A volcanic island arc is formed when?

A volcanic island arc is formed when an oceanic tectonic plate subducts beneath another oceanic plate. This subduction process leads to the melting of the subducted plate, resulting in magma that rises to the surface and creates volcanic islands. These islands typically form in a curved chain, parallel to the trench created by the subduction zone. Over time, repeated volcanic activity can build up a significant landmass above sea level.