Which feature is a curved chain of volcanic islands and seamounts that forms parallel to the edge of a trench?

Which feature is a curved chain of volcanic islands and seamounts that forms parallel to the edge of a trench?

• A. Island Arc
• B. Passive Margin
• C. Oceanic Ridge
• D. Seamount

Answer: (A)

This concept centers on how subduction zones generate volcanic arcs. When one oceanic plate dives beneath another, fluids released from the subducting slab lower the melting point of the overlying mantle, producing magma that rises to form volcanoes. These volcanoes build a chain that lies roughly parallel to the trench marking the subduction boundary. Because the boundary and the motion of the plates are curved rather than perfectly straight, the resulting volcanic chain forms a curved arc, consisting of islands and seamounts. This is seen in many regions with oceanic-continental subduction, like the western Pacific. In contrast, a passive margin is a tectonically quiet transition with little volcanic activity; an oceanic ridge forms at a divergent boundary with new crust creation; a seamount is an isolated submarine volcano, not a continuous arc along a trench.

This concept centers on how subduction zones generate volcanic arcs. When one oceanic plate dives beneath another, fluids released from the subducting slab lower the melting point of the overlying mantle, producing magma that rises to form volcanoes. These volcanoes build a chain that lies roughly parallel to the trench marking the subduction boundary. Because the boundary and the motion of the plates are curved rather than perfectly straight, the resulting volcanic chain forms a curved arc, consisting of islands and seamounts. This is seen in many regions with oceanic-continental subduction, like the western Pacific. In contrast, a passive margin is a tectonically quiet transition with little volcanic activity; an oceanic ridge forms at a divergent boundary with new crust creation; a seamount is an isolated submarine volcano, not a continuous arc along a trench.