GNGTS 2013 - Atti del 32° Convegno Nazionale

dispersive soils, while in reality it may refer to dispersive situations. When the dispersion effects on the MT curves do not cause any apparent incompatibility with the MT theory over layered structures, a dispersive MT response can as well be interpreted as a non-dispersive one and erroneously be modeled by a section, where the dispersive layer is totally suppressed (Esposito and Patella, 2009). MT data alone are not sufficient to distinguish polarization effects or can induce to see dispersion where is not present. An approach to solve this problem consists of the combinated interpretation of direct- current geoelectrical (d.c.) and MT data collected at the same site. References Balanis, C. A. Advanced Engineering Electro- magnetics , J. Wiley & Sons, New York, 1989. Cole, K. S. and R. H. Cole, “Dispersion and absorption in dielectrics,” J. Chem. Phys., Vol. 9, 341–351, 1941. Coppola, B., R. Di Maio, I. Marini, A. Merla, D. Patella, G. Pulelli, F. M. Rossi, and A. Siniscalchi, “Study of the Simplon area geothermal anomaly in the frame of a transalpine deep railway tunnel feasibili- ty project,” Underground Transportation Infrastructures, 93–102, ed. J. L. Reith, Balkema, Rotterdam, 1993. Di Maio, R., Patella, D., e Siniscalchi, A., “Sul problema del riconoscimento di uno Fig. 2 – MT apparent impedivity modulus and phase simulated responses for the A, Q, H and K three-layer sequences of Fig. 1, with the second layer affected by a Cole-Cole type dispersion. The black lines are the reference not dispersive MT responses. The flatting factor and principal time constant are fixed, c=0.75 and τ=100s, respectively, while the positive dispersion amplitude is variable with values m=0.1 (red lines), m=0.5 (green lines) and m=0.9 (blue lines). Fig. 3 – Variance of 2D models. The box at the center of the figure represents the position and the dimension of the buried body. 121 GNGTS 2013 S essione 3.2