Whether tectonic convergence at subduction zones is accommodated predominantly through seismic or aseismic deformation, the former potentially generating large earthquakes, varies considerably between subduction margins. This margin‐scale variability has previously been linked to overriding plate deformation, trench migration, and their influence on the plate interface stress state. While these processes are linked to mantle‐scale dynamics, it is unclear how such dynamics influence interface stress. We systematically analyze the interface stress state in a suite of 2‐D thermo‐mechanical subduction models, where slabs display a range of morphologies that arise from diverse multiscale interactions with adjacent mantle and the overriding plate. We demonstrate that the thickness of the interface layer varies dynamically, in response to Poiseuille flow induced by slab bending or unbending, leading to associated effects on interface shear stress at typical seismogenic depth. Lower shear stress occurs when slab unbending is significant, which is commonly associated with trench retreat and draping of the slab as it impinges on the higher‐viscosity lower‐mantle. Conversely, higher shear stress is associated with limited slab unbending, which is promoted by negligible trench migration and vertically subducting slabs. We conclude that the diversity of slab dynamics may cause large variations in interface stress state between and maybe within margins. This is an additional variable that potentially controls seismogenic behavior, and we compare broad stress estimates for Circum‐Pacific margins to previous studies. Although predicted shear stress varies with observed seismogenic behavior, more detailed constraints on stress state are needed to test for correlation.

中文翻译：

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俯冲带动力学对界面剪切应力的影响以及与地震作用的潜在关系

无论俯冲带的构造收敛主要是通过地震变形还是抗震变形来适应，前者潜在地会引发大地震，在俯冲带边缘之间差异很大。以前，这种边缘尺度的变化与覆盖板变形，沟槽迁移及其对板界面应力状态的影响有关。虽然这些过程与地幔尺度动力学有关，但尚不清楚这些动力学如何影响界面应力。我们在一套二维热力俯冲模型中系统地分析了界面应力状态，其中平板显示了一系列形态，这些形态是由于与邻近地幔和上覆板的多种多尺度相互作用而产生的。我们证明了界面层的厚度是动态变化的，响应板弯曲或未弯曲引起的泊瓦流动，从而在典型的地震发生深度对界面剪切应力产生相关影响。当板的未弯曲很大时，会产生较低的剪切应力，这通常与沟槽后退和板的悬垂有关，因为它会冲击较高粘度的下地幔。相反，较高的剪应力与有限的板坯未弯曲有关，这是由可忽略的沟槽迁移和垂直俯冲板坯引起的。我们得出的结论是，平板动力学的多样性可能会导致边界之间甚至边界内的界面应力状态发生较大变化。这是一个可能控制地震行为的附加变量，我们将环太平洋边缘的广泛应力估算值与以前的研究进行了比较。