What is an island arc?
Where oceanic plates collide, subduction leads to increased friction and melting. The less dense material begins to rise through the crust, creating a series of volcanic islands.
Radioactive elements beneath the crust cause intense heating, often away from plate boundaries. As the volcano breaks through the crust and crust moves, an arc is formed.
As plates diverge, magma is forced to the surface. After subsequent underwater eruptions, eventually island arcs are formed along ridges, such as in the Mid Atlantic.
As continental plates collide, enormous pressure is exerted and folding occurs. Where folding occurs in coastal locations, some land can be cut off by the sea leading to arc formation.
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