1. A method comprising: obtaining electromagnetic data regarding a subsurface area of interest; identifying a region of anomalous resistivity within at least one resistivity image, the at least one resistivity image representing the subsurface area of interest and being derived from the electromagnetic data regarding the subsurface area of interest, a region of anomalous resistivity being a region with resistivity greater than or less than surrounding regions, which surrounding regions are referred to as background regions of the image; generating a 2D or 3D resistivity scenario model for the region of anomalous resistivity and its background regions, said scenario model having a plurality of non-background features selected to have a resistivity thickness product that matches to within a predetermined tolerance a resistivity thickness product of the region of anomalous resistivity in at least one dimension, wherein each non-background feature is too small to be resolved in said at least one dimension at the resolution of the electromagnetic data, and the resistivity thickness product in a particular dimension is the product of resistivity in that dimension multiplied by thickness in that dimension; and evaluating, using a computer, the resistivity scenario model to determine a fit with known electromagnetic data for the subsurface area of interest by either forward modeling the resistivity scenario model or inverse modeling using the resistivity scenario model as starting model for inversion.