GNGTS 2015 - Atti del 34° Convegno Nazionale

In Fig. 3 left panel, it is shown the areal distribution of site classes for the investigated area, whereas in the central panel, by interpolating these information through the Nearest Neighbor algorithm, a macro-zones map of the studied area was attained. The obtained results highlight that the main faults system in the studied area (Fig. 3, right panel) plays an important role in the seismic site response features of the lower eastern flank of Mt. Etna. Concluding remark. • A preliminary characterization of the local seismic response in the Etnean territory was made; • literature data were achieved in order to get information on the elastic parameters and lithology; • HVSR and HVNR were compared to test the reliability of ambient noise in Etnean area to obtain information on the soil fundamental periods; • through a simple 1D model, preliminary site amplification functions were attained and classified into 4 classes of a predominant-period site classification, trying in this way to overcome the limits usually showed by the average shear wave velocity of the upper 30 m (Vs,30); • a map site effects for the lower eastern flank of Mt. Etna was drawn up using the obtained classification; • long period seismic site effects corresponding to ET3 and ET4 classes seem to match the area of Timpe faults system and Pernicana fault; • the results highlight a strong contribution due to the presence of the oriented fractures linked to the fault fabric, and not only to stratigraphic effects, in causing local site effects. This imply that further analysis are needed to better constrain the obtained amplification functions. Acknowledgements. The present study was performed in the frame of the Volcanologic Project DPC-INGV ����� 2013- 2015 ������������������� �������� �� ��� ������������� ������� �������� ���������� ��� �������� ��������� ����������� “Multi-disciplinary analysis of the relationships between tectonic structures and volcanic activity” financially supported by the Italian Civil Protection Department (DPC). This paper does not necessarily represents the official opinion of the DPC. Fig. 3 – Left panel, map showing the class assigned to each measurement point. Central panel, map of the studied area obtained by interpolating the class assigned at each measurement point using the Nearest Neighbor algorithm. Right panel, shows the main faults in the studied area. 146 GNGTS 2015 S essione 2.2