The UNESCO Agenda 2030 emphasizes the preservation of cultural heritage sites, focusing on coastal heritage preservation, which still poses substantial difficulties. While earlier studies have addressed the overall consequences of natural hazards along the Alexandria coastline, there's a gap in how they specifically affect coastal heritage sites, e.g., the Qaitbay citadel (our case study). This work seeks to bridge this gap by assessing the critical hazards faced by the Qaitbay citadel, including crustal deformation due to tectonic events, earthquakes, and Sea Level Rise (SLR) resulting from climate change. To comprehensively assess these challenges, a stack of Sentinel-1 SAR datasets (2017-2021) was processed using the Persistent Scatterer InSAR (PS-InSAR) technique to conduct spatial and temporal deformation variations of the citadel's site and its buildings. GPS measurements of Alexandria's (e.g., ALX2) station were correlated with InSAR results within the same period. Furthermore, satellite altimetry data from 1993-2021 covering the citadel and surroundings were processed to highlight long-term SLR trends. The findings indicate (1) A subsidence rate of -1 ± 0.2 mm/yr, associated with the citadel's foundational structures and identified through the PS-InSAR analysis, was caused by load-bearing effects and sand migration beneath the citadel, (2) a vertical displacement of -1.3± 0.6 mm/yr obtained from ALX2-GPS station, consistent with the LOS velocity rate of PS-InSAR time series analysis at that specific location, (3) a SLR trend of +3.96 mm/yr, with notable peaks potentially related to episodes of Northern Ionian Gyre reversal, that could result in changes in water mass redistribution in the surrounding region.

The Mw 7.1 earthquake occurred in Wushi County on 22 January 2024, representing the largest earthquake in the southern Tianshan Orogen for more than a century. Together with two subsequent strong aftershocks, this sequence allows us to examine the geometry of the complex fault system and interactions of seismic and aseismic slip. Using InSAR observations, we resolved the coseismic and postseismic deformation to constrain the slip distributions associated with the earthquake sequence. The results show that the mainshock ruptured a northwest-dipping fault, with coseismic slip mainly concentrated at depths of 10–30 km and peaking at approximately 2.7 m near 16 km, releasing a geodetic moment of 4.9 × 10¹⁹ N·m (Mw 7.1). The 2024 Mw 5.7 aftershock ruptured a surface-reaching fault with a peak slip of approximately 1 m at approximately 2 km depth, whereas the 2025 Mw 5.8 aftershock ruptured a nearby blind fault at depths of 5–10 km. Afterslip during the first six months occurred predominantly on the mainshock fault, and was largely complementary to the large coseismic slip zone. The cumulative geodetic moment released by the ~six-month afterslip was estimated to be 5 × 10¹⁸ N·m, equivalent to approximately 10.2% of the mainshock moment. The Coulomb stress analysis shows that the mainshock produced positive stress changes of approximately 1.6 bar and approximately 2.6 bar at the hypocenters of the Mw 5.7 and Mw 5.8 aftershocks, respectively, bringing both faults closer to failure. In addition, positive stress changes induced by postseismic afterslip on the Mw 5.8 fault indicate that time-dependent stress redistribution further promoted its failure. These results reveal the spatial and temporal partitioning of seismic and aseismic slip within a multi-fault system and highlight the importance of integrating coseismic rupture, postseismic afterslip, and stress-transfer processes to better assess postseismic seismic hazard in continental thrust regions.