The West Philippine Basin, is the oceanic crust located underneath the western part of the Philippine Sea. It was formed during the early Oligocene epoch.[1] To its southwest is the Philippine Trench, and to its east is the Kyushu–Palau Ridge.[2] The West Philippine Basin is deeper and older than the eastern basins and has crustal heat-flow values approaching that of old oceanic crust.[3][4] It is roughly bisected by the Central Basin Fault zone which comprises a band of high relief running from the northwest corner to the Kyushu–Palau Ridge near 14°N. Characterized by the presence of several submarine plateaus (Benham Rise and Anami and Oki-Daito Ridges).