Island Arc
Island Arc - a chain of volcanic island over the subduction zone, occurring where the oceanic plate sinks beneath the ocean. As typical of modern island arcs include the Aleutian, Kuril Islands, Mariana Islands, and many other archipelagos. The Japanese islands are also often called the island arc, but their foundation is very old and in fact they are formed by several different periods complexes of island arcs, so that the Japanese islands are microcontinents.
Island arc formed by the collision of two oceanic plates. This is one of the plates is lower and is absorbed into the mantle. The upper plate is formed island arc volcanoes. Curved side of the island arc is directed toward absorbed by the slab. On this side are a deep trough and preddugovy deflection.
For the island arc is located back-arc basins (typical examples: the Sea of Okhotsk, South China Sea, etc.) which can also occur spreading.