عنوان مقاله [English]
In this research, seismic wave scattering from a 3D canyon, considering the longitudinal changes of its cross section, is investigated using the parameter called as widening ratio. For this purpose three dimensional boundary element method is used and a special code in Fortran is developed to perform the seismic wave scattering analysis from arbitrary cross section canyon. Comprehensive sensitivity analysis is carried out to indicate the effects of the widening ratio on the patterns of the seismic wave's diffraction. The effects of wave characteristics including, frequency, type, direction of incident wave are investigated. The results are compared to the results of the prismatic canyon. The results indicates that the widening ratio has significant effects on the scattering pattern and therefore assuming prismatic canyon such as considered in the conventional analysis may lead to the significant errors in the estimation of seismic responses. It is shown that this effects is strongly depending on the frequency content of the seismic waves.