Magnetic exploration for geothermal power: a case study of Tattapani thermal spring

Abstract

Rapid industrialization and population growth have placed increasing pressure on conventional energy resources, prompting the need for reliable, low-emission alternatives. Geothermal energy, with its capacity for both thermal and electrical production, remains largely untapped in Pakistan despite abundant thermal springs and favorable tectonic settings. In this study, we evaluate the potential of the Tattapani thermal spring, located within the Hazara-Kashmir syntaxis of the Sub-Himalayan fold-thrust belt, using an integrated ground magnetic approach. A grid of 1,107 measurements spaced at 50 × 50 m was collected with a proton precession magnetometer. Hierarchical statistical analysis of total magnetic intensity and residual magnetic data delineated five distinct magnetic zones, ranging from low-intensity magnetic thermal zone to high-intensity backgrounds each corresponding to different lithologies confirmed by X-ray diffraction. The Tattapani thermal spring exhibits a total magnetic anomaly of about 500nT, which more clearly emphasizes local variations than absolute IGRF-dependent field values. First-order derivative filters (dx, dy, dz) and downward continuation to 1,000 m sharpened fault-controlled alterations, while Euler deconvolution (structural index 0–1) revealed that over 70% of causative bodies lie within 60 m of the surface, with nearly half concentrated in the MTZ. These shallow magnetic lows coincide with hydrothermal alteration halos developed along NE–SW fault intersections and an anticlinal contact between shale/marl and dolomite units. A conceptual model illustrates continuous recharge from the adjacent Poonch River through fault-bounded conduits, feeding the spring’s stable thermal output. Our findings show that Tattapani geothermal manifestation is structurally controlled by near-surface faults and is readily accessible, making it a strong candidate for sustainable power generation. To advance resource development, we recommend targeted gravity surveys to resolve deeper structures, exploratory drilling up to 01 km for direct temperature and permeability measurement, comprehensive geochemical and geotechnical testing, environmental impact assessment, within a phased exploration framework. This study shows that by integrating magnetic data with prior resistivity results can augment existing methods to refine subsurface interpretations and advance geothermal exploration in the region.