摘要：We evaluated the long-term strain rate by using continuous global navigation satellite system data of GEONET and compared it with seismicity activation between 1996 and 2017 near Iriomote Island, south Ryukyu arc.We analyzed the seismicity by using the epidemic-type aftershock sequence model to detect the timing when the seismicity had changed.The results revealed that the long-term shear strain rate had increased on around 2002 and around 2013, and this was accompanied by an increase in seismicity in both 2002 and 2013.The change in the shear strain rate in 2002 could be explained by the crustal movement induced by the 2002 afterslip in the area west of Iriomote Island.The change in the shear strain rate in 2013 could be explained by the post-seismic crustal movement induced by the dike intrusion that occurred during the earthquake swarm in the Okinawa Trough in April 2013.These findings suggest that the long-term seismicity near Iriomote Island is strongly affected by changes in the crustal strain rate, which have occurred in the past in response to dike intrusions in the Okinawa Trough and slow earthquakes in the Ryukyu Trench.
