Geothermal Energy Exploration Using Magnetic Anomaly Data

Geothermal energy exploration using magnetic anomaly data exploits variations in the Earth’s magnetic field to infer subsurface thermal and structural properties. Magnetic anomalies arise from contrasts in rock magnetisation, which in turn reflect temperature‐dependent magnetic mineralogy. By analysing spatial and spectral characteristics of these anomalies, geophysicists estimate Curie-point depths (the depth at which rocks lose permanent magnetism), map lithospheric magnetic thickness and derive heat-flow distributions. Aeromagnetic surveys, satellite magnetometry and global compilations of magnetic data provide the raw observations, which are interpreted through inversion algorithms and power-spectrum techniques. Integration of magnetic‐based thermal models with geological, geochemical and remote-sensing data enables identification of high-potential geothermal targets, reduces drilling risk and informs regional energy planning. Advances in computational methods and data resolution now allow both continental-scale assessments and detailed site investigations, offering a cost-effective and rapid approach to underpin the expansion of low-emission, base-load renewable energy worldwide.

Research from Nature Portfolio

Efforts have delivered the first global reference model of Curie-point depths derived from a fractal magnetisation inversion of magnetic anomaly data. This foundational work reveals that continental Curie depths are often bimodal—shallow in old cratons and deeper in tectonically active margins—while oceanic depths are strongly influenced by hydrothermal circulation and spreading rates. Correlative analyses between Curie-point depths and measured heat-flow values verify theoretical conductivity models and yield a global average heat-flow estimate of approximately 70 mW m⁻². The inversion methodology demonstrates robustness across diverse tectonic regimes, providing a universal framework for preliminary geothermal potential assessment and guiding both global surveys and regional exploration programmes.

Research from all publishers

On a continental scale, aeromagnetic-derived heat-flow estimates have been incorporated into a geographic information system to generate the first geothermal-favourability map of Africa. By integrating Curie-depth inversion results with geological formations, fault density, volcanic activity and hydrothermal manifestations, researchers identified fourteen high-potential regions, streamlining target selection and reducing exploration costs. At a more local scale, spectral analysis of aeromagnetic anomalies in a southwestern Nigerian warm spring area produced Curie-point depths around 15 km, correlating with independent heat-production estimates and confirming the presence of shallow magmatic intrusions beneath thermal springs. In northwestern South America, centroid and fractal spectral methods applied to aeromagnetic grids yielded Curie-point depths between 13 km and 47 km, from which geothermal gradients were calculated and mapped. These gradients show strong agreement with borehole temperatures and seismic bottom-simulating reflector data, resulting in updated heat-flow charts that support resource evaluation in both onshore and offshore settings.

Geothermal Energy Exploration Using Magnetic Anomaly Data publication trend

The graph below shows the total number of articles in geothermal energy exploration using magnetic anomaly data across all publications each year (not limited to Nature Index journals).

Technical terms

Aeromagnetic survey: Airborne measurement of the Earth’s magnetic field used to map variations caused by subsurface rock magnetisation.

Magnetic anomaly: A deviation in the observed magnetic field relative to a reference model, indicating contrasts in the distribution of magnetic minerals.

Curie-point depth: The depth at which crustal rocks reach the Curie temperature and lose stable ferromagnetism, used as a proxy for subsurface thermal structure.

Spectral analysis: A method that examines the frequency content of magnetic anomaly data to infer source depths and statistical properties of the magnetised layer.

Inversion algorithm: A computational procedure that translates magnetic observations into estimates of subsurface properties such as magnetisation, depth and thermal parameters.

Heat flow: The rate of thermal energy transfer per unit area from the Earth’s interior to the surface, commonly expressed in milliwatts per square metre (mW m⁻²).

References

1. A global reference model of Curie-point depths based on EMAG2. Scientific Reports (2017).
2. Geothermal renewable energy prospects of the African continent using GIS. Geothermal Energy (2022).
3. Spectral analysis of aeromagnetic data for geothermal energy investigation of Ikogosi Warm Spring - Ekiti State, southwestern Nigeria. Geothermal Energy (2014).
4. Curie point depth, thermal gradient, and heat flow in the Colombian Caribbean (northwestern South America). Geothermal Energy (2019).