Schmucker-Weidelt Lecture Notes, Aarhus, 1975 - MTNet

Tests for the assumption of a layered dis.tri.bution and the source
In addition there are certain constraints with regard to modu.lus,
phase and frequency dependence of the transfer functions. (cf. Sec.
2.6).
The compatability of MTS and GDS vertical sounding results can be
tested by the requirement that
asreadily seen form the second field equation rotE = -imp H .
-n o -n
If the wave-number structure of the source field is not lcnown, a
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Horizontal Gradient GDS can be formed: Observing that
-
the differentation of E = Cn impo H with respect to y and of
nx nY
= -iou C H wi.th respect to x yields
.Env o n nx
Since the electric surface field may be distorted by lateral non-
uniformi-ties even when their scale length and dep-th is smal.1 in
comparison -to the depth of. penetration, -the E-field observa.tj.oi~s
may be replaced by observing the tangen-tj.al- magnetic field also
at some dep-th d below -the surface, i.e. by conducting a 'vertical -
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Gradient GIIS. No knowledge of the wave-number st~uc-ture of the
source field w i l l be required, but"the resi;tivity po between the
' surface and the subsurface points of observations will be reqci-red.
Assume that the lateral gradients of IJnz are small in comparison
to the vertical gradients of H and H in v5.e~ of the condi.tion
n x nY
I -.
I ~ c [