We examined seismic moment release rates as estimated from deep low-frequency tremors at episodic tremor and slip (ETS) zones on the plate interface in the Nankai subduction zone. Excluding periods with long-term slow slip events, we observe no clear temporal variation in the seismic moment release rate in the Tokai, the northern Kii, or Shikoku regions. We also find no variation in the seismic moment release rate related to the 2011 Tohoku earthquake in the southern or central Kii region. These findings imply that the 2011 Tohoku earthquake has not affected slow slip activities in the Nankai subduction zone. For the southern and central Kii regions, a long-term decrease in the seismic moment release rate with time is apparent, irrespective of the occurrence of the 2011 Tohoku earthquake, suggesting that frictional properties on slip planes at the ETS zone on the plate interface have varied over time.

中文翻译：

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从南海俯冲带深部低频震颤推断慢滑移地震矩释放率的时间变化

我们研究了根据南海俯冲带板块界面上的间歇性震颤和滑动 (ETS) 带的深低频震颤估计的地震矩释放率。排除长期缓慢滑动事件的时期，我们观察到东海、纪伊北部或四国地区的地震矩释放率没有明显的时间变化。我们还发现纪伊南部或中部地区与 2011 年东北地震相关的地震矩释放率没有变化。这些发现意味着 2011 年的东北地震并未影响南海俯冲带的慢滑移活动。对于纪伊南部和中部地区，无论 2011 年东北地震是否发生，地震矩释放率随时间的长期下降是明显的，