Interplate rheological contrast revealed by asymmetric deformation after the 2023 Kahramanmaraş earthquakes

Postseismic surface deformation offers key insights into subsurface lithospheric rheology and earthquake fault behavior, yet geodetic data often fail to capture its full complexity. Here, we use satellite radar images to derive time series of three-dimensional surface displacements following the 2023 Kahramanmaraş (Türkiye) earthquakes. The results show strong spatial and temporal deformation asymmetry across the East Anatolian Fault with the stiffer Arabian lithosphere exhibiting slower deformation decay than the Anatolian side. The temporal asymmetry excludes elastic afterslip from being the main postseismic process and instead the postseismic response is dominated by asymmetric viscoelastic relaxation as well as poroelastic rebound. These findings underscore the importance of both temporal and three-dimensional spatial deformation data in advancing understanding of post-earthquake recovery processes and subsurface lithospheric structure.