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Subsidence of ground is a common global problem. Several environmental and ecological destructions can observe due to subsidence. The present geophysical study includes investigating the subsidence of railway tracks in Salanpur, Paschim Bardhaman district, West Bengal (India). Electrical Resistivity Tomography (E.R.T.), an advanced geophysical method, has been applied to locate and delineate subsurface cavities mainly responsible for subsidence. ABEM-Terrameter LS-2 instrument incorporated for data acquisition with the prospecting techniques of Wenner, Wenner-Schlumberger, Dipole-dipole, and Gradient array. The generated forward model using the Res2dmod algorithm includes hollow and filled cavities to simulate the subsurface response. 2D inversion and sensitivity analysis was carried out through the Res2dinv program based on a smoothness constrained regularized least-square optimization procedure for different electrode configurations. E.R.T. survey has shown its proficiency in detecting various cavities and unstable subsurface zone responsible for railway track subsidence. The present research paper could help to locate subsidence-prone zones in different areas.

<p>Subsurface cavities are mainly responsible for ground subsidence in and around coal mines. There is need to use an advanced high-resolution three-dimensional (3D) Electrical Resistivity Tomography (ERT) technique to detect anomalies and map subsurface precisely. The present study demonstrated the numerical evaluation of 2D and 3D-ERT for air-filled and water-filled cavities. Models simulated with reasonable resistivity values for voids and formations by considering bord and pillar mining environments in multilayer earth. Wenner, Wenner-Schlumberger, and Dipole-dipole arrays incorporated with and without a barrier to getting the best possible output. We used the Res2dinv and Res3dinv programs for data processing. 3D Dipole-dipole inverted geo-electrical section better showed the subsurface cavities signature than the results obtained from other applied arrays. The sensitivity section corresponding to used electrode configurations gives a more detailed picture of the subsurface for better interpretation. The 3D volume of the subsurface overcomes the limitations of 2D ERT to detect cavities within the coal seam.</p>