Rock exhumation and surface uplift over subduction zones require part of the stresses to cause crustal thickening within the wedge and/or through basal accretion. Although accumulated elastic strain around subduction zones is released through megathrust earthquakes and related aftershocks, these large events often result in no permanent forearc surface uplift. Nevertheless, energy is also released by more frequent and dispersed background seismicity, a signal that is often overlooked. Here we investigate the variability of this energy along the Peru–Chile and Japan margins. We find that the pattern of background seismicity correlates with the margin-parallel long-wavelength wedge geometry and with published estimates of geologic-timescale coastal uplift. Furthermore, the orientation of the principal stresses related to these background events is consistent with contractional seismicity, predominantly located at the deep (30–60 km) plate interface depth. Taken together, these results indicate that background seismicity is associated with crustal thickening during the megathrust interseismic period. This mechanism may contribute substantially to the surface uplift of subduction margins over geologic timescales.

俯冲带上的岩石折返和地表隆起需要部分应力来导致楔形内的地壳增厚和/或通过基底增生。尽管俯冲带周围累积的弹性应变通过大逆冲地震和相关余震释放，但这些大型事件通常不会导致永久的弧前表面隆起。然而，更频繁和分散的背景地震也会释放能量，这是一个经常被忽视的信号。在这里，我们调查了这种能量在秘鲁-智利和日本边缘的变化。我们发现背景地震活动的模式与边缘平行的长波长楔形几何形状以及已发表的地质时间尺度海岸隆起的估计相关。此外，与这些背景事件相关的主应力方向与收缩地震活动一致，主要位于深部（30-60 km）板块界面深度。综上所述，这些结果表明，背景地震活动与大逆冲震间期的地壳增厚有关。这种机制可能对地质时间尺度上俯冲边缘的地表抬升有很大贡献。