Information Technology Reference
In-Depth Information
⎧
⎨
1
o
S
1
(
y
)
=
n
in the
S
1
-interval
=
o
S
1
S
1
(
y
)
2
(7
.
24)
⎩
h
2
=
n
,
in the
h
-interval
where
is the real frequency-independent
distortion factor
S
1
S
1
(
y
)
2
=
.
The apparent-resistivity distortion defined in accordance to (1.101) is
⎧
⎨
0
in the
S
1
-interval
⊥
=
⊥
−
log
log
n
=
S
1
S
1
(
y
)
(7
.
25)
⎩
=
.
log
2log
in the
h
-interval
⊥
-curve is undistorted, whereas its descending
branch is distorted (even dramatically distorted) being displaced from the locally
normal
Here the ascending branch of the
n
-curve by the frequency-independent distance log
(downward when
S
1
(
y
)
S
1
and upward when
S
1
(
y
)
<
S
1
).
Take a look at the transverse phase curve. According to (7.23) and (1.102)
>
0
in the
S
1
-interval
⊥
(
y
)
−
2
≈
(7
.
26)
in the
h
-interval
and
0int e
S
1
-interval
0int e
h
-interval
⊥
=
⊥
−
n
=
(7
.
27)
.
⊥
-curve are undistorted: they
Here the ascending and descending branches of the
merge with the locally normal
n
-curve.
The one-dimensional inversion of the amplitude
⊥
(
y
)-curves distorted by the
S
effect allows for determining the conductance
S
1
(
y
) of the upper layer but,
instead of the depth
h
to the conductive basement, it yields an
apparent depth
−
S
1
S
1
(
y
)
h
h
A
(
y
)
=
(7
.
28)
that may differ markedly from
h
. Errors in determining
h
cannot be avoided even
by the integrated one-dimensional inversion of the amplitude and phase curves. So,
in studying the relief of a highly conductive mantle at a depth of about 100 km we
may obtain a surface with strange zigzags caused by inhomogeneitis in sediments
at a depth of several tens or hundreds of meters. Looking through old journals, we
find numerous examples of such a naıve interpretation.
