A quantitative geophysical–geotechnical framework for slope stability analysis using electrical resistivity tomography

Abstract Slope instability constitutes a major constraint on infrastructure development in geologically complex and rapidly urbanizing regions such as West Java, Indonesia. Reliable slope stability analysis requires spatial characterization of subsurface mechanical parameters, including cohesion, internal friction angle, and bulk density. Conventional geotechnical investigations provide accurate point-scale data but are often constrained by high cost, limited spatial coverage, and logistical challenges. This study presents an integrated geoelectrical–geotechnical framework enabling the quantitative use of electrical resistivity for slope stability assessment. The investigation was conducted in the Padalarang District, West Bandung Regency, an area dominated by volcanic lithologies. Electrical Resistivity Tomography and Vertical Electrical Sounding were integrated with borehole logs, Standard Penetration Test data, and laboratory measurements to derive empirical correlations between resistivity and key geotechnical parameters. The results indicate a very strong correlation between electrical resistivity (ρ) and cohesion (R 2 = 0.8270), a strong correlation with bulk density (ρᵦ) (R 2 = 0.6860), and a weak correlation with internal friction angle (R 2 = 0.1780). The resistivity-derived parameters were incorporated into limit-equilibrium slope stability analysis under the specified groundwater condition. The representative resistivity-derived parameter model produced a Factor of Safety (FoS) of 2.60, while the final spatially integrated slope model yielded a minimum FoS of 1.23. These results demonstrate that electrical resistivity can provide spatially continuous, site-specific geotechnical information for preliminary slope stability assessment when calibrated and constrained by borehole and laboratory data.