Q-factor approximation of electromagnetic fields for high-frequency sounding in the 300 kHz to 30 MHz range over layered media

摘要

A new method for rapid approximation of the EM field components for a VMD source on or above a layered earth has opened new doors for efficient inversion of HFS data. The method, called the HFS Q-method, is nearly as accurate as direct numerical integration, and in most cases can replace the time-consuming interpretation studies previously reported in Stewart et al. (1994). Many other classes of M-layer near-surface models were run to compare each of the three methods used in this paper. In almost all cases, the HFS Q-method showed acceptable agreement with the more exact numerical integration method in the 300 kHz to 30 MHz frequency range. Because of the accuracy and speed of the HFS Q -method, the numerical integration method may not be needed to obtain a final least-squares fit to observed HFS data. Hopefully, the HFS Q -method will become the method of choice for rapid interpretation of HFS data. The Q -method could easily be installed on a notebook PC for use in the field.