interarc basin

A back-arc basin is a submarine basin that forms behind an island arc, typically found near the convergence of two tectonic plates, such as along the western Pacific Ocean margin. These basins are created through a process called back-arc spreading. This occurs when one tectonic plate subducts under another, causing magma to rise and create rifts in the overlying plate's crust. As more magma surfaces, spreading centers develop, widening the seafloor behind the trench.1

Examples of back-arc basins include the Sea of Japan and the Mariana Trough. These regions are notable for significant hydrothermal activity and diverse biological communities around deep-sea vents. The formation and behavior of these basins are integral to the broader theory of plate tectonics.12