What is an Island Arc? A group of volcanic islands, usually situated in a curving arch-like pattern that is convex toward the open ocean, having a deep trench or trough on the convex side and usually enclosing a deep basin on the concave side; formed by volcanic activity associated with oceanic plate subduction at convergent plate margins Also known as volcanic arc.
Simple Version A chain of volcanic activity is present. When the volcanos erupt the magma goes into the water. This builds up and creates a island thats in the water but peaks out of the ocean. This is known as Island Arcs