Mojanda, one of the largest volcanoes of Ecuador's northern Interandean Depression, rises SW of the historic town of Otavalo. Volcán Mojanda has a complex geologic history involving two adjacent simultaneously active volcanoes. An earlier edifice contains remnants of a larger earlier caldera and a smaller summit caldera occupied by two lakes. The andesitic-to-rhyolitic Fuya Fuya volcano was constructed contemporaneously immediately to the west of Mojanda and produced two major rhyolitic plinian explosive eruptions, possibly associated with caldera formation. Fuya Fuya underwent edifice collapse less than 165,000 years ago, leaving a large horseshoe-shaped caldera open to the west. Subsequently, a new composite cone and dacitic lava domes were extruded inside the caldera. The youngest domes are unglaciated and of possible Holocene age.