Comparison of Empirical and Numerical Site Responses at the Tito Test Site, Southern Italy

Abstract

The town of Potenza (Southern Italy) is one of the test sites for preparing ground-motion scenarios within the framework of the Italian Dipartimento Protezione Civile–Instituto Nazionale di Geofisica e Vulcanologia (DPC-INGV) 2004–2006 projects. An area in the neighboring village of Tito was selected to evaluate different techniques for estimating site effects involving a 40-m-deep instrumented borehole. This two-sensor vertical array records teleseismic, regional, and local seismicity. Close to the borehole, three seismological microarrays (utilizing short-period sensors\ud and digitizers with a high dynamic range) were installed in May 2005 to record seismic noise. Differing acquisition geometries allowed the checking of any dependency in the derived dispersion curves based on the adopted analysis method (extended spatial autocorrelation [ESAC] and frequency wave-number [F-K]). In general, the ESAC method appears to provide more reliable results in the low-frequency\ud range. Furthermore, the soil-velocity profiles obtained from the microarray data were compared with the S-wave velocity profile derived from down-hole measurements.\ud A good agreement was observed in the depth range well constrained by the data. Finally, empirical site responses were compared with those calculated numerically from the S-wave velocity profiles obtained from the microarray data. Although this comparison did not resolve a preference among the derived models, it showed the\ud importance of downgoing waves in modifying the site response at the Tito site

Site Effects Assessment in Bishkek (Kyrgyzstan) Using Earthquake and Noise Recording Data

“…However, in the south west of the study area, a local deepening of the basement to more than 3 km can be expected. (Ohori et al, 2002;Okada, 2003;Parolai et al, 2006;Parolai et al, 2007). The obtained dispersion curve (Figure 2b Furthermore, due to problems with power supply and the extremely low temperatures, it only worked for one month.…”

Love and Rayleigh waves dispersion analysis from microtremor measurements at Bevagna (Italy)

“…Moreover, the Rayleigh wave dispersion curve was estimated both with ESAC (Parolai et al, 2006) and f-k approaches, using only the vertical components of recordings. The ESAC and f-k analysis dispersion curves were compared and showed consistent estimate of the phase velocity of Rayleigh waves, with the well known discrepancies only in the lower frequency part (Parolai et al, 2007). However, the f-k plots analysis also offers the opportunity to verify st EAGE Conference & Exhibition -Amsterdam, The Netherlands, 8 -11 June 2009 if the requirements on the noise source distribution for the application of the ESAC analysis were fulfilled.…”

Seismic‐Wave Propagation in Shallow Layers at the GONAF‐Tuzla Site, Istanbul, Turkey

“…A common method used to find the quality factor Q is the spectral ratio technique (e.g., Gibbs et al, 1994;Parolai et al, 2007;Ge et al, 2009). It typically begins by computing the ratio of the Fourier spectra of isolated P and S waves between the surface and downhole seismograms, after taking into account instrument responses and other gain factors not related to attenuation.…”