High-Resolution Multichannel Analysis of Surface Waves (MASW) Imaging of Karst Features in Carbonate Environments of Eastern Saudi Arabia

Carbonate terrains of the Eastern Province of Saudi Arabia are highly susceptible to subsurface hazards due to intense weathering, fracturing, and karstification. Features such as dissolution cavities, weakened zones, and fault-related discontinuities pose significant risks to infrastructure in a region experiencing rapid urban and industrial development. Accurate and non-invasive characterization of these concealed features is therefore critical for geotechnical risk mitigation.

This study investigates the effectiveness of the Multichannel Analysis of Surface Waves (MASW) technique for identifying and characterizing karst features and fault zones in complex carbonate environments. MASW utilizes the dispersive behavior of Rayleigh waves to derive shear-wave velocity (Vs) profiles, which are sensitive to variations in material stiffness, fracturing, and void development. These velocity contrasts provide valuable indicators of subsurface heterogeneity associated with karst and structural deformation.

Field investigations were conducted at representative sites exhibiting varying degrees of carbonate weathering and karst development. Prior to full-scale data acquisition, parameter sensitivity analysis is performed to optimize survey design, including geophone spacing, spread length, source offset, and sampling interval. MASW data were processed through dispersion analysis and inversion to generate detailed Vs profiles and lateral velocity variations. Anomalous low-velocity zones and abrupt velocity gradients are interpreted as indicators of cavities, fractured layers, and fault zones. The results demonstrated that MASW provides reliable, high-resolution subsurface characterization in karst-prone carbonate terrains, offering a cost-effective and non-invasive tool for identifying geotechnical hazard zones and supporting safer infrastructure planning.