f Comparison between geological models based on resistivity data and resistivity-IP data

A geophysical study of a contaminated land area is presented. The main objective of this paper lies in the IP (induced polarization) technique — compared with EM and PVES (profile-vertical electrical soundings), what additional information on the geology and contamination is obtained when also the IP data is acquired? In glacial sediments lacking clay minerals, the induced polarization effect depends mainly on the grain-size distribution of the material and the resistivity of the pore-water. Vanhala (1997) measured large phase shifts to silts and fine-grained sands (Fig. 1), but small values to coarse sands and gravels, and also to clays. Very similar behavior has been reported also by Iliceto et al., (1982) and Dudas et al., 1991.