Delineation of fracture zones in the part of Vindhyan fringe belt of Ahraura region, Mirzapur district, Uttar Pradesh, India using integrated very low frequency electromagnetic and resistivity data for groundwater exploration

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Integrated electrical and electromagnetic geophysical methods were used to delineate fracture zones in the part of Vindhyan fringe belt of Ahraura region of Mirzapur district, Uttar Pradesh, India for groundwater exploration. Groundwater occurs in fractures in hard rock area. A detailed survey of the area was done using satellite imagery to extract the lineament, and appropriate locations were selected for integrated electrical (resistivity method) and electromagnetic (VLF-EM) geophysical surveys. Very low frequency electromagnetic (VLF-EM) survey was conducted along ten traverse profiles. Qualitative interpretation of VLF-EM was done using Fraser and Karous-Hjelt filtering techniques which generate Fraser-filtered real data curves as well as pseudo-current density cross section along each profile. The interpretation result (anomaly) of VLF-EM may or may not delineate the appropriate fracture zone based on a number of higher values of relative current density which correspond to the subsurface feature. Four gradient profiling (GP) surveys of DC resistivity method were carried out at the position of the VLF-EM anomaly and to correlate the anomaly of gradient profile and VLF-EM anomaly which located the position of vertical electrical sounding (VES) and also the fracture zone. VLF-EM and subsequent resistivity surveys (GP and VES) at suitable locations suggest the existence of a fracture zone in the part of Vindhyan fringe belt of Ahraura region of Mirzapur district for the purpose of groundwater exploration.