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=
[
W
S
(
[
W
S
]
[
W
zx
W
zy
]
=
R
)] [
R
(
R
)]
R
)]
(4
.
83)
[
h
z
(
R
)][
Z
R
(
+
−
L
)] [
R
(
R
)] [
R
(
L
where [
R
(
)] is the rotation matrix:
cos
sin
[
R
(
)]
=
,
−
sin
cos
[
Z
R
(
R
)] is the regional impedance tensor:
0
Z
[
Z
R
(
R
)]
=
,
Z
⊥
−
0
W
S
(
L
)
are the Wiese-Parkinson matrix and the magnetic distortion
tensor in the regional and local coordinates:
W
S
(
R
)
and
h
z
(
R
)
=
0
W
zy
(
R
)
,
h
z
(
L
)
=
h
zx
(
L
)0
.
Test of (4.83) is performed simultaneously on the set of observation sites.
It reduces to hypothetical event analysis. By varying the horizontal magnetic
field polarization and monitoring the vertical magnetic field predicted for dif-
ferent events, we can find the regional strike and the phase of the regional
impedance.
4.5.3 The Berdichevsky-Kuznetsov Method
The (2D+2D)-superimposition problem can be greatly simplified if magnetic areal
observations are carried out synchronously with a base site located in the area with
the normal magnetic field and the strikes of two-dimensional structures are known
from tippers analysis.
Following Zhang et al. (1987, 1993) and Ritter and Banks (1998), we con-
sider the 3D superimposition model which contains two 2D structures of different
strike.
Examine the horizontally-layered model, in which two-dimensional horizontal
conductive prisms
P
and
P
with strike angles
are located at different
depths. The prisms are separated by thick highly resistive strata so that the galvanic
connection between them is virtually absent. At low frequencies the induction con-
nection is also absent. With these assumptions, we assume that each of the prisms
manifests itself as an independent body and the total magnetovariational effect of
both prisms is a sum of their partial effects. The model is excited by a plane electro-
magnetic wave incident vertically on the Earth's surface.
and
