Present-day kinematics and short-term crustal deformation based on GNSS observations in the Nile Delta Region, Egypt

Abstract The potential environmental, economic, and social repercussions of land subsidence in the Egyptian Nile Delta make it a critical geodynamic concern. As one of the oldest deltaic systems in the eastern Mediterranean Basin, the Nile Delta is particularly susceptible to ongoing tectonic processes. Factors such as relative sea-level rise, reduced sediment supply and prolonged hydrocarbon extraction contribute to progressive surface deformation, further increasing its vulnerability. This study investigates present-day crustal kinematics and short-term deformation across the Nile Delta using Global Navigation Satellite System (GNSS) measurements collected from 2013 to 2023. Time-series data from ten permanent GNSS sites were processed to estimate both regional and local velocity fields, providing a detailed assessment of the delta’s crustal motion. High-precision geodetic analysis was applied to quantify deformation parameters, including horizontal and vertical motions, principal strain components, dilatation, and maximum shear strain. The results indicate spatially variable crustal behavior across the delta, largely governed by its structural configuration. The northeastern sector exhibits relatively higher subsidence compared to the northwestern part, suggesting enhanced exposure to relative sea-level rise. Absolute velocities range from 17 to 23.8 mm/year. Horizontal motions vary between −0.76 and 2.25 mm/year in the northing direction and between −1.25 and −0.89 mm/year in the easting direction, while mean vertical displacement reaches approximately −8.25 mm/year. The derived strain field reflects moderate shear deformation, implying a low overall seismic hazard within the study area.