Chachimbiro

Geography & Climate

Chachimbiro is located in Ecuador, within the Northern Andean Volcanic Arc of the broader South America Volcanic Regions. Situated at 0.47° N, 78.29° W in the Northern Hemisphere, the volcano lies within a tropical climate zone. Standing at 4,106 meters above sea level, Chachimbiro 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

Chachimbiro 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 Chachimbiro, 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 dacite, an intermediate to silica-rich volcanic rock. This composition typically produces more viscous magma, leading to more explosive eruptions with ash columns and pyroclastic flows. Andesitic and dacitic magmas build pressure before erupting, which is why volcanoes with this rock chemistry are often associated with Plinian-style eruptions that can send ash tens of kilometers into the atmosphere and disrupt aviation across entire regions.

Eruption History Summary

Chachimbiro has 1 recorded eruption in the geological database, spanning from 3740 BCE to 3740 BCE. The most powerful recorded event was a severe eruption capable of regional ash fall and pyroclastic flows in 3740 BCE, reaching VEI 3 on the Volcanic Explosivity Index.

Significance

With a maximum recorded VEI of 3, Chachimbiro has produced eruptions capable of generating pyroclastic flows and significant ash fall in the surrounding area. While not among the largest eruptions globally, VEI 3 events pose serious hazards to local populations and can disrupt regional air travel.

GVP Reference Summary

The Chachimbiro volcanic complex lies about 25 km NW of the city of Ibarra. Late Pleistocene collapse of the andesitic Huanguillaro stratovolcano produced a 6.8 km3 debris-avalanche deposit and a 4-km-wide avalanche caldera open to the east that has largely been filled by lava domes, including the rhyodacitic Hugá dome. The avalanche deposit is overlain by three large ignimbrites and pyroclastic-flow deposits related to dome growth. The late Pleistocene-to-Holocene, NNE-trending, dacitic Chachimbiro-Pucará line of lava domes includes the Pitzantzi dome, which erupted about 5,700 years ago, producing an ash deposit that extends to the NW. Hot springs and thermal areas are present in the complex.

— Smithsonian Institution, Global Volcanism Program