Assessment of surface deformation patterns using InSAR data: Implications for human impacts in Makkah City, Saudi Arabia

Makkah City is undergoing extensive urban development to accommodate the growing number of Hajj pilgrims. This study applied Persistent Scatterer Interferometric Synthetic Aperture Radar (PS-InSAR) to map ground surface deformation in Makkah using a time series of 166 Sentinel-1 radar images acquired between December 2017 and January 2021. PS-InSAR enables the measurement of tiny displacements over time using phase differences between SAR images. A total of 85,484 persistent scatterers were identified, and their line-of-sight deformation velocities were estimated. The results show that deformation rates in Makkah City ranged from −19.1 to +19.1 mm/year during the study period, with positive velocities indicating movement away from the radar (ground swelling) and negative velocities representing motion towards the radar (subsidence). Spatial patterns of deformation correlated well with ongoing construction projects such as tunneling, infrastructure development, and groundwater extraction. This study demonstrates the capability of PS-InSAR for detailed and high-precision monitoring of urban ground motions caused by human activities in highly sensitive regions like Makkah. Continuous deformation monitoring is important for ensuring the safety and preservation of cultural heritage in the holy city.