Valutazione di parametri connessi con lo studio della pericolosità sismica

Abstract

The Italian seismic catalogues contain information about earhquakes occurred in Italy; nevertheless only for a few of them it was possible to draw isoseismal maps. The aim of this work is to define for the events lacking of these the mean propagation patten of macroseismic effects by means of model derived from the available maps. The Italian territory was divided in 11 zones with similar seismotectonic characteristics. For each of these zones a mean azimuthal propagation model was computed by means of digitized macroseismic maps with epicentral intensity (Io) greater than or equal to VI degree of MERCALLI-CANCANI-SIEBERG scale (M.C.S.) for homologous isoseisms. These models were applied to those events for which it was not possible to draw maps. Italy was subsequently subdivided in elementary cells (0.1 x 0.1 degree) for each of which some parameters were evaluated, using the available isoseisms or the models, such as the number of macroseismic fewlt effects for each intensity degree, the maximum felt intensity and a synthetic index (C) summarizing all the previous effects. Each parameter was included in a map covering the whole territory to obtain more complete information for seismic hazards problems. Finlly the approach was applied to three important cities such as Milan, Bologna and Florence.