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In-Depth Information
1
S
Z
⊥
(0)
d
<<
v
≈
weak
screening
(7
.
91)
1
S
Z
⊥
(
y
)
d
>>
v
≈
strong
screening
.
The screening effect is exemplified in Fig. 7.28. Here the apparent-resistivity
curves obtained over the middle of the central conductive segment (
y
=
0) are
shown. They have been computed by the finite-element method (Wannamaker
et al., 1987). The resistivity
2
of the shielding layer takes the value from 1000
⊥
−
to 125000 Ohm
·
m. Let us consider the transverse
curves. They depend heavily
Fig. 7.28
The screening effect in the model shown in Fig. 7.27. Model parameters:
1
=
,
3
5Ohm
·
m
,
h
1
=
0
.
2km
,
=
1000
,
5000
,
25000
,
125000 Ohm
·
m
,
h
2
=
0
.
3km
=
2
,
3
=
100 Ohm
·
m
1Ohm
·
m
h
3
=
0
.
3km
,v
=
15 km
,
=
10000 Ohm
·
m
,
=
0
4
5
