ABSTRACT
The effect of soft sediments on the dispersion of the earthquake ground motion is numerically investigated herein, to assess the effects of (i) the 3-D geological interfaces and (ii) of the spatial fluctuations of the mechanical properties. A source-to-site computational model is built-up, for a complex applicative case, configured as a 3-D soft basin embedded in outcropping bedrock. The transient wave-field is accurately computed by means of SEM3D, based on the spectral element method in elastodynamics and vectorized over large parallel supercomputers, for efficient scalability. Broad-band (0–7 Hz) earthquake simulations at regional scale (tens of kilometers) is performed, including the irregular edges of the basin. The spatial fluctuation of the shear modulus is integrated into the model as a multi-variate stationary random field, sampled at the computational nodes. The effect of soil heterogeneity is compared to the homogeneous counterpart, to assess the influence of the basin on the ground motion coherency.
