Heavy ash falls were reported in several nearby communities and the eruption was accompanied by strong rumbling noises that were felt miles away.
Ash also blanketed several tracts of farmland to the west and south of Tungurahua.
Volcanic tremors began to rattle the region three days before the 16,479-foot mountain began to spew violently.
Geologists from the country’s Geophysical Institute said that the volcano was sending up a constant plume of ash and occasional pyroclastic flows that cascaded down part of its flanks.
Tungurahua has been active since awakening in 1999 from an 80-year period of dormancy.
The volcano became increasingly active during the final week of last November, sending pyroclastic boulders soaring into the Andean sky.
Several communities around the volcano’s flanks were forced to evacuate when the mountain awakened from an 80-year slumber in 1999. Some residents were unable to return to their homes a year later.
Tungurahua means "Throat of Fire" in the indigenous Quechua language.
Photo: Instituto Geofisico de Ecuador