Subsurface leak detection and landslide risk assessment using ERT and 3D imaging in Northeastern Brazil

Landslides induced by subsurface water infiltration represent a growing hazard in rapidly urbanizing regions, particularly where infrastructure is deficient. Leakage from potable water distribution systems can trigger slope instabilities that often remain undetected by conventional rainfall-based early warning systems. This study employs electrical resistivity tomography and three-dimensional resistivity imaging to identify leakage pathways and assess subsurface moisture conditions in a high-risk sector of Recife municipality, Northeastern Brazil. High-resolution 2D and 3D multigrad array surveys were conducted and converted into volumetric soil moisture estimates using empirical relationships. The results reveal a major infiltration zone and several shallow, spatially distributed leaks, with saturation levels frequently exceeding 30–40%, particularly in low-resistance soil layers as corroborated by standard penetration test data. Three-dimensional isosurface visualizations of moisture distribution further delineate critical saturation volumes. These findings highlight the utility of resistivity-based geophysical methods for detecting non-meteorological landslide triggers and support their integration into proactive risk monitoring strategies in vulnerable urban environments.