2017年伊朗M_(W)7.3地震的震后余滑分布及其对2018年MW6.0地震的触发影响

Afterslip distribution of 2017 Iran M_(W)7.3 earthquake and its triggering effects on the 2018 M_(W)6.0 earthquake

收集了覆盖监测区域的Sentinel-1卫星雷达影像,利用短基线集干涉测量技术提取了2017年伊朗萨波尔扎哈布M_(W)7.3地震后283天的地表时序形变,通过二步法反演得到其震后余滑分布,之后采用差分干涉技术获取了2018年发生于同一地区的贾万鲁德M_(W)6.0地震的同震形变场,并将反演所得的发震断层参数作为应力计算的接收断层参数,来分析2017年M_(W)7.3强震及其震后活动对2018年贾万鲁德M_(W)6.0地震的触发影响。结果表明:萨波尔扎哈布地震的震后形变主要由孕震断层面的余滑运动所致,震后283天余滑模型的累积滑移量达到0.7 m;2018年贾万鲁德地震的发震断层走向为355.6°,倾角为89.4°,同震断层破裂以右旋走滑为主,兼具部分正断层运动。本文所得的贾万鲁德地震断层平面上的库仑应力变化表明,2017年M_(W)7.3主震及其震后余滑对2018年M_(W)6.0地震的发生具有一定的触发效应,M_(W)6.0地震的发生可能与区域板块的活动性相关。

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_(W)7.3 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_(W)6.0 earthquake,the coseis-mic deformation field covering the whole M_(W)6.0 earthquake region was obtained by using dif-ferential 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_(W)6.0 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_(W)7.3 earthquake and its afterslip have trig-gering effect on the subsequent Javanrud M_(W)6.0 earthquake,and the occurrence of Javanrud earthquake could also be contributed by the regional plate activity.