Slingram Frequency-domain EMI - 3D Linear Inversion of Magnetic Susceptibility Measurements

The very limited range of magnetic permeability variations (from 1.0001 to 1.01 in relative values) that can be observed in soils allows performing 3D linear inversions. To achieve this goal, we propose to successively define a reference conductivity and susceptibility profile, apply a 2D (x, y) Fourier transform to the apparent susceptibility variations mapped by the different instrument geometries, invert in z in the spectral domain over a series of predefined layers and determine the lateral variations in each layer by inverse Fourier transform. This process is applied to both synthetic and archaeological survey data.