Fig. 1. Two-dimensional model consisting of resistive (5000 Ω m) and conductive (2 Ω m) vertical blocks embedded in a 100 Ω m homogeneous media.

Fig. 2. Apparent resistivity and phase pseudo-sections calculated from the conventional TE–TM and new series–parallel impedances. (a) TE mode; (b) parallel impedance; (c) TM mode; (d) series impedance.

Fig. 3. Three-dimensional model consisting of two vertical plates placed perpendicularly to each other at a depth of 1.0 km within a 100 Ω m homogeneous media. The dimensions of the plates are indicated in the images projected at the coordinate planes.

Fig. 4. Plan views of apparent resistivity on top of the 3D model of Fig. 3, for the case when both plates are conductive (2 Ω m). The four images represent anomalies for a period of 10 s, as derived from the xy and yx conventional impedances and from the series and parallel impedances. (a) XY; (b) YX; (c) series; (d) parallel.

Fig. 5. Phase response calculated from the same set of impedances used in Fig. 4. (a) XY; (b) YX; (c) series; (d) parallel.

Fig. 6. Plan views of apparent resistivity on top of the 3D model of Fig. 3, for the case when the plate oriented along x direction is resistive (5000 Ω m), and that oriented along y direction is conductive (2 Ω m). The four images represent anomalies for a period of 10 s, as derived from the xy and yx conventional impedances and from the series and parallel impedances.

Fig. 7. The 3D model consisting of two parallel blocks 1.2 km deep in a 100 Ω m homogeneous media. The resistive block is 5000 Ω m and the conductive one is 2 Ω m. The dimensions of the blocks are indicated in the images projected at the coordinate planes; 2D inversion of S–P data was performed along profiles A, B and D.

Fig. 8. Resistivity models recovered by the 2D inversion of: (a) line A, (b) line B and (c) line D. Misfit at every site is indicated at the top of each model. Outlines of the target blocks are indicated with dashed line.

Fig. 9. Resistivity models resulting from the 2D inversion of the S–P impedances computed from the COPROD2 data set. (a) S–P data computed from TE and TM provided impedances. (b) S–P data computed from the full impedance tensor. NACP and TOBE anomalies are well recovered in both S–P data sets. Both resulting models are also comparable with those discussed by Jones (1993).