2.5‐D CSAMT Modeling with Finite Element Method Over 2‐D Complex Earth Media

This paper will discuss the characteristics of EM field for 2‐D complex earth media. Firstly we introduce the characteristics of electric field, magnetic field, apparent resistivity, and phase induced by a finite electrical dipole source over 100m homogeneous half‐space media. From this result we can know the field change behavior with the distance from transmitter to receiver, and also the result tells us we should use proper transmitting‐receiving mode. In wave number domain, the EM field shows that the field of low wave number contributes much more than the one of high wave number. And then we demonstrate the CSAMT forward modeling of apparent resistivity, phase pseudosections and frequency curves for two anomaly bodies, two slanting anomaly bodies and down faulted anomaly. Numerical modeling results show directly the anomaly characteristics, this is very helpful for understanding field data and data inversion and interpretation.