During 6-12 August IG reported that moderate to high eruptive activity continued at Tungurahua. On 6, 8-9, and 11 August clouds obscured most views of the volcano, but frequent explosion sounds were heard that, on 9 August, shook structures in areas near and around the volcano. On 7 and 10 August Strombolian activity expelled incandescent blocks 500 m below the summit; on 7 August the blocks traveled primarily down the W flank. On 7-9 and 11 August ash and steam-and-ash plumes rose 1-1.5 km (3,300-4,900 ft) a.s.l. and drifted W and WNW. On 7 August ash was reported in the town of Quero and 8 August in El Manzano, Pillate, Cahuají and Tisaleo. On 8 August morning rains produced lahars that flowed down the ravines Achupashal, Pingullo and Chontapamba, that interrupted traffic on the Baños-Penipe road. On 9 August night rains caused lahars that flowed down streams Juive and La Pampa. Washington VAAC reported ongoing ash emissions on 6-12 August that, on 7 August, rose 6-6.4 km (20000-21000 ft) a.s.l.

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