Effects of 2D Random Velocity Perturbations on Short-Period (≤ 1s) Ground Motion Simulations; Application to Site Effect Assessment in the Nice (France) Sedimentary Basin

Date: 4/25/2019

Time: 06:00 PM

Room: Grand Ballroom

Numerical simulations of seismic wave propagation have become an essential tool for surface ground motion prediction and site effects assessment. For reliable numerical simulations of seismic ground motion, detailed velocity models are needed. Due to limited resolution of geophysical investigations, such models generally do not include small scale velocity variations. However, these variations can have an influence on short-period ground-motion, which is of interest for engineering applications. To overcome this limitation, statistical methods, characterized by autocorrelation functions, are often used to describe such small scale velocity variations.

Using two-dimensional spectral element simulations and a detailed realistic velocity model of the Nice area in France, we investigate the effect of short-wavelength (≤ 100m) heterogeneities (modeled using the Von Karman autocorrelation function) on surface ground motion at the scale of the sedimentary basin. Different combinations of autocorrelation function parameters are tested and their influence on the basin response is assessed. In particular, we show that increasing the size of velocity heterogeneities inside the basin leads to a decrease of the average ground motion amplification, computed using different realizations of the medium randomness.

Presenting Author: Flomin N. Tchawe

Authors