InSAR Postseismic Displacements of the 2023 Turkey Earthquakes

The two major earthquakes (magnitude 7.8 and 7.6) in southeastern Turkey in 2023 resulted in a combined fault rupture length of 500 km. The events were driven by the northward motion of the Arabian Plate colliding with the Eurasian Plate and the westward escape of the Anatolian Plate. The coseismic deformation field revealed a predominantly left-lateral strike-slip motion in both earthquakes. In addition to coseismic studies, research into postseismic relaxation processes provides critical insights into fault properties, as well as the deep structure of the lower crust and upper mantle, offering valuable support for understanding the regional tectonics and fault dynamics.

We use Interferometric Synthetic Aperture Radar (InSAR) and Sentinel-1 data to analyze the surface deformation over a 20-month postseismic period following the earthquakes. To comprehensively cover the affected area, we collected data from three ascending and three descending Sentinel-1 tracks, each comprising 4-5 consecutive frames. In total, we processed SAR data from 28 frames with approximately 50 temporal samples. Using the SIGMA approach developed by our team, we derived time-series displacement results. We further integrated GNSS data with the DetrendInSAR method, enabling the correction of atmospheric delays and the unification of displacement reference across multiple tracks. Neglecting the north-south component in the InSAR line-of-sight observations, we decomposed the ascending and descending data to derive the east-west and quasi-vertical displacement time series. The results reveal that the east-west displacement field displays both shallow near-fault afterslip signals and large-scale deformation signals far from the fault, indicating that the postseismic process involves not only shallow afterslip but also deep viscoelastic relaxation. The vertical displacement results show significant subsidence and uplift, consistent with surface deformation characteristics caused by deep viscoelastic relaxation. 

By processing postseismic SAR data from the 2023 Turkey earthquakes, this study elucidates the characteristics of surface deformation in the aftermath of the events. Through postseismic modeling, it further uncovers key parameters of the subsurface structure and fault slip behavior in the study area, contributing significantly to our understanding of the dynamics of the Anatolian Plate.