“…The main aim with the research presented in this paper is to develop a computationally efficient inversion methodology for CSEM data that is able to preserve prior information about geological strata, and we will therefore apply a model-based representation (see, e.g., [2][3][4][5][6][7][8][9]) of the unknown electric conductivity field. Alternatively, a pixel-based representation (see, e.g., [10][11][12][13]) could have been used, although the tendency for smoothing out the resulting conductivity field makes it less attractive. Additionally, large computational costs are associated with running second-order gradient-based optimization algorithms with a pixel-based representation, due to the large number of parameters.…”