Modelling accuracy limits for frequency-dependent anisotropy of magnetic susceptibility of rocks and soils

The frequency-dependent anisotropy of magnetic susceptibility (AMS) can be most easily determined through subtracting directional susceptibilities measured at two operating frequencies along each of the measuring directions and the differences subsequently processed using standard methods for AMS computation. The effect of the measurement precision on the accuracy of the determination of the frequency-dependent AMS is investigated through mathematical simulation of the measurement process using the statistical theory of measuring the AMS of rocks. The accuracy of the AMS determination is presented in terms of the errors in determining the principal susceptibilities and principal directions. By modelling the measuring errors, the limits are discovered for the investigation of the frequency-dependent AMS. The modelling shows extremely high requirements for measurement accuracy met by the most sensitive instruments, only.