利用InSAR观测研究2022年伊朗地震序列触发机制及其对基础设施的影响

Triggering Mechanism and Impact on Infrastructure of the 2022 Iran Earthquake Sequence Revealed by InSAR Observations

  • 摘要: 2022-07-01伊朗南部的霍尔木兹甘省发生两次Mw 6.0和一次Mw 5.7地震,11-30在距这两次地震不足10 km的位置,又发生了Mw 5.7地震。利用欧洲空间局哨兵一号数据,通过合成孔径雷达干涉测量技术获取2022-07-01—2022-11-30地震序列的同震形变场,进而利用弹性半空间的位错模型反演得到地震序列的断层参数和滑动分布,并利用库仑应力研究了07-01地震对11-30地震的触发关系,讨论了这一地震序列的断层几何和对公路等震区基础设施的影响。结果表明,这一地震序列均为逆冲型地震,最大地表永久变形量超过36 cm,地震造成了震中区域公路和房屋等基础设施不同程度损毁。07-01地震的断层最大滑动量为2.4 m,发生在地下8 km左右;11-30地震的断层最大滑动量约为0.5 m,发生在地下8 km左右。对地震序列进行库仑应力分析显示,07-01地震对11-30地震有显著触发作用。这一地震序列中,不同地震的发震断层在空间上交叉重叠度较高,说明可能发生在同一个逆冲断层系统,而这一断层系统是通过此次地震序列新发现的隐伏断层,其未来的地震危险性值得持续关注。

     

    Abstract:
    Objective On July 1, 2022, Two Mw 6.0 and an Mw 5.7 earthquake events occurred in Hormuzgan Province of southern Iran, followed by an Mw 5.7 earthquake on 30 November at a location of less than 10 km.
    Methods We first use European Space Agency Sentinel-1 data to obtain the coseismic deformation of the 1 July and 30 November events by interferometric synthetic aperture radar(InSAR)technique and invert the InSAR result for fault parameters and slip distribution of the earthquake sequence. Then we investigate the triggering relationship of the 1 July earthquakes to the 30 November earthquake by using the Coulomb stress. Finally, we discuss the fault geometry of this earthquake sequence and its impact on infrastructure and highways in earthquake areas.
    Results Experimental results show that all events in this earthquake sequence are thrust-type, with the maximum coseismic deformation reaching 36 cm, which together with the induced geohazards, cause varying degrees of damage to infrastructure (e.g., roads and houses in the epicenter area). The maximum slip on the fault of the 1 July earthquakes is 2.4 m, occurring at a depth of about 8 km, and the maximum slip on the fault of the 30 November earthquake is 0.5 m (about 8 km deep). The Coulomb stress change results reveal that the 1 July earthquakes have a significant triggering effect on the 30 November earthquake.
    Conclusions The high spatial overlap of the different earthquakes faults in this earthquake sequence suggests that they may have occurred on the same thrust-fault system, which are hidden faults newly discovered through the sequence. The future seismic hazard of this fault system deserves continued attention.

     

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