Fig. 4.

Comparison of the MT responses in TM mode among the three numerical solutions and the analytical solution for the period of 32 s. The top and bottom panels show the apparent resistivity and phase, respectively. In each panel, the red line (ana) is the analytical solution, the green broken line (R0) is the calculated result using the rectangular grid shown in Fig. 3(b). T0 and T1 indicate the calculated results by the original Utada’s (1987) forward code and the new 2-D FEM code developed in this study. T0 and T1 used the triangular grid shown in Fig. 3(a).