| Abstract: | Empirical correlations between response spectra, magnitude, distance from the source and geological site conditions are introduced in a regional study of seismic hazard. A 350-year earthquake catalogue is treated by means of the statistics of extremes and both the spectral amplitudes (pseudovelocity) corresponding to a series of frequency bands are separately mapped, and the complete predicted response spectra calculated at some sites. Three kinds of geological site conditions are considered: thick and thin (less than 20 m deep) alluvium, and rock. A particular dependence of the results on the geographical distribution of earthquakes and on their magnitudes is commented. The seismic hazard of the study area is also computed by applying a traditional regression between peak ground velocity, magnitude and distance; a comparison with the seismic hazard given by the frequency dependent psuedovelocity indicates the extent of the uncertainty associated with the common practice of scaling response spectra directly from ground motion parameters. |
