Final answer:
When two oceanic plates converge and one is subducted, an arc of volcanic islands can form due to the rise of magma created by the melting subducted plate.
Step-by-step explanation:
When two oceanic plates converge, one typically subducts beneath the other due to differences in their densities. This occurs at what geologists call a subduction zone. At such a boundary, the subducting plate descends into the mantle, leading to high-pressure and temperature conditions that may result in the melting of the plate's material. This process can create magma that rises and contributes to volcanic activity. Consequently, one outcome of this tectonic interaction is the formation of an arc of volcanic islands. The released magma as the subducted plate melts can penetrate through the crust, eventually erupting on the surface to form an island arc.
These island arcs are a direct result of the intense geological processes occurring at subduction zones. As the descending plate melts, it not only creates magma but also triggers volcanic activity along the overriding plate, giving birth to new volcanic islands. An example of this process can be seen in the Pacific Ocean's 'Ring of Fire', where numerous island arcs have formed due to oceanic plate convergence and subduction. The creation of an island arc is one of the key ways in which our planet recycles its crustal materials over geological timescales.