Structural Controls on Geothermal Manifestations Using Integrated Geophysical Methods: A Case Study of the Tulu Moye Area, Central Main Ethiopian Rift

This study investigates subsurface geological structures and their influence on geothermal manifestations in the Tulu Moye geothermal field, located in the Central Main Ethiopian Rift. The study area lies between UTM coordinates 512000–514500 mE and 902000–904000 mN, at an elevation of approximately 2090 m above sea level. Integrated geophysical methods, including electrical resistivity and magnetic surveys, were employed to delineate subsurface structures associated with geothermal activity. A total of five Vertical Electrical Sounding (VES) points and three Electrical Resistivity Tomography (ERT) profiles were acquired using a SYSCAL PRO system, while 206 magnetic data points were collected along eleven profiles using a proton precession magnetometer. The resistivity data were processed using IPI2Win, RES2DINV, and Surfer software, whereas magnetic data were analyzed using Oasis Montaj. The results reveal that zones of low resistivity and low magnetic anomalies correspond to areas of potential geothermal fluid accumulation and hydrothermal alteration. The ERT models indicate a laterally continuous low-resistivity zone extending between 480 m and 640 m, interpreted as a fractured and altered zone facilitating fluid flow. Upward continuation of magnetic data highlights deeper structures, with low magnetic anomalies observed in the northeastern, southeastern, and central parts of the study area. Structural analysis using Euler deconvolution and analytical signal techniques indicates that the dominant subsurface lineaments trend in the northwest–southeast direction, acting as conduits for geothermal fluids. Overall, the integration of resistivity and magnetic methods effectively delineates geothermal potential zones and improves understanding of structural controls on geothermal systems in the Tulu Moye area.