GNGTS 2013 - Atti del 32° Convegno Nazionale

The main geomorphological aspects are the presence of alluvial fans, slope debris, fluvial edges high among 10-20 m and a ridge. The available data required to make some of HVSR tests in all the studied municipalities. Particularly, we identified: 4 measuring points in Perosa Argentina, 7 points in Pinerolo, 4 points in Sant’Antonino di Susa and 4 points in Torre Pellice. Surveys. It was utilized the tri-directional high sensitivity seismometer Veloget 3D 1 Hz coupled with the Geode of Geometrics with 0.6 Hz minimal possible recording frequency to make the surveys. The sampling frequency of the signal was set to 125 Hz. Every measuring point was georeferred using a GPS (Garmin Etrex Vista). The seismometer was placed on the ground with particularly attention to the coupling. To ensure statistical reliability of the data, for each point the recorded time interval for each acquisition was among minimum of 18 minutes to a maximum of 46 minutes. The open source software Geopsy was applied (http:// www.geopsy.org/) to process the data and define the fundamental frequency of the site. In the study area within the municipalities of Perosa Argentina, Pinerolo, Sant’Antonino di Susa, Torre Pellice, were executed HVSR noise measurement to determine the resonance frequency of the site. In the municipality of Perosa Argentina the surveys were performed in four location. For all the measuring points (except P1) two recordings were carried out. In Fig. 1 all the HVSR curves acquired in Perosa Argentina show one or more clear peak frequency. P2a-P2b identified peaks due to contact of two layers with different acoustic impedance about 3-4 Hz and 8-9 Hz. P3a and P3b about 9-10 Hz. P1, P3a-P3b and P4a-P4b show a frequency peak between 1.5-2 Hz that is not reliable because the peaks are not due to stratigraphic resonance phenomena, but probably by some sources as an electromagnetic or human activities, that affect the quality of the results. In the municipality of Pinerolo the surveys were performed in seven locations. For Fig. 1 – HVSR curves obtained in: (a) Perosa Argentina, (b) Pinerolo, (c) Sant’Antonino di Susa, (d) Torre Pellice. 482 GNGTS 2013 S essione 2.3