Volcanic islands emerge from the ocean through processes that span millions of years. Understanding their formation reveals fundamental truths about Earth's geology and the forces that shape our planet.
Most volcanic islands form at tectonic plate boundaries, where oceanic crust is created or destroyed. The "Ring of Fire" around the Pacific is lined with volcanic island chains—Japan, the Philippines, Indonesia—formed by subduction.
Others form over "hotspots"—stationary plumes of hot material rising from deep within the mantle. As plates move over these hotspots, chains of islands form. Hawaii is the classic example: a conveyor belt of islands, with the oldest and most eroded to the northwest.