Models of Deep Geoelectric Structures - Models and Methods of Magnetotellurics - page 308

⊥ , in relation to
the width of the asthenosphere uplift and the lithosphere resistivity. The observation site
is located at the epicentre of the uplift. The uplift half-width

Fig. 8.26 The transverse and longitudinal apparent-resistivity curves

v = 100 , 250 km; the litho-

sphere resistivity n - locally normal curves

outside and over the asthenosphere uplift. For the model from Fig. 8.22 with parameters
1 =

2 = 1000 , 10000 , 100000 Ohm · m; ˙ n , n and ¨ ˙ n , ¨

h 2 = 10 Ohm · m , h 1 = 1km , h 2 = 99 km , 49 km , h = 50 km , 3 = 10 Ohm · m

vation site is located at the epicentre of the uplift ( y = 0). Here the

⊥ -curve

transverse at v = 250 km and 2 = 1000 Ohm · m is practically

⊥ =

undistorted ( 3 . 53). It merges with the locally normal n -curve ¨ char-

acterizing the uplift. But with increasing 2 and decreasing v the screen-

⊥ = ing effect comes into play. At v = 250 km , 2 = 10000 Ohm · m( 1 . 12)

⊥ = ⊥ -curve departs from the

and v = 100 km , 2 = 1000 Ohm · m( 1 . 41) the

¨ n -curve and approaches the locally normal n -curve ˙ which characterises

⊥ =

the uplift surroundings. At v = 250 km , 2 = 100000 Ohm · m( 0 . 35) and

⊥ = ⊥ -curve merges with the ˙ v = n -

curve so that the asthenosphere uplift is actually screened. Quite different are the
longitudinal

100 km , 2 = 100000 Ohm · m( 0 . 14) the

-curves. At 2 ≥ · v ≥ ≥

1000 Ohm m and 100 km ( 2) they merge

n -curve. In a model with the uplift whose half-width is

with the locally normal ¨