Sentinel-1 InSAR observations and time-series analysis of co- and post-seismic deformation mechanisms of the 2021 Mw 5.8 Bandar Ganaveh Earthquake, Southern Iran

In the past two decades, because of the significant increase in the availability of differential interferometry from synthetic aperture radar and GPS data, spaceborne geodesy has been widely employed to determine the co-seismic displacement field of earthquakes. On April 18, 2021, a moderate earthquake (Mw 5.8) occurred east of Bandar Ganaveh, southern Iran, followed by intensive seismic activity and aftershocks of various magnitudes. We use two-pass D-InSAR and Small Baseline Inversion techniques via the LiCSBAS suite to study the co-seismic displacement and monitor the four-month post-seismic deformation of the Bandar Ganaveh earthquake, as well as constrain the fault geometry of the co-seismic faulting mechanism during the seismic sequence. Analyses show that the co- and post-seismic deformation are distributed in relatively shallow depths along with an NW-SE striking and NE dipping complex reverse/thrust fault branches of the Zagros Mountain Front Fault, complying with the main trend of the Zagros structures. The average cumulative displacements were obtained from -137.5 to +113.3 mm/yr in the SW and NE blocks of the Mountain Front Fault, respectively. The received maximum uplift amount is approximately consistent with the overall orogen-normal shortening component of the Arabian-Eurasian convergence in the Zagros region. No surface ruptures were associated with the seismic source; therefore, we propose a shallow blind thrust/reverse fault (depth similar to 10 km) connected to the deeper basal decollement fault within a complex tectonic zone, emphasizing the thin-skinned tectonics.