GNGTS 2019 - Atti del 38° Convegno Nazionale

328 GNGTS 2019 S essione 2.2 All available geological and geophysical information in the basin (such as geological and velocity profiles, geotechnical parameters, thickness and geometry of the Quaternary sedimentary infilling) were collected in a QGis database in which locations of boreholes, downholes, gravimetric and geoelectrical surveys, geological and velocity profiles, seismic stations and noise measurement are georeferenced. Data analysis. The collected seismic data were analyzed to compute seismological parameters for seismic response analysis (earthquake and noise spectral ratios, duration lengthening of seismic signals) on a selection of 56 earthquakes belonging to the Central Italy seismic sequence 2016-2017 and recorded in the Montereale-Capitignano basin. In the first part of the analysis, variation of the PeakGroundAcceleration (PGA), PeakGround Velocity (PGV), Arias Intensity (AI) and Cumulative Absolute Velocity (CAV) parameters are analyzed. Then, Horizontal-to-Vertical (H/V) spectral ratios (both of earthquakes, i.e. HVSR, and of noise recordings, i.e. HVNR) and standard spectral ratio (SSR), ratio of the horizontal component of a target site on a reference site, are calculated by using Fourier spectra. Moreover, the duration lengthening of signal was studied to better understand its correlation with other site effect evaluation parameters. This method exploits the dependence on the frequency of the average group surface delay, as proposed by Sawada (1998). It is used to measure how the phase shift of the different wave packets varies according to the different frequency (delay time) at the same site, and it is compared with the delay in a reference site. Fig. 2 - Final plots of BA06 station. From top to bottom: Horizontal-to-Vertical Noise Ratio (HVnr); Horizontal-to- Vertical Spectral ratio (HVSR); average spectral ratio between stations BA06 and BA09 stations (SSR); polar plot showing the amplification along different azimuthal directions from 0.5 Hz (center of polar plot) to 5.0 Hz; delay between BA06 and BA09 stations.