Regularization on unstructured grids

The Geotechnologien project Multi-EM addresses the combination of different electromagnetic methods in a joint inversion approach to exploit their individual advantages. In Freiberg, we focus on the combination of the transient electromagnetic (TEM) and the DC resistivity method. We have implemented a new DC resistivity forward operator in MATLAB using unite elements on unstructured tetrahedral grids that can easily be combined with our already existing TEM software (Afanasjew et al., 2010). This code enables us to deal with even complex topography and to extract the derivatives, which are crucial for the inversion while retaining full control over the assembly process of the system matrix (Weißflog et al., 2012). For simplicity, we apply a regularized Gauss-Newton method in view of a combination of different electromagnetic methods in one inversion algorithm. We focus on an appropriate regularization technique that has been outlined in (Schwarzbach & Haber, 2013).