2017年伊朗MW7.3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 MW7.3 earthquake and its triggering effects on the 2018 MW6.0 earthquake

  • 摘要: 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MW7.3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MW6.0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MW7.3强震及其震后活动对2018年贾万鲁德MW6.0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MW7.3主震及其震后余滑对2018年MW6.0地震的发生具有一定的触发效应,MW6.0地震的发生可能与区域板块的活动性相关。

     

    Abstract: 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, MW7.3 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 MW6.0 earthquake, the coseismic deformation field covering the whole MW6.0 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 MW6.0 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 MW7.3 earthquake and its afterslip have triggering effect on the subsequent Javanrud MW6.0 earthquake, and the occurrence of Javanrud earthquake could also be contributed by the regional plate activity.

     

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