Numerous studies have reported that surface hydrological loading can seasonally modulate seismicity rates at crustal depths. For example, substantial winter snow accumulation occurs across the Japanese Islands, and these snowy regions appear to have seasonally modulated the occurrence of previous large inland earthquakes. Therefore, it is important to investigate the impact of seasonal stress changes on crustal seismicity to deepen our understanding of earthquake generation. Here we constrain seasonal changes in the surface load across northeastern Japan using Global Navigation Satellite System surface displacements and evaluate the potential relationship between temporal trends in inland seismicity and estimated seasonal stress changes. The spatial distribution of the seasonal surface load is consistent with snow depth along the Sea of Japan. The inland seismicity beneath northeastern Japan is modestly modulated by the seasonal stress changes that are induced by the annual snow load. However, this seasonal response is weaker than that in other regions. This weak modulation may be due to the small surface-load-induced stress perturbation relative to the long-term-averaged stressing rate and/or the limited presence of crustal fluids to trigger seismicity in Japan.

中文翻译：

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雪荷驱动的日本东北部地壳地震活动的季节调制

许多研究表明，地表水文负荷可以季节性地调节地壳深处的地震活动率。例如，日本列岛冬季出现大量积雪，这些积雪地区似乎季节性地调节了之前内陆大地震的发生。因此，研究季节性应力变化对地壳地震活动的影响对于加深我们对地震发生的认识具有重要意义。在这里，我们使用全球导航卫星系统表面位移来限制日本东北部表面载荷的季节性变化，并评估内陆地震活动的时间趋势与估计的季节性应力变化之间的潜在关系。季节性表面负荷的空间分布与日本海沿岸的积雪深度一致。日本东北部下方的内陆地震活动受到年雪荷载引起的季节性应力变化的适度调节。然而，这种季节性反应弱于其他地区。这种弱调制可能是由于相对于长期平均应力速率而言，表面载荷引起的应力扰动较小和/或触发日本地震活动的地壳流体的存在有限。