Island Arc Formation

Island arc formation is the process by which a curved chain of volcanic islands rises above sea level where one oceanic plate subducts beneath another, as water carried down with the sinking slab lowers the melting point of the overlying mantle wedge and generates the magma that feeds the arc chain of volcanoes. The curvature of the arc traces the intersection of the roughly spherical subducting slab with the Earth surface, and the Aleutian, Mariana and Japanese island arcs are among the clearest expressions of the process still active today.