Tremors and low-frequency earthquakes (LFEs), which occur in the plate interface, can provide useful information about the state of aseismic stress transfer in mega-earthquake fault zones. We estimated the distribution of triggered LFEs in the subducted plate interface. Specifically, we detected LFEs in the Ryukyu Trench triggered by the surface waves of large teleseismic earthquakes by using the waveform records of broadband and short-period seismometers installed in the Ryukyu Arc. We selected a total of 45 teleseismic earthquakes with magnitudes of more than 7.5, which occurred between 2004 and 2017, for the analysis. We could detect the triggered LFEs for five teleseismic earthquakes. Then, we determined the hypocenters of LFEs by using the relative arrival times of LFEs for each station. The LFEs were distributed in the south of Okinawa Island and the Yaeyama area. Moreover, they were distributed around the source fault of the slow slip events. These were almost the same as and concentrated near to the locations of the most active LFE clusters accompanying very low-frequency earthquakes, suggesting higher sensitivity of inducing LFEs near these clusters. This indicates that the LFEs accompanying VLFEs are activated by stress acceleration in the Yaeyama and Okinawa areas.

发生在板块界面的震颤和低频地震 (LFE) 可以提供有关特大地震断层带中抗震应力传递状态的有用信息。我们估计了俯冲板块界面中触发 LFE 的分布。具体而言，我们利用安装在琉球弧上的宽带和短周期地震仪的波形记录，在琉球海沟中探测到由远震大地震面波触发的LFE。我们选择了 2004 年至 2017 年间发生的 45 次超过 7.5 级的远震地震进行分析。我们可以检测到五次远震地震的触发 LFE。然后，我们通过使用每个台站 LFE 的相对到达时间来确定 LFE 的震源。LFE 分布在冲绳岛南部和八重山地区。此外，它们分布在慢滑移事件的源断层周围。这些与伴随极低频地震的最活跃的 LFE 集群的位置几乎相同并集中在附近，这表明在这些集群附近诱导 LFE 的敏感性更高。这表明伴随着 VLFE 的 LFE 在八重山和冲绳地区被应力加速激活。