Global Volcanism Program | Image GVP-07734
Santa Ana volcano, seen in the distance more than 30 km to the north, underwent catastrophic edifice collapse during the late Pleistocene. This produced a massive, highly mobile debris avalanche that deposited the boulders in the foreground and formed the small hills in the middle distance. The larger hill at the left is a kipuka formed by rocks of the older Bálsamo formation, which were surrounded by the avalanche. This avalanche was one of the largest known in Central America and traveled nearly 50 km from the volcano.
Photo by Lee Siebert, 1999 (Smithsonian Institution).