Scattering seismic waves from topographic features can lead to big changes in the displacements caused in free feld of canyons. This efect has been observed as a result of diferent earthquakes and extensive damages in certain areas of the site, rock failure, and landslides were experienced. In analysis related to scattering of seismic waves, in order to evaluate the efects of topographic resonance, canyons are generally assumed to be in an arbitrary and prismatic shape. However, in reality, canyons are often non-prismatic in line with the longitudinal axis of the canyon. Therefore, the narrowed areas of canyons are selected and studied as a suitable site for structures such as dams and bridges. This study provides the comparison between prismatic and non-prismatic canyons, evaluating the amplifcation pattern of diferent part on non-prismatic under P, SH and SV waves. The boundary element method was employed for the analyses as a very powerful numerical method for studying wave propagation issues. Also, the efect of soil types, direction of wave propagation and incident wavelength on the amplifcation of diferent part of canyon have been studied. The results of this study indicate that, in the parameters which have been studied, the incident wavelength has a signifcant infuence on amplifcation pattern, especially in the near parts of canyon
