Rasskazov L.N., Bestuzheva A.S., Sainov M.P., CHernysh A.S., Francesco Castelli and many others were engaged in studies of the stability of slopes under seismic impact. The paper considers numerical methods for assessing the seismic stability of embankment dams in a flat and three-dimensional problems in two ways: a direct dynamic method and a pseudo-static method. Several simulation cases are considered in a flat problem on a test problem using soil properties taken from a real site of an operating hydroelectric power plant. During the simulation, the following main simulation cases were considered: the natural stability; calculation without static components; calculation with static components; impact of free vibrations; calculation with full accelerogram; calculation with static deformation properties of soils; calculation with dynamic deformation properties of soils; calculation with undrained strength of soils; pseudostatic method. The analysis of the results showed that the calculation of the seismic stability of an embankment dam by the direct dynamic method gives the results that are closest to reality, in contrast to the pseudo-static calculation method.