A forearc basin is a sedimentary basin located between a subduction zone trench and the associated volcanic arc. These basins accumulate sediments eroded from the volcanic arc and the overriding plate, and they play a crucial role in understanding subduction processes, sedimentary environments, and the tectonic evolution of convergent margins.
Source Ingersoll, R. V. (1979). Evolution of the Late Cretaceous Forearc Basin, Northern and Central California. Geological Society of America Bulletin.