page_title: Mariana Plate
section_title: Eastern Convergent Boundary
hierarchical_section_title: Mariana Plate / Tectonic Behavior / Eastern Convergent Boundary
caption_attribution_description: English: Mariana Trench and Trough
context_page_description: The Mariana Plate is a micro tectonic plate located west of the Mariana Trench which forms the basement of the Mariana Islands which form part of the Izu-Bonin-Mariana Arc. It is separated from the Philippine Sea Plate to the west by a divergent boundary with numerous transform fault offsets. The boundary between the Mariana and the Pacific Plate to the east is a subduction zone with the Pacific Plate subducting beneath the Mariana. This eastern subduction is divided into the Mariana Trench, which forms the southeastern boundary, and the Izu-Ogasawara Trench the northeastern boundary. The subduction plate motion is responsible for the shape of the Mariana plate and back arc.
context_section_description: 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  This eastern subduction is divided into the Mariana Trench, which forms the southeastern boundary, and the Izu-Ogasawara Trench the northeastern boundary. The Izu-Ogasawara Trench and Mariana subduction zones are traveling at different rates. While the northern section of the Izu-Ogasawara Trench plate is subducting at 44 mm/yr, the southern section subducts at 14 mm/yr. The subducting Pacific Plate dips at about 10 degrees and directed 83 degrees west of north. The northern subduction zone is expanding by rifting while the southern contains a strike slip fault. Seismologists have been studying how the subducting slabs underneath the Mariana island arc are entering the lower mantle and being redirected horizontally, deflecting off the upper to lower mantle transition zone.
caption: Mariana Plate Boundary. 1 is West Mariana Ridge, 2 is Mariana Trough, 3 is Mariana Arc, 4 is Mariana Fore-Arc,  5 is Mariana Trench
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