Using a known solution for the electric potential and Ampère’s law, the azimuthal component of the magnetic field is deduced in a horizontally layered medium with a current point source placed anywhere, considering that the resistivity in each layer varies exponentially with depth. This theoretical result contributes to model the magnetometric resistivity method, which had been applied onshore, e.g., for mineral exploration, offshore to investigate the permafrost layer at bottom sea, hydrothermal flux, and natural resources. We have numerically tested the obtained formulation against previous results found in the literature that use distinct electrode and sensor dispositions, with models having three and four layers. Introducing the exponential variation, it verified the sensitivity to physical and geometric parameters comparing the exponential and homogeneous models.

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