It is separated from the Philippine Sea plate to the west by a divergent boundary with numerous transform fault offsets.

The Mariana Islands consist of volcanoes that are active and dormant[4] and are made up of volcanic and sedimentary rocks from the Pleistocene.

[3] The tectonic plate is approximately 100 km thick and converging to the east at a rate of 50–80 mm/yr with the Pacific plate subducting at 60–100 mm/yr[8] This eastern subduction is divided into the Mariana Trench, which forms the southeastern boundary, and the Izu–Ogasawara Trench the northeastern boundary.

[6] Due to the back arc spreading in the Mariana Trough the islands are moving east while the Philippine Sea plate is staying almost stationary.

[4] Since there is volcanism happening on the Mariana back arc ridge and basin, this system could continue to grow but combining the rate of separation from the Philippine plate along with the subduction destroying the Mariana plate it is possible this microplate could eventually dissipate.

[11] The collision of aseismic ridges and the axis of the trench explain how the plate curvature is evolving.