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11.4 Visualizing the Geoelectric Structures
The magnetovariational and magnetotelluric tests may give a good indication of
dimensionality of geoelectric structures, their position and strike. We detail these
indications by visualizing the geoelectric structures. This can be done in sev-
eral ways - for instance: (1) plotting tipper vectors (induction arrows), (2) con-
structing impedance and tipper polar diagrams, (3) drawing the profiles, maps,
pseudo-sections and pseudo-topographies of magnetotelluric and magnetovaria-
tional response functions.
11.4.1 Plotting Tipper Vectors
We will start with tipper vectors. Recall that in the Wiese convention the real tippers
diverge from conductive structures and converge to resistive structures. In the 2D
model they are perpendicular to the structure strike. Considering tippers, we classify
structures by their conductivity and trace their geometry.
Let us return to the model from Fig. 2.3. This superimposition model contains
a
-shaped resistive inclusion in the upper layer and a 2D deep regional conduc-
tive prism in the intermediate layer. Figure 11.37 presents the Wiese-Parkinson
and Vozoff tippers, Re
W
and
V
, calculated for period
T
=
160 s. One can see that
arrows Re
W
and
V
converge to the middle of the
-shaped resistive inclusion, the
V
-arrows giving somewhat more distinct pattern than the Re
W
-arrows.
Next we consider two instructive experimental examples.
Figure 11.38 presents a map of the Kirghiz Tien Shan with real Wiese-Parkinson
tippers Re
W
plotted for
T
1600 s (Trapeznikov et al., 1997). Southern regions
of the Kirghiz Tien Shan exhibit small chaotically oriented induction arrows. But
=
Fig. 11.37
Real Wiese-Parkinson tippers Re
W
and Vozoff tippers
V
over a near-surface
-shaped
resistive inclusion in the superimposition model shown in Fig. 2.3
