Global Volcanism Program | Image GVP-04004
The hilly terrain in the foreground is part of a debris-avalanche deposit that extends 25 km from the summit of Pacaya volcano to the Pacific coastal plain. Portions of the avalanche rode more than 100 m up the side of the ridge in the background before coming to rest on the valley floor. The avalanche was accompanied by a pyroclastic surge whose deposits overlie the proximal 10 km of the avalanche deposit. The collapse is bracketed by tephra layers dated at about 1550 and 600 years ago.
Photo by Lee Siebert, 1988 (Smithsonian Institution).