Global Volcanism Program | Image GVP-10077
The 7 x 10 km Coatepeque caldera forms a dramatic vista from the summit of Santa Ana volcano. The caldera was formed by collapse of a group of stratovolcanoes immediately east of Santa Ana volcano during a series of major explosive eruptions between about 70,000 and 57,000 years ago. Post-caldera eruptions included the formation of basaltic cinder cones and lava flows near the western margin of the caldera and the extrusion of rhyodacitic lava domes, including Cerro la Isla, the island at the W side of the caldera lake.
Photo by Lee Siebert, 2002 (Smithsonian Institution).