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Fig. 8.35
Two-dimensional models of the asthenolith. The model IA-II contains an isotropic
asthenolith, the model AA-II contains an anisotropic asthenolith with alternating vertical layers
of higher and lower resistivity. The lithosphere resistance 1.5
10
8
m
2
·
Ohm
·
stable regions where the lithosphere resistance ranges up to 10
9
10
9
m
2
÷
5
·
Ohm
·
and the TM-mode is characterized by the strong screening effect (
w
<
2
d
where
=
√
S
sed
R
lit
is the adjustment distance,
S
sed
is
the sedimentary conductance and
R
lit
is the resistance of lithospheric strata sep-
arating an asthenospheric conductor from the sediments). Here the anisotropy-
isotropy equivalence may exist even at distances of about 300-500 km. Widening
w
is the asthenosphere width,
d
