[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).
Envisioned a N–S trending transform fault (connecting two ridges, the Kula Pacific Ridge and the Philippine Ridge/Central Basin Fault as turning into a subduction (the proto-Mariana Trench) zone following a change in the Pacific plate's motion from NNW to WNW during the Eocene.
In this model, the basin is originally a part of the Pacific plate which was isolated during the kinematic reorganization 43 Ma.
First proposed by Karig (1971), shows the WPB as forming by back-arc spreading behind the Oki-Daito Ridge starting the Eocene.