What is created by subduction of one oceanic plate beneath another?

When one oceanic plate is subducted beneath another, significant geological features are formed as a result of this process. The subduction zone is characterized by two primary outcomes: the formation of volcanic island arcs and ocean trenches.

When the denser oceanic plate is pushed down into the mantle beneath the other plate, it causes the plate that is being subducted to melt and triggers volcanic activity. This volcanic activity can give rise to chains of volcanic islands, known as volcanic island arcs, which typically appear parallel to the trench created by the subduction process.

Additionally, the area where the oceanic plate is being forced down is marked by a deep trench at the ocean floor, known as an ocean trench. These trenches are some of the deepest parts of the ocean and delineate the boundary between the two plates.

Therefore, the correct answer encompasses both volcanic island arcs and ocean trenches, as both result from the subduction of one oceanic plate beneath another.