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such an asthenosphere uplift, we most likely can count only on the galvanic mecha-
nism of electromagnetic excitation. It seems that we have to revise inferences from
the papers cited above.
8.2.4 On the Quasi-Two-Dimensionality
of Asthenospheric Structures
Consider three-layered models including conductive sediments
1
and resistive
lithosphere
3
(Fig. 8.29). The astheno-
sphere surface has a three-dimensional rectangular uplift of length
l
, width 2
2
underlaid with conductive asthenosphere
v
and
amplitude
h
.
Let us test a set of these models at fixed parameters
1
=
10 Ohm
·
m
,
h
1
=
1km
,
h
2
=
h
2
=
99 km
,
49 km
,
h
=
50 km
,
3
=
10 Ohm
·
m
and
variable
parameters
2
=
1000
,
10000 Ohm
·
m; 2
v
=
30 km
,
l
=
30
,
150
,
300
,
360
,
450
,
600
,
750 km;
2
v
=
60 km
,
l
=
60
,
180
,
300
,
600
,
900
,
1200
,
1500
,
3000 km
.
Figure
8.30
exemplifies
the
apparent-resistivity,
impedance-phase
and
tip-
per
curves
obtained
in
the
three-dimensional
model
of
the
asthenosphere
2
=
·
,v
=
,
=
=
uplift with
10000 Ohm
m
30 km
l
60 km (elongation
e
1) and its
Fig. 8.29
A model with the
three-dimensional
asthenosphere uplift
