Modélisation numérique des effets de site sismiques par approches modale et propagative

The amplification of seismic movement within sedimentary surface layers is a wellknown phenomenon in the field of seismology. It is entirely possible to comprehend this phenomenon via a simplified approach that enables directly studying the vibrational resonance of a valley in order to estimate its "fundamental frequency". In some cases however, it becomes necessary to analyze in detail seismic wave propagation In the sedimentary surface layers. The boundary element method, for example, makes it possible to evaluate the level of amplification at any point of a valley as a function of frequency. The results obtained from both approaches are then compared with measurements derived at sites in Nice and Volvi (Greece).