GNGTS 2015 - Atti del 34° Convegno Nazionale

Furthermore the use of techniques of cluster analysis in the noise processing has enabled to recognize groups of similar HVSR curves and to relate them to similar interpretative seismic models. In many cases, the HVSR cluster analysis applied for microzonation studies of some towns in Sicily, showed good results, allowing to group peaks attributable to the same seismic structures. The comparison of the HVSR pattern with the information about outcropping formations allowed to assess the geological hypotheses on the heavily urbanized investigated areas. However obtained results underline how the most appropriate clustering algorithm for a particular problem often needs to be chosen empirically and how the choice of the partition is strongly linked to the choice of weights for the calculation of the distance and to the geological and stratigraphic knowledge of the area. Finally HVSR inversion demonstrates a valuable method, when used in accordance with certain criteria in the acquisition and processing, not only for the estimate of the site amplification effects, but also for the assessment of the main geological and tectonic structures that define the seismic bedrock and coverage deposits. References Adelfio G., Chiodi M., D’Alessandro A., Luzio D., D’Anna and G., Mangano G.; 2012: Simultaneous seismic wave clustering and registration. Computer and Geoscience, 44, 60-69, doi: 10.1016/j.cageo.2012.02.017. Barbarito, L.; 1999. L’analisi di settore: metodologia e applicazioni , Milano, Franco Angeli. Bonnefoy-Claudet S., Cotton F. and Bard, P.-Y.; 2006: The nature of noise wavefield and its applications for site effects studies . A literature review. Earth-Science Reviews, 79, 3-4, 205-227. doi: 10.1016/j.earscirev.2006.07.004. Capizzi P., Martorana R., Stassi G., D’alessandro A., Luzio D.; 2014: Centroid-based cluster analysis of HVSR data for seismic microzonation . Near Surface Geoscience 2014 - 20th European Meeting of Environmental and Engineering Geophysics, Athens, 14-18 September 2014, We Verg 02, doi: 10.3997/2214-4609.20142095. Fig. 3 – Depth of seismic bedrock (left) and seismic sections (right; yellow: seismic soil, green: bedrock). GNGTS 2015 S essione 3.2 55