InSAR-Derived Source Characteristics of Iranian Blind Reverse-Fault Earthquakes and Their Implications for Seismic Hazard Evaluation

Abstract

Investigating fault characteristics is necessary for seismic hazard evaluation and can provide useful insights for municipalities to optimize their investments in safer buildings and more resilient infrastructure. The location and the geometry of the faults, especially their relationship with sedimentary layer thickness, and the amount of stress drop are critical components when evaluating strong ground motions caused by earthquakes. Interferometric Synthetic Aperture Radar (InSAR) is a powerful tool for accurately determining fault parameters of shallow inland earthquakes and investigating their characteristics in terms of seismic hazards. In this study, based on our earlier results from InSAR data inversions conducted on five Iranian shallow blind reverse-fault earthquakes, we particularly exploited the resolving power of InSAR to investigate fault characteristics and discussed their implications for seismic hazard evaluation in Iran. For all studied Iranian earthquakes, the InSAR-derived fault was deeper than the sedimentary layer. This may indicate that these earthquakes did not rupture the entire seismogenic layer, likely leaving a significant seismic potential. Moreover, the average stress drop of the Iranian earthquakes was relatively large (13.4 MPa), which might be related to their immature blind reverse faults, leading to a possibility of generating stronger short-period ground motions, which should receive greater consideration in future seismic hazard analyses. As InSAR data can be easily accessed, this study presents a cost-effective method to provide fault parameters that can be used for the evaluation of strong ground motions caused by earthquakes, even in countries where observation networks of strong ground motions are not well developed.