Spatial Variation of Magnetotelluric Field Components in simple 2D and 3D Environments

Abstract

The spatial variation of magnetotelluric field components over a buried three-dimensional conductive inhomogeneity is investigated numerically. The E-polarization mode electromagnetic field components were computed for different aspect ratios of the inhomogeneity and for different frequencies of the incident waves. The results show that as aspect ratio of the inhomogeneity is reduced the spatial variation of the electric field component E_x is reduced and that of the magnetic field component H_y is increased. Furthermore, the variation of Hy is strongly influenced by frequency as aspect ratio is reduced. Familiarity with these variations is important in understanding the behaviour of theoretically computed apparent resistivities which are useful in the interpretation of magnetotelluric field measurements for investigating geologic structures.

KEYSWORDS: Spatial variation, E- polarization mode, Magnetotelluric field components, Electromagnetic field components, Three – dimensional, Two – dimensional, Aspect ratio.