Volcanic island

A volcanic island is land built above surrounding water by volcanic activity, often beginning with eruptions on the seafloor.

Submarine volcano: A volcano that erupts beneath the ocean or another body of water. Many volcanic islands begin as submarine volcanoes whose eruptions eventually reach the surface.
Hawaiian Islands: An archipelago in the central Pacific formed primarily by volcanism above the Hawaiian hotspot. The island chain records how hotspot volcanism builds islands as the Pacific Plate moves.
Plate tectonics: The theory that Earth’s outer shell consists of moving plates whose interactions shape its surface. Plate motion determines where many island-building volcanoes form and how their chains develop.
Coral atoll: A ring-shaped coral reef or island enclosing a lagoon, often formed around a subsiding volcanic island. Reefs can remain near sea level as a volcanic island subsides and erodes away.
Seamount: An underwater mountain, commonly formed by volcanic activity, that does not reach the ocean surface. A growing seamount can become an island if volcanic construction raises it above sea level.
Aleutian Islands: A chain of volcanic islands extending from Alaska toward Russia along the Aleutian subduction zone. The Aleutians illustrate island construction above a convergent plate boundary.
Subduction: The descent of one tectonic plate beneath another into the mantle. Subduction supplies magma for many volcanic arcs composed of islands.
Island arc: A curved chain of islands formed by volcanism above a subduction zone. Volcanic islands can be individual members of a larger island arc.
Hotspot: A region of persistent volcanism caused by mantle upwelling or other long-lived heat sources. Hotspots build island chains as tectonic plates move over persistent volcanic sources.
Lesser Antilles: An arc of islands in the eastern Caribbean formed largely by subduction-related volcanism. Its volcanic islands exemplify an arc created where oceanic crust descends beneath another plate.

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