A usually curved chain of volcanoes occurring on the overriding tectonic plate of a subduction zone, formed by magma that rises from the melting of the descending plate.
A curved chain of volcanoes in the overriding tectonic plate of a subduction zone. Volcanic arcs form as the result of rising magma formed by the melting of the downgoing plate. They are curved because of the curvature of the Earth. The Andes mountains form a volcanic arc.