This geophysical investigation was commissioned to assess potential subsurface causes for structural failures observed at Coral Sands Luxury Apartments in Nyali, Mombasa. The investigation was prompted by the appearance of cracks in several structural columns and beams. Electrical Resistivity Tomography (ERT) and Multichannel Analysis of Surface Waves (MASW) were employed to map geoelectrical and mechanical variations in the subsurface.

Key findings indicate shallow zones of weak, saturated soils at various locations extending to depths of approximately 2 to 10 meters across the site, especially pronounced near the failing columns. The zone of structural failure corresponds spatially to both a low-resistivity anomaly (ERT) and a low shear-wave velocity zone (MASW), supporting the presence of mechanically compromised material and a suspected void or poorly compacted fill. Grouting activity underway during the survey coincides with this critical anomaly.

Recommendations included undertaking borehole drilling, Grouting and conducting a post grouting geophysical surveys as well as considering deep foundation systems for long-term structural stability. The integration of ERT and MASW data provided a high- confidence interpretation of subsurface conditions impacting structural performance.