Integrated <scp>VES</scp> – <scp>ERI</scp> – <scp>MASW</scp> ‐Geotechnical Investigation for Building Foundation Site Suitability at the Proposed Wachemo University Referral Hospital, Hosanna, Central Ethiopia

ABSTRACT This study integrates Electrical Resistivity Imaging (ERI), Vertical Electrical Sounding, Multichannel Analysis of Surface Waves (MASW), and standard penetration test (SPT) to evaluate subsurface stratigraphy and foundation bearing capacity at a proposed construction site in Hosanna, Central Ethiopia. The investigation aims to characterize soil stiffness variability and assess suitability for structural foundations in a terrain dominated by heterogeneous residual soils over volcanic formations. ERI results further delineate low‐resistivity clay‐rich zones (&lt; 20 Ω·m) with low bearing capacity, intermediate silty layers (20–100 Ω·m), and high‐resistivity competent SP and volcanic units (&gt; 120 Ω·m) with improved foundation performance. MASW results indicate V s values ranging from 160 m/s to 275 m/s, corresponding to allowable bearing capacities between 91 kPa and 165 kPa. A linear relationship between q all and V s is obtained ( q all = 0.5933 V s , R 2 = 0.8085), confirming a strong dependence of bearing capacity on soil stiffness. SPT data were used to estimate allowable bearing capacity ( q all ) at foundation depths of 3.0 m, 5.5 m, and 8.0 m, while MASW‐derived shear‐wave velocity ( V s ) and ERI resistivity data were used for independent geotechnical validation. The soils are classified as MH, ML, and SP under the Unified Soil Classification System (USCS). SPT results show a strong linear correlation between q all and corrected SPT N ‐values or (N1)60 expressed as q all = 17.289 (N1)60 with R 2 = 0.9564, indicating that SPT explains approximately 95.6% of bearing capacity variability. The estimated q all ranges from 133 kPa to 510 kPa, increasing with depth and soil density. Weak MH/ML soils dominate shallow depths, while more competent SP and weathered volcanic units occur at greater depths. Overall, the site exhibits moderate to good foundation conditions, with recommended construction zones where V s exceeds 200 m/s and q all is greater than 150–200 kPa, while weak low resistivity zones should be avoided or improved prior to development.