Volcanic arcs, either normal or island, are volcanic zones created by what?
Volcanic arcs, whether normal or island, are volcanic zones created by subduction processes. Subduction occurs when one tectonic plate is forced beneath another, typically at convergent plate boundaries where two plates collide. In these zones, the subducting plate sinks into the mantle, which generates intense heat and pressure leading to volcanic activity.
Normal volcanic arcs form when an oceanic plate subducts beneath another oceanic plate or a continental plate. As the subducting plate sinks, it releases water and other volatile substances trapped within its rocks. These volatiles rise and mix with the mantle, lowering its melting point and causing magma to form. This magma eventually rises through the overlying plate to the surface, resulting in the creation of a volcanic arc.
Island volcanic arcs, on the other hand, are formed when an oceanic plate subducts beneath a continental plate. The subduction of the denser oceanic plate creates magma, which rises and forms a chain of volcanoes along the edge of the continental plate. These volcanoes often form on or near islands, hence the name island volcanic arcs.
Overall, the formation of volcanic arcs is closely linked to the process of subduction, where one tectonic plate is forced beneath another, leading to the melting of rocks and subsequent volcanic activity.