SOLUTION OF MAGNETOTELLURIC FIELD EQUATIONS FOR A TWO-DIMENSIONAL, ANISOTROPIC GEOELECTRIC SECTION BY THE FINITE ELEMENT METHOD

We assume that one of the principal axes of anisotropy is coincident with the direction perpendicular to the stratification, the another is parallel to the structural strike. Under these conditions, a variation equation of the magnetotelluric field for a two-dimensional anisotropic geoelectric section is given in this paper. We solve the variation equation by means of the finite element method: Dividing the entire region into many triangular elements and interpolating with a quadratic function in each element the variation equation is converted into a system of linear algebric equations. By solving the equation system we can obtain the field values on the nodes and calculate the derivatives of the field. Prom these values the apparent resistivity on the ground surface can be calculated.The calculation example shows that the magnetotelluric field in the case of aniso-tropy is obviously different from that of isotropy for wave H_x (x parallel to the structural strike).