High resolution electromagnetic landscape mapping with multi-channel FDEM instruments

While frequency domain electromagnetic induction (FDEM) sensors are often used in soil and environmental studies, their application remains largely limited to coarse resolution surveys. Particularly in comparison to use of magnetometry or ground penetrating radar arrays that integrate multiple sensors in large setups to enable efficient large-area prospecting, the deployed survey speeds and spatial resolution obtained with FDEM lags behind. While impeding survey efficiency, this equally prevents reliably deploying more advanced processing procedures that require dense sampling grids such as 3D inversion or automated interpretation schemes.

This lagging implementation potential is a consequence of the type of commercially available instrumentation, generally consisting of a transmitter, generating an oscillating magnetic field, and one or more receivers that record the subsurface response to the emitted field. Combining such instruments in array setups is prevented by their uniform operating frequency, which is required for obtaining uniform measurements across the array but limited by interferences between instruments operating at similar frequencies.

In this project, we will develop a mobile, multi-channel FDEM array consisting of at least three novel multi-receiver FDEM instruments that operate at small offsets from a central operating frequency. This enables recording quasi-similar subsurface responses without cross-channel interference. Alongside instrumental development, adaptive processing software will be composed to enable robust calibration and processing of collected array data. While first project stages comprise constructing and testing a practical field setup and software development, a second phase will consist of large-area FDEM prospection and integration of (semi-)automated interpretation schemes.