AEMINV is a computer program for geophysical interpretation of frequency-domain airborne electromagnetic (AEM) data using one-dimensional (1-D) layered earth model. Multiple profiles, i.e., measurement lines can be processed simultaneously. The model parameters are the electrical resistivity and thickness of the layers and the resistivity and magnetic susceptibility of the basement layer. Depending on the number of frequencies (max 10) 1-3 layer models can be utilized. The inversion can also optimize the resistivity of the half space and the depth to the basement, which is equal to the traditional apparent resistivity (conductivity) and depth transformation.
Two source-receiver systems, a) vertical loops = horizontal magnetic dipoles (HMD) or b) horizontal loops = vertical magnetic dipoles (VMD), and two measurement configurations, a) in-line (along flight line) and b) broadside perpendicular to the flight line) are considered. Although AEMINV was originally developed for airborne applications, it can also be used to interpret ground EM data (eg., Apex Maxmin II).
The inversion is made independently for each data location using one-dimensional layered earth model. Laterally constrained inversion is achieved by minimizing the roughness of the model, i.e. the variation of the model parameters between neighboring points together with the data error. As the result of the constrained (Occam) inversion a smoothly varying model is obtained. The roughness and/or the fix/free status the parameters can be set manually to allow discontinuities and to incorporate a priori data in the model. Note that the model is one-dimensional and that the pseudo-section resulting from the inversion does not represent true 2-D resistivity distribution.