Mojanda

Geography & Climate

Mojanda is located in Ecuador, within the Northern Andean Volcanic Arc of the broader South America Volcanic Regions. Situated at 0.13° N, 78.27° W in the Northern Hemisphere, the volcano lies within a tropical climate zone. Standing at 4,263 meters above sea level, Mojanda towers above the alpine zone, where vegetation gives way to bare rock, snow, and ice for much of the year. The high elevation means the upper slopes experience significantly colder temperatures than surrounding lowlands. The volcanic landform is characterized as a composite, which describes the physical shape and structure of the volcanic edifice as observed from the surface.

Geological Context

Mojanda sits in a subduction zone, where one tectonic plate dives beneath another, creating intense heat and pressure that generates magma. Subduction zones are responsible for many of the world's most explosive volcanoes and deadliest eruptions. For communities in Ecuador near Mojanda, this tectonic setting means the volcano is capable of producing powerful explosive eruptions, pyroclastic flows, and lahars that can threaten populated areas within tens of kilometers of the summit. The dominant rock type is andesite / basaltic andesite, a dark, fine-grained volcanic rock that forms from rapidly cooling, low-viscosity lava. Basaltic eruptions tend to be less explosive and produce fluid lava flows that can travel long distances. While less immediately dangerous than explosive eruptions, basaltic lava flows can destroy structures and infrastructure in their path, and volcanic gases released during these eruptions can affect air quality over a wide area.

GVP Reference Summary

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.

— Smithsonian Institution, Global Volcanism Program