1D Time Domain Electromagnetic Interpretations Over 2D / 3D Structures

Time domain electromagnetic soundings have been calculated over 2D / 3D structures in a layered halfspace and hereafter inverted using a 1D least squares time domain code. The forward calculations are done in the frequency domain and the subsequent transform to time domain is performed using fast digital filters. The study focuses on typical hydrogeological models. The investigated models include a resistive dyke, a resistive beam and resistive block structure with edges with varying slopes in a conductive layered halfspace with an overburden. The 1D interpretations of the 2D / 3D responses show that the vertical resolution is reduced and the resistivities are smeared out. The 2D / 3D responses over models with a resistive body in a conductive host is easily fitted with the 1D models whereas it is not possible to fit the responses from good conductors in a resistive host very well.