The Galeras volcanic complex is located in the Colombian segment of the South American Andes mountains. The Andes in Colombia are the result of a collision between the Panamanian tectonic block with South America, which detached part of the South American plate from the continent. This segment was pushed northward and upward, and this thrusting (in addition to the subduction of part of the Nazca plate under the Colombian block) created the Northern Andes. Galeras is located near a northwest-dipping thrust fault zone that resulted from this collision.