In this work we approach the problem of the estimates of site seismic hazard for many towns and villages located in the Val d’Agri area (Southern Italy) that in the past were interested by many seismic events (Fig.1). The estimates have been carried out using a method that is based on the analysis of site seismic history extracted from macroseismic catalogs (Magri et al., 1994). To point out the influence of site effects two different procedures have been performed: in the first one seismic hazard estimates have been deduced from epicentral data only, in the second, intensity data observed at the site have been also considered. In tab.1 the results are shown, in the first column seismic hazard estimates deduced from epicentral data are reported, while in the second one seismic hazard estimates obtained not only from epicentral data, but also intensity dates observed at the site are indicated. The differences between the two estimates can be correlated with local variations of seismic response due to local geological features which are responsible for possible cases of amplification. In order to validate the presence of such correlation, seismic hazard estimates have been integrated by the use of site amplification measurements obtained using the Nakamura’s technique (Mucciarelli, 1998). This method is based on spectral analysis of the ratio between horizontal and vertical component of microtremors (Fig.2). Our findings reveal a good correlation between seismic hazard variations and the presence of site amplification effects. With a non-parametric test it is deduced a good correlation between hazard estimate augmentations and site amplification in the frequency band of building (Fig.3). The application of this kind of analysis to Val d’Agri area has pointed out that the estimates of site seismic hazard and site amplification measurements could be a powerful tool to solve many problem related to seismic microzonation.


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