Global Volcanism Program | Image GVP-04053
Coatepeque caldera, its eastern side filled by a caldera lake, was formed by collapse of a group of stratovolcanoes immediately east of Santa Ana volcano. The eastern caldera rim rises about 250 m above the lake surface. Post-caldera eruptions included the formation of basaltic cinder cones and flows near the western margin of the caldera and the extrusion of a half dozen rhyodacitic lava domes (such as the one forming La Isla at the right) along a NE-SW line near the caldera-lake margins.
Copyrighted photo by Dianne Neilson, 1972 (courtesy of Richard Stoiber, Dartmouth College).