<![CDATA[Liku Sembilan, Central Bengkulu, is a landslide-prone area characterised by steep topography, intense weathering, and high annual rainfall. This study aims to identify the geometry and depth of the slip surface using integrated 2D and 3D Electrical Resistivity Imaging (ERI) to improve the characterisation of subsurface conditions associated with landslide occurrence. Data acquisition was conducted using the Wenner–Schlumberger array with 48 electrodes. The 2D survey was performed along a 94 m profile with 2 m electrode spacing, while the 3D survey covered approximately 1,750 m² using six parallel lines with 5 m line spacing and 10 m electrode spacing. Data were processed using Res2DInv and ERTLab-ViewLab3D. The inversion model produced an RMS error of 34.3% at the second iteration, which is considered acceptable given the complex topographic and geological conditions of the study area. The results reveal a low-resistivity zone (18–53 Ω·m) at a depth of approximately 5–10 m, interpreted as a water-saturated clay layer that serves as the main slip surface. The identified slip surface exhibits a curved geometry with a slope of 25–35°, indicating a rotational landslide mechanism. The integrated 2D and 3D ERI models provide a more comprehensive visualisation of the spatial continuity and geometry of the slip surface than a single-model approach. In addition, very low-resistivity zones (1–10 Ω · m) indicate areas of groundwater accumulation that may contribute to slope instability. These findings demonstrate the effectiveness of combined 2D and 3D ERI for landslide characterisation in tropical volcanic terrains and provide important information for slope-hazard mitigation and subsurface drainage planning.]]>
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