Evaluation of near-surface deposit stiffness and site characterization through seismic refraction tomography in diriyah urban development area, Saudi Arabia

Rapid urban development in Diriyah, Saudi Arabia, necessitates detailed subsurface investigations to ensure structural safety and sustainable land use. This study employs seismic refraction and refraction tomography to characterize near-surface geotechnical properties across nine sites within the city’s northwestern expansion zone. The results reveal three distinct subsurface layers ranging from stiff alluvial deposits to massive limestone bedrock with increasing seismic velocities and material stiffness at greater depths. Geotechnical parameters such as shear modulus, bulk modulus, and bearing capacity indicate that the central region offers the most stable ground conditions, making it highly suitable for construction. According to NEHRP site classifications, the area comprises dense soils and competent rock (Classes C and B), further validating its suitability for construction. The integrated use of seismic methods offers a robust framework for site characterization, supporting resilient urban infrastructure and contributing to the broader goals of sustainable urban development in geologically variable environments.