Eruptions from Pacaya, one of Guatemala's most active volcanoes, are frequently visible from Guatemala City, the nation's capital. This complex basaltic volcano was constructed just outside the southern topographic rim of the 14 x 16 km Pleistocene Amatitlán caldera. A cluster of dacitic lava domes occupies the southern caldera floor. The post-caldera Pacaya massif includes the ancestral Pacaya Viejo and Cerro Grande stratovolcanoes and the currently active Mackenney stratovolcano. Collapse of Pacaya Viejo between 600 and 1500 years ago produced a debris-avalanche deposit that extends 25 km onto the Pacific coastal plain and left an arcuate somma rim inside which the modern Pacaya volcano (Mackenney cone) grew. A subsidiary crater, Cerro Chino, was constructed on the NW somma rim and was last active in the 19th century. During the past several decades, activity has consisted of frequent strombolian eruptions with intermittent lava flow extrusion that has partially filled in the caldera moat and armored the flanks of Mackenney cone, punctuated by occasional larger explosive eruptions that partially destroy the summit of the growing young stratovolcano.
The Volcán de Pacaya massif rises above skyscrapers of the capital city of Guatemala, located only 30 km to the north. The rounded, forested lava dome of Cerro Grande forms the 2560 m high point at the left. The twin peak at the right is the historically active vent of Pacaya, with the right-hand summit being MacKenney cone, which has been active since 1965. The modern cone was constructed within an arcuate caldera whose rim forms the ridge on either side. Eruptions of Pacaya are often visible from Guatemala City.
Photo by Bill Rose, 1989 (Michigan Technological University).
Last updated 2019-12-16 17:30:03