which arc is a line of volcanoes on an oceanic plate
continental volcanic arcs
title: Volcanic arc text: Volcanic arc A volcanic arc is a chain of volcanoes formed above a subducting plate, positioned in an arc shape as seen from above. Offshore volcanoes form islands, resulting in a volcanic island arc. Generally, volcanic arcs result from the subduction of an oceanic tectonic plate under another tectonic plate, and often parallel an oceanic trench. The oceanic plate is saturated with water, and volatiles such as water drastically lower the melting point of the mantle. As the oceanic plate is subducted, it is subjected to greater and greater pressures with increasing depth. This pressure squeezes water out of the title: Island arc text: Island arc Island arcs are long chains of active volcanoes with intense seismic activity found along convergent tectonic plate boundaries (such as the Ring of Fire). Most island arcs originate on oceanic crust and have resulted from the descent of the lithosphere into the mantle along the subduction zone. They are the principal way by which continental growth is achieved. Island arcs can either be active or inactive based on their seismicity and presence of volcanoes. Active arcs are ridges of recent volcanoes with an associated deep seismic zone. They also possess a distinct curved form, a chain of active title: Volcanic arc text: are smaller and more lush than the recently created (400,000 years ago) Hawaii island itself, which is more rocky. Hotspot volcanoes are also known as "intra-plate" volcanoes, and the islands they create are known as Volcanic Ocean Islands. Volcanic arcs do not generally exhibit such a simple age-pattern. There are two types of volcanic arcs: In some situations, a single subduction zone may show both aspects along its length, as part of a plate subducts beneath a continent and part beneath adjacent oceanic crust. Volcanoes are present in almost any mountain belt, but this does not make it a volcanic title: Continental arc text: thus returns to the continental crust, while another part would form new mantle material. The concepts "island arc", "volcanic arc", "oceanic arc" and "continental arc" may be confused: In some cases, both a continental arc and oceanic arc can form along the strike of a single subduction zone (e.g. Aleutian Islands and Alaska Peninsula). Continental arc A continental arc is a type of volcanic arc occurring as an "arc-shape" topographic high region along a continental margin. The continental arc is formed at an active continental margin where two tectonic plates meet and a subduction zone develops. The magmatism and petrogenesis title: Volcanic arc text: plate and introduces it to the mantle. Here the mantle melts and forms magma at depth under the overriding plate. The magma ascends to form an arc of volcanoes parallel to the subduction zone. These should not be confused with hotspot volcanic chains, where volcanoes often form one after another in the middle of a tectonic plate, as the plate moves over the hotspot, and so the volcanoes progress in age from one end of the chain to the other. The Hawaiian Islands form a typical hotspot chain; the older islands (tens of millions of years old) to the northwest