Identification of a Potential Geothermal Resource at Aguas de Vichy Hot Springs, Colombia, Through Integrating Geoelectrical and Electromagnetic methods

Juan Camilo Mejía-Fragoso , José David Sanabria-Gómez, Rocio Bernal-Olaya

The Aguas de Vichy thermal spring, identified by the Colombian Geological Service (SGC) and located in Santander, Colombia, represents a significant but underexplored geothermal resource. This study presents the first geophysical imaging of the system, integrating Electrical Resistivity Tomography (ERT), Induced Polarization (IP), and Time-Domain Electromagnetics (TDEM) to characterize its structure. Existing geochemical analyses reveal high salinity and elevated temperatures, indicative of energy potential and an advection-dominated thermal regime. The geological context is marked by north–south and northeast–southwest fault systems intersecting Cretaceous and Precambrian rocks, overlain by a Quaternary aquifer.

Four ERT profiles and two TDEM soundings were acquired to characterize the geothermal system at Aguas de Vichy. ERT 1 and 2, crossing the main fault, revealed strong lateral resistivity contrasts (near 0 to > 1500 Ω·m) associated with clays, groundwater, and thermal anomalies, while the third ERT, located away from the fault, showed a predominantly resistive background suggesting limited geothermal influence. Complementary TDEM soundings extended the investigation to ~100m depth, identifying a low-resistivity anomaly interpreted as a geothermal reservoir and suggesting a fault-aligned hot-water plume feeding the aquifer.

These findings support a convective flow driven by vertical fluid ascent along the fault zone in addition to the previous advection-based hypothesis. The integrated geophysical dataset highlights the complexity and geothermal potential of the system, providing critical insights for future exploration and contributing to Colombia’s energy transition roadmap.