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

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: In this study, we first use ESA Sentinel-1 data to obtain the co-seismic deformation of the 1 July and 30 November events by 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; and finally, we discuss the fault geometry of this earthquake sequence and its impact on infrastructure and highways in earthquake areas. Result: Results show that all events in this earthquake sequence were thrust-type, with the maximum coseismic deformation reaching 36 cm, which, together with the induced geohazards, caused 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 was 2.4 m, occurring at a depth of ~8 km, and the maximum slip on the fault of the 30 November earthquake was 0.48 m (~7 km deep). The Coulomb stress change results reveal that the 1 July earthquakes had 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.