Quilotoa is a truncated, dacitic cone that is the westernmost of Ecuador's Andean volcanoes. It is located at the margin of the Western Cordillera, 35 km WNW of the city of Latacunga and contains a 3-km-wide caldera with steep-sided walls that rise 400 m above the surface of 240-m-deep caldera lake. More than a half dozen lava domes form an circular array along the caldera's perimeter. This small volcano has produced eight major explosive eruptions during the past 200,000 years. Its most recent major eruption about 800 radiocarbon years ago produced voluminous pyroclastic flows, lahars that reached the Pacific Ocean, and one of the largest airfall-tephra deposits of the northern Andes. Formation of the caldera was followed by extrusion of a small lava dome. Reports of historical eruptions from the caldera lake are somewhat ambiguous. Fumaroles are present on the lake floor and hot springs occur on the eastern flank.