Magnetotellurics sounding over models of continuously varying conductivity

Abstract

In this paper, the analytical expressions for cagniard impedance are presented for a half space in which, as a whole or part thereof, the conductivity is assum ed to vary continuously with the vertical depth from the free surface (air earth boundary). Mathematically, the assumed variations are taken as (i) σ(z) = σ_oeα' z (ii) σ(z) = σ_o [ 1+ z/α]ⁿ where σ_o is the conductivity just at the surface and α and α' are constants. The impedance, thus obtained, can be utilized for preparing apparent resistivity master curves for the proposed models.