The country's Geophysical Institute says incandescent rock shot from the crater of the 16,479-foot high mountain fell about half a mile down its flanks. Explosions early Wednesday rattled windows 9 miles away, while rain-borne ash has been falling to the southwest of the crater.
Regional emergency director Lourdes Mayorga says that about 100 families are staying in shelters away from the danger zone, though they return during the day to work their fields. She says there will be forced evacuations if the volcanic activity intensifies.
Tungurahua has been active for the past 13 years. An outburst in 2006 left four dead and two missing.