عنوان مقاله [English]
This study focuses on modeling spatial variation of earthquake ground motion using numerical methods. wave passage effect, incoherence effect and local site conditions effect are the effective parameters on this phenomenon which its investigated in simple 2D topography and 3D models near to real topography. Among the numerical methods, the BEM is a very effective tool for dynamic analysis of linear elastic bounded and unbounded media. The method is very attractive for wave propagation problems, because the discretization is done only on the boundary, requiring smaller meshes and systems of equations. Seismic behavior of the site under the S wave at different frequencies are presented. For the different points on this topography, the pattern of displacement in time domain, pattern of amplification is presented. The effective parameters on topographic amplification are time lag and amplification. To determine the coherence function after too much analysis, statistical relationships for wave frequency content and site geometry are presented. Comparing results of this relationships with real recorded samples shows good accuracy and efficiency for calculating coherence support recorded data at canyon bed and the points above that. Using this statistical relationships and amplification functions due to existing records, the possibility of generating non-uniform accelerations using one record in canyon bed is investigated.