April 2011 Eruption of Tungurahua

On 22 April, 2011, Instituto Geofísico (Ecuador) reported that in recent months the seismic network at Tungurahua detected volcano-tectonic earthquakes, indicating increased pressure in the volcano. Deformation of the NW quadrant that began in early February was slow but continuous, and then accelerated during the previous nine days. On 21 April gas-and-ash plumes caused fine ashfall in Choglontús and Cahuají (8 km SW), Pillate (8 km W), Cotaló (8 km NW), Juive (7 km NNW), and Baños (8 km N). Strombolian activity was seen at night, producing small lava fountains and incandescent blocks that rolled 1 km down the flanks. Roaring was heard and a few explosions occurred during 21-22 April. Instituto Geofísico (Ecuador) recommended that residents do not go within 3 km of Tungurahua's crater. On 26 April six explosions were detected and constantly-generated ash plumes rose to an altitude of 12 km (39,400 ft) a.s.l. Plumes drifted W and NW, causing steady ashfall in areas downwind. Structures vibrated in surrounding areas, including in Baños. (reference #2432)

A plume more than 7km (4.3 miles) high could be seen emerging from the volcano in central Ecuador. The authorities evacuated residents living near the volcano's rim and ordered local schools to close. The Tungurahua has erupted periodically over the past 12 years, but this is its first significant activity this year. Monitors said they detected six eruptions, ranging from moderate to large. "According to our observations, damages to crops, pastures and small effects to the health of people are already evident," the Ecuadorean geophysics institute said. (reference #10332)