Subduction of rough seafloor and seamounts is thought to impact a broad range of geodynamic processes, including megathrust slip behaviour, forearc fluid flow and long-term structural evolution in the overriding plate. Although there are many conceptual models describing the effects of seamount subduction, our quantitative and mechanistic understanding of the underlying deformation and fluid processes remains incomplete. Here we investigate the interplay between sediment consolidation, faulting and the evolution of stress and pore fluid pressure in response to seamount subduction, using a numerical model that couples mechanical and hydrological processes and is constrained by laboratory and field observations. Our results show that subducting topography drives marked spatial variations in tectonic loading, sediment consolidation and megathrust stress state. Downdip of a subducting seamount on its leading flank, enhanced compression and drainage lead to large fault-normal stress and overconsolidated wall rocks. A stress shadow in the seamount’s wake leads to anomalously high sediment porosity. These variations help explain observed patterns of megathrust slip, with earthquakes and microseismicity favoured at the downdip edge of seamounts and aseismic or slow slip in the updip stress shadow.

俯冲粗糙的海底和海山被认为会影响广泛的地球动力学过程，包括大推力滑移行为，前臂流体流动以及上覆板块的长期结构演化。尽管有许多描述海山俯冲作用的概念模型，但我们对潜在变形和流体过程的定量和力学理解仍然不完整。在这里，我们使用耦合机械和水文过程的数值模型，并受实验室和现场观测的约束，研究沉积物固结，断层与响应海山俯冲而产生的应力和孔隙流体压力之间的相互作用。我们的结果表明，俯冲形貌驱动了构造载荷的明显空间变化，沉积物固结和大推力应力状态。俯冲海山在其前翼下降，加强了压缩和排水，导致断层法向应力过大，围岩超固结。海山尾部的应力阴影导致异常高的沉积物孔隙度。这些变化有助于解释观测到的特大推力滑移模式，其中海山的下倾边缘有利于地震和微地震，而上倾应力阴影中则有利于地震或缓滑。