Ground-supported tanks are used to store a variety of liquids. The fluid develops hydrodynamic pressure on walls and bottom of tank during an earthquake. This paper provides theoretical background for specification of impulsive and convective actions of fluid in liquid storage rectangular container by using analytical methods. Numerical model of tank seismic response - the endlessly long shipping channel was obtained by using of Finite Element Method (FEM), Arbitrary-Lagrangian-Eulerian (ALE), Fluid Structure Interactions (FSI) formulation in software ADINA. The results of the analytical methods and the numerical solution were compared for partially water filled channel grounded on hard soil or sub-soil 30 MNm–3. It was considered the horizontal ground motion of the earthquake in Loma Prieta.