The 2011 Tohoku-Oki great earthquake increased the difficulty of evaluating the long-term probability of seismic activity along the Japan Trench because of the unknown impact of the unprecedentedly large slip. In this study, the long-term activity of “Miyagi-ken-Oki earthquakes”, an M > 7 earthquake sequence off Miyagi Prefecture, located at the edge of the source area of the Tohoku-Oki earthquake was simulated. We conducted numerical simulations of earthquake generation cycles based on the rate- and state-dependent friction law representing the stress accumulation and release process on the plate interface. We also validated the results based on analyses of observational data, including time intervals and afterslip distributions for the previous Miyagi-ken-Oki earthquakes. The simulation results were then compared with repeating-earthquake-derived interplate slip observations over 30 years. The results showed that the spatial and temporal characteristics of aseismic slips on the plate interface near the M > 7 Miyagi-ken-Oki source were qualitatively reproduced. The time interval between the M ~ 9 earthquake and the first M > 7 earthquake is shorter than the average recurrence interval of M > 7 earthquakes during the latter stage of each M ~ 9 earthquake cycle. In contrast, the interval between the first and the second M > 7 earthquakes is the longest in each M ~ 9 earthquake cycle. The time intervals of the M > 7 earthquakes fluctuated in the early stage compared to those in the latter stage of the M ~ 9 earthquake cycle. These characteristics were associated with the extent of the locked and afterslip areas in and around the source. Hence, monitoring the spatio-temporal distribution of the slip rate in and around the source area during the preparation process of earthquakes occurring in the downdip area off Miyagi Prefecture is very important to assess whether the next M > 7 earthquake is approaching. Furthermore, earthquake cycle simulations combined with earthquake and slow slip monitoring can provide meaningful insights for long-term assessments of great interplate earthquakes.

2011年东北冲大地震增加了评估日本海沟沿线地震活动长期概率的难度，因为史无前例的大滑动影响未知。在这项研究中，模拟了“宫城县冲地震”的长期活动，这是宫城县附近的7级地震序列，位于东北冲地震震源区的边缘。我们根据代表板界面应力积累和释放过程的速率和状态相关摩擦定律对地震发生周期进行了数值模拟。我们还根据观测数据分析验证了结果，包括之前宫城县冲地震的时间间隔和后滑分布。然后将模拟结果与 30 年来重复地震衍生的板间滑动观测结果进行比较。结果表明，定性地再现了 M > 7 Miyagi-ken-Oki 震源附近板块界面上地震滑移的时空特征。～9级地震与首次7级以上地震的时间间隔短于每个8～9级地震周期后期7级以上地震的平均复发间隔。相比之下，第一次和第二次7级地震之间的间隔是每个9级地震周期中最长的。与 9 级地震周期的后期相比，> 7 级地震的时间间隔在早期出现波动。这些特征与震源内部和周围的锁定区域和后滑区域的范围有关。因此，监测宫城县近海下倾地区地震孕育过程中震源区及其周边滑移率的时空分布，对于评估下一次7级以上地震是否即将来临具有重要意义。此外，地震周期模拟与地震和慢滑动监测相结合可以为板间大地震的长期评估提供有意义的见解。监测宫城县近海下倾地区地震孕育过程中震源区及其周边滑移率的时空分布，对于评估下一次7级以上地震是否即将来临非常重要。此外，地震周期模拟与地震和慢滑动监测相结合可以为板间大地震的长期评估提供有意义的见解。监测宫城县近海下倾地区地震孕育过程中震源区及其周边滑移率的时空分布，对于评估下一次7级以上地震是否即将来临非常重要。此外，地震周期模拟与地震和慢滑动监测相结合可以为板间大地震的长期评估提供有意义的见解。