The subduction region is referred to as the subduction zone. When a plate slips underneath another, it forms a trench. Earthquakes resulting from the plate panelling often result in magma spilling across the underwater volcano trench. Island arcs are vast chains of active volcanoes with strong seismicity located along the converging tectonic plate borders. Much of the islands arcs emerge from the oceanic crust and also have originated from fall of the lithosphere into the mantle across the subduction zone. In the Andes mountain range, Under the South American plate the Nazca plate is subducting.