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APPROXIMATE INVERSION OF AIRBORNE EM DATA FROM A MULTILAYERED GROUND1
- Source: Geophysical Prospecting, Volume 36, Issue 4, Jun 1988, p. 446 - 459
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- 27 Apr 2006
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Abstract
A complex transfer function c (or generalized skin depth) can be derived from data for the secondary magnetic field measured by a dipole system with small coil spacing at height h above the ground. This function has a useful property: For a uniform or layered ground, the real part of c yields the‘ centroid depth’z* of the in‐phase current system as a function of frequency.
This parameter can be combined with the apparent resistivity ρa derived by conventional methods. The function ρa(z*), if known over a broad frequency range, yields a smoothed approximation of the true distribution ρ(z) without an initial model. The relations between ρa(z*) and ρ(z) are studied for a number of multilayer models. An example of the application of the ρa*) algorithm to data from a groundwater survey is given.