Major caldera systems of the Alaska/Aleutian subduction zone system

The Alaska-Aleutian Subduction Zone hosts the highest concentration of active volcanoes in the U.S. (orange triangles). Of these, several are caldera systems, with three notable examples highlighted (red triangles). Photos of Okmok, Fisher, and Aniakchak Calderas are shown in the lower panels. Digital shaded-relief map of Alaska from the USGS. Caldera images courtesy of AVO/USGS.