STRUCTURE AND SEISMIC RESPONSE OF EXTENDED CONTINENTAL-CRUST - STOCHASTIC-ANALYSIS OF THE STRONA-CENERI AND IVREA ZONES, ITALY

A two-dimensional stochastic seismic model of the crustal cross sectio n exposed in the Strona-Ceneri and Ivrea zones, northern Italy, was de rived from geologic maps and petrophysical data with techniques used i n microfabric analysis. The model has a layered self-affine structure, which agrees with the intrinsic scale independence of geologic phenom ena. Synthetic seismograms from this model replicate many pertinent fe atures observed in deep seismic reflection data and allow insight into crustal structure: (1) reflectivity depends on the lithological popul ations present and their distribution within a crustal unit; (2) trans parent zones within the reflective lower crust can arise from metamorp hic reactions; (3) the transition from upper to lower crust may be a c hange in small-scale seismic fabric rather than a first-order seismic discontinuity.