Three-dimensional frequency-domain modeling of airborne electromagnetic responses

Abstract

A novel three-dimensional (3D) frequency-domain modeling code has been implemented for airborne electromagnetic (AEM) simulations. The code is based on the volume integral equation (IE) solution to Maxwell's equations. To verify the code we consider three earth models of practical interest: (1) a 3D elongated body (dyke) residing in a layered earth; (2) faulted half-space (vertical contact) without, and, (3) with topography. Comparison of the code with a staggered-grid finite-difference solution for these models produces results in excellent agreement. In addition we have simulated responses that were previously numerically intractable, such as anisotropic and high-contrast 3D targets. We believe that our code is an efficient tool for AEM applications; as an example, for a model of a 1 Wm body in a 100 Wm half-space the code takes 8 minutes on 100HHz Pentium PC per AEM system position when the body is discretised into 1500 cells.