Afterslip distribution of 2017 Iran M_W7.3 earthquake and its triggering effects on the 2018 M_W6.0 earthquake

In this study, a set of radar images acquired by the Sentinel-1 satellite that covers the interested seismically-effected area were collected. The time-series surface deformation of the 283-day time span after the 2017 Sarpol Zahab, Iran, M_W7.3 earthquake was extracted by using small baseline subset technique, then the two-step procedure inversion is carried out to obtain the afterslip distribution. In order to analyze the triggering effects of the 2017 strong earthquake and its post-seismic faulting on the 2018 Javanrud M_W6.0 earthquake, the coseismic deformation field covering the whole M_W6.0 earthquake region was obtained by using differential interferometry technique, and the inversion results of seismogenic fault parameters were used as receiving fault parameters for stress calculation. The results show that the post-seismic deformation of the Sarpol Zahab earthquake is mainly dominated by the afterslip effect. 283 days after the earthquake, the accumulative slip of the after-slip model reaches up to 0.7 m. The coseismic source model of the Javanrud M_W6.0 earthquake indicates that the seismogenic fault strike is 355.6°, the dip angle is 89.4°, and the rupture of coseismic fault is characterized by the right-lateral strike-slip together with some normal dip-slip component. Moreover, the calculated Coulomb stress change suggests that the M_W7.3 earthquake and its afterslip have triggering effect on the subsequent Javanrud M_W6.0 earthquake, and the occurrence of Javanrud earthquake could also be contributed by the regional plate activity.