Impact of spatial variability of shear wave velocity on the lagged coherency of synthetic surface ground motions

The spatial incoherence of ground motion during an earthquake can have a significant effect on the dynamic response engineering structures such as bridges, dams, nuclear power plants and lifeline facilities. main objective this paper is to study anisotropic heterogeneities in soil layer overlying homogeneous bedrock lagged coherency surface motion. A set numerical experiments performed based 2D variability shear-wave velocities modeled stationary random field discretized by EOLE method (Expansion Optimal Linear Estimation). Seismic motions were simulated using FLAC2D software 1–25 Hz band for plane wave excitation with SV polarization. characterized horizontal vertical autocorrelation distances ranging between 5 20 m 1 2 m, respectively, coefficient variation velocity varying 5% 40%. synthetic seismograms calculated 9 parameter sets (100 realizations each) clearly show seismic waves scattering diffracted locally heterogeneities, generating large variations coherence mainly controlled velocity. Consistently existing models experimental data, curves decrease frequency receiver distance, however at rate which lower than that observed data. This difference probably due intrinsic attenuation not accounted simulations and/or our do reproduce complete wavefield. average each exhibit maxima within narrow bands caused vertically trapped body propagation properties model. interpretation supported data recorded Koutavos-Argostoli valley (Greece).