing activity at Tungurahua during 15-21 February.
Increased seismicity and constant harmonic tremor were detected on 16 February.
Based on information from the Guayaquil MWO and IG, the Washington VAAC reported that during 17-18 February emissions rose to an altitude of 6 km (19, 500 ft) a.s.l.
IG also noted that a steam plume with small amounts of ash drifted WSW on 19 February and W on 21 February.
Sources: Instituto Geofísico-Escuela Politécnica Nacional (IG), Washington Volcanic Ash Advisory Center (VAAC)