Relatively high volcanic activity continued at Tungurahua during 10-17 June. Several explosions took place, with the highest rising ash plume reaching ~5 km above Tungurahua. Some explosions were heard in towns near the volcano and on 10 June vibrations from an explosion were felt in the town of Baños. Significant amounts of ash fell in several villages, including Quero and Pelileo. Strombolian activity during the evening of 15 June consisted of incandescent blocks that were hurled to ~150 m above the crater and rolled ~1 km down Tungurahua's N flank. Ash fell in the sector of Cusúa. During the report week, ash clouds were visible on satellite imagery.

Geological Summary. Tungurahua, a steep-sided andesitic-dacitic stratovolcano that towers more than 3 km above its northern base, is one of Ecuador's most active volcanoes. Three major edifices have been sequentially constructed since the mid-Pleistocene over a basement of metamorphic rocks. Tungurahua II was built within the past 14,000 years following the collapse of the initial edifice. Tungurahua II collapsed about 3,000 years ago and produced a large debris-avalanche deposit to the west. The modern glacier-capped stratovolcano (Tungurahua III) was constructed within the landslide scarp. Historical eruptions have all originated from the summit crater, accompanied by strong explosions and sometimes by pyroclastic flows and lava flows that reached populated areas at the volcano's base. Prior to a long-term eruption beginning in 1999 that caused the temporary evacuation of the city of Baños at the foot of the volcano, the last major eruption had occurred from 1916 to 1918, although minor activity continued until 1925.

Sources: Washington Volcanic Ash Advisory Center (VAAC), Instituto Geofísico-Escuela Politécnica Nacional (IG)