Geophysical Characterization of Subsurface Suitability for Infrastructure at Ayat Real Estate Foundation, Addis Ababa

Abstract

<title>Abstract</title> This study provides a detailed geophysical assessment of subsurface conditions at the Ayat Real Estate site in northeastern Addis Ababa, employing electrical resistivity tomography (ERT), vertical electrical sounding (VES), and seismic refraction methods. Data from four VES points, dipole‒dipole ERT lines, and seismic refraction profiles reveal nearly vertical fractures and weak zones oriented NW–SE, which could impact foundation design, with competent hard formations suitable for construction located at depths of up to 12 m. The findings show increasing resistivity and P-wave velocity with depth, indicating progressively stronger subsurface materials, whereas low resistivity at shallow depths highlights physically weak zones. The subsurface consists of four layers: highly plastic clay with low resistivity (3.03–25 Ω-m) and P-wave velocities (&lt; 0.42 km/s); a middle layer with moderate resistivity (30–42 Ω-m) and P-wave velocities (&lt; 1.79 km/s); higher resistivity bedrock (38–65 Ω-m) with P-wave velocities (&lt; 2.4 km/s); and a deeper, slightly weathered bedrock layer with resistivities of 86–206 Ω-m. Structural features and fractures indicate potential saturation or weathering. These findings highlight the need for drainage, compaction, and stabilization to manage soil expansion and geohazards. Geophysical data combined with borehole information confirm the site's suitability for multistory construction and provide key insights for foundation design.