Atacazo volcanAtacazo volcano is part of the Atacazo–Ninahuilca Volcanic Complex in the Western Cordillera of Ecuador and located 10 km southwest of the capital of Ecuarod, Quito.
The andesitic Atacazo stratovolcano is a successor of the older La Carcacha stratovolcano. It was built above a 6 km wide and 900 m deep caldera. The caldera is breached to the SW and contains 3 Holocene dacitic domes. The youngest lava dome, Ninahuilca, erupted about 2300 years ago. 2 andesitic lava domes are also found on the SE flank.
Several large Plinian eruptions have occurred at the volcano during the past 10,000 years and accompanied the growth of the lava domes. The formation of the most recent dome, Ninahuilca Chico, was accompanied by explosive eruptos that produced pyroclastic flows that flowed up to 35 km distance through valleys towards the west.
Introduction:Several towns built on the deposits of past eruptions and are considered to be at high risk areas in case of a new major explosive eruption. These include the towns and villages of Tambillo, Uyumbicho, Aloag, Tandapi, Canchacoto.
A stretch of the main Panamerican highway, crossing the highlands from north to south, as well as the road from Aloag to Santo Domingo, linking the Northern highlands to the Coastal region, are also built in the high risk area.
Typical quiescence intervals of Atacazo volcano range between 1000–4000 years. Statistically, the risk of a new eruption is increasing, because the last major eruption is 2300 years back. A future eruption could affect about 70,000 people.
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