Information Technology Reference
In-Depth Information
11.3.3 Determining the Strike of the Regional Two-Dimensional
Background
By
way
of
example,
let
us
consider
the
magnetotelluric
parameters
N
mt
,
ske
w
B
obtained on a submeridional profile crossing the
Kirghiz Tien Shan (Fig. 11.35). The values of
w
ang
,
ske
w
S
,
and
ske
almost everywhere exceed
0.3, indicating a strong lateral inhomogeneity. But in some parts of the profile,
large values of
ske
|
N
mt
|
w
B
(
<
0.1-0.15), revealing a superposition of local 3D structures and regional 2D back-
ground. Note that almost all anomalies of
ske
w
S
(
>>
0.2) correlate with relatively small values of
ske
w
ang
≥
15
◦
. Figure 11.36 presents the impedance principal directions
PD
SE
defined by the
Swift-Eggers decomposition and the strike of the regional 2D background speci-
fied by the Bahr decomposition. The directions
PD
SE
vary chaotically, evidencing
a random noise caused by local 3D inhomogeneities, whereas the regional strike
gravitates to latitudinal direction with rather small deviations.
w
S
≥
0
.
3 are reflected in
ske
T
=
1600
s
PD
SE
STRIKE
148
148
152
N
152
156
156
163
163
165
165
171
171
S
Fig. 11.36
Impedance
principal directions along a
profile crossing the Kirghiz
Tien Shan; PD
SE
- defined by
Swift-Eggers method,
STRIKE - defined by Bahr
method
182
182
