Three Step Depth Focussed Inversion as a Tool to Resolve Small Resistivity Contrasts by ERT

In more recent times Electrical Resistivity Tomography (ERT) has become a valuable tool for many environmental research themes. Within these topics the resistivity contrasts of the different layers and zones are of importance, i.e. sand, clay, water salinity and preferential infiltration pathways are quite small. Inclusions with such small resistivity contrasts to the surrounding are difficult to resolve by ERT inversion and typically the following problems occur: 1.) the true resistivity contrasts are underestimated 2.) the size of the anomalous zone is overestimated 4.) fake anomalies arise beside and between the true anomalous zones. 4.) surface heterogeneities infer fake anomalies into the subsurface.