Two tectonic plates converge at subduction zones where the subducting plate bends. Flexural bending of a subducting plate at a trench results in pervasive normal faulting, providing conduits for plate hydration and influencing the water budget and seismic behavior of the plate interface. 2-D plate bending simulations have demonstrated high strains due to strong bending may result in loss of strength of the lithosphere and intraplate earthquakes near the trench axis. However 3-D plate bending deformation may affect the along-strike slab pull force, especially when the deflection changes along the trench. Here we simulated the 3-D plate bending deformation and calculated bending stresses, and brittle failure of the Pacific plate at the Mariana Trench. We find that both the plate deflection and the yield zone depth (~16–20 km) increases from the northern to southern Mariana Trench. The water flux in the plate at the southern Mariana Trench is estimated to be about 15% greater than that of the northern Mariana Trench. By comparing with 2-D models, we further find that the 2-D approaches may undereastimate the yield zone depth as they ignored the along-trench effects of plate deflection. The new results provide a self-consistent framework for interpretation of the observed surface normal faults, extensional earthquakes, and the inferred hydration of the subducting plate as constrained by seismic velocity anomalies.

两个构造板块在俯冲板块弯曲的俯冲带汇聚。俯冲板块在海沟处的弯曲弯曲导致普遍的正断层，为板块水化提供管道并影响板块界面的水收支和地震行为。二维板弯曲模拟表明，由于强弯曲导致的高应变可能导致岩石圈强度损失和海沟轴附近的板内地震。然而，3-D 板弯曲变形可能会影响沿走向的板坯拉力，特别是当挠度沿沟槽发生变化时。在这里，我们模拟了 3-D 板弯曲变形并计算了弯曲应力，以及马里亚纳海沟太平洋板的脆性破坏。我们发现，从马里亚纳海沟的北部到南部，板块偏转和屈服区深度（~16-20 公里）都在增加。马里亚纳海沟南部板块中的水通量估计比马里亚纳海沟北部的水通量高约 15%。通过与二维模型的比较，我们进一步发现二维方法可能低估了屈服区深度，因为它们忽略了板挠曲的沿沟槽效应。新结果为解释观测到的地表正断层、伸展地震和推断的受地震速度异常约束的俯冲板块的水合作用提供了一个自洽的框架。通过与二维模型的比较，我们进一步发现二维方法可能低估了屈服区深度，因为它们忽略了板挠曲的沿沟槽效应。新结果为解释观测到的地表正断层、伸展地震和推断的受地震速度异常约束的俯冲板块的水合作用提供了一个自洽的框架。通过与二维模型的比较，我们进一步发现二维方法可能低估了屈服区深度，因为它们忽略了板挠曲的沿沟槽效应。新结果为解释观测到的地表正断层、伸展地震和推断的受地震速度异常约束的俯冲板块的水合作用提供了一个自洽的框架。