GNGTS 2013 - Atti del 32° Convegno Nazionale

also distribute velocity and displacement waveforms, and to compute the associated ground motion parameters (peak and integral values). The dissemination of SYNTHESIS is performed through the web portal http://dyna.mi.ingv . it/synthesis/, where a fully relational database is stored. It can be explored through three groups of user-friendly interfaces, which allow performing queries on selected scenarios, stations and EXSIM (Motazedian and Atkinson, 2005) stochastic finite fault method An extended fault plane is divided in an appro- priate number of subfault, each of them is consid- ered as a point source (Boore, 1983; 2003) radiat- ing an ω spectrum. Ground motion produced by subfaults is summed in the time domain, with a proper time delay depending on the rupture time distribution, to obtain the expected ground mo- tion for the entire fault. Spectral shape depends on geometrical spreading, anelastic attenuation and kappa effects. In contrast to the previous ver- sion (FINSIM, Beresnev and Atkinson, 1987), this code implements the concept of dynamic corner frequency. Frequency-dependent crustal amplification function can be introduced to ac- count for wave amplification effect to the layered propagation media (Boore and Joyner, 1997). DSM (Pacor et al. , 2005) deterministic- stochastic approach with approximated Green’s functions An acceleration envelope is computed by isoch- rones theory for a 1D layered medium at each simulation site: the duration is defined by rupture propagation + crustal propagation. The deter- ministic envelope is used to taper a white noise time series that is then multiplied in the Fouri- er domain by an ω reference spectrum (Boore, 1983, 2003). The finite fault characteristic such as distance, radiation pattern and corner fre- quency are parameters of the spectrum. Frequen- cy-dependent site amplification function can be introduced to account local seismic site response. HIC (Gallovič and Brokešová, 2007) broadband hybrid integral-composite technique with full- wavefield Green’s functions The rupture process at the seismic source is de- scribed in terms of slipping of elementary over- lapping subsources with fractal number-size dis- tribution (fractal dimension 2), randomly placed on the fault plane. At low frequencies representa- tion theorem is employed assuming final slip dis- tribution composed from the subsources (provid- ing k -squared decay at high wavenumbers k ). At high frequencies the ground motion synthesis is performed by summing the point-source contri- butions from each subsource assuming ω Brune’s pulse radiation. Low and high frequency wave- forms are combined in the frequency domain taking into account an appropriate cross-over frequency band. Full-wavefield Green’s func- tions are computed by means of the DWN tech- nique in a 1D layered medium. Spectral attenua- tion is defined by quality factor and kappa value. Tab. 1 – Overview of the main characteristics of the simulation techniques that are included in the present release of the SYNTHESIS database (modified after Ameri et al. , 2011). 40 GNGTS 2013 S essione 2.1