Аннотация:The subject of this study is the comparative analysis of the 2D and 3D approaches to thetsunami simulation. For this analysis an outer-rise earthquake along the Japan Trenchwas chosen. The vertical bottom displacement caused by this earthquake producesshort-wavelength waves, so in this case the 2D model may not be able to predicttsunami accurately. We performed 2D tsunami simulations with the use of the JAGURScode, based on the nonlinear shallow water equations with Boussinesq terms. Inthese 2D simulations we ignored the horizontal displacement effect, but we appliedthe Kajiura filter in estimating the sea surface displacements from the verticaldisplacement of the seafloor. In the 3D tsunami simulation we used Combined PotentialTsunami Model (CPTM), based on the linear wave equation with respect to the flowvelocity potential for the homogenius compressible ocean. The equations of the 3Dmodel were written in the curvilinear non-orthogonal depth-normalized sigma-sphericalcoordinate system. The 2D and 3D results coincides well, but in some points there aresmall discrepancies between them. To find the cause of these discrepancies weperformed additional numerical experiments. First numerical experiment was focusedon the tsunami generation process and especially on the applying of the Kajiura filter inthe 2D model. In the second numerical experiment we studied the role of the number ofthe vertical layers in 3D calculations in reproducing the dispersive effects of thetsunami propagation.This work was supported by the Russian Foundation for Basic Research (Projects 20-35-70038, 19-05-00351, 20-07-01098).