Audio-magnetotelluric (AMT) studies over Rajapur hot spring in west coast Maharashtra, India

In the west coast geothermal provinces, the Rajapur hot spring, located in the southern part of western Maharashtra, is well thought to originate from the interaction of meteoric water with the granitic basement. A 3D AMT survey was conducted to determine the geo-electrical structure of the hot spring. Dimensionality analysis carried out by phase tensor analysis reveals complex subsurface 3D structures. 2D and 3D modelling have yielded three distinct resistivity layers in the Rajapur geothermal field. These layers include a moderately resistive surface layer representing weathered Deccan traps having a thickness of about 100 m, a conductive second layer with a thickness of about 100–400 m represents Kaladgi sediments and a deeper high resistive layer (0.5–1.0 km) representing granitic gneisses basement. High conductivity anomaly within the Kaladgi sediments represents a hydrothermal reservoir that is associated with faults/fractures beneath the Deccan Traps.