Abstract :
In the occurrence of an earthquake, local site conditions such as soil
characteristics, dimension of topographic irregularities, seismic bedrock depth, etc. as well
as characteristics of incident wave have important e ects on seismic ground response. In this
study, Finite Element Method (FEM) coupled with viscous boundaries is used to evaluate
the e ect of empty two-dimensional valleys on ampli cation or attenuation of seismic waves.
Parametric studies are carried out and the e ects of dimension of the topography, frequency
of the incident wave, and bedrock depth on the seismic ground response are considered using
non-linear method in a time domain analysis. Results are shown by means of horizontal
and vertical ampli cation ratios in valley span and its surrounding area. It is concluded
that displacement variation on ground surface due to topographical e ects is a considerable
factor to select a site location or design structures in the valley mount and its surrounding
area.
