Result data of liquid sloshing inside a half filled rectangular tank described in the paper (Kha et al. (2024) Numerical Investigation of Liquid Sloshing in 2D Flexible Tanks Subjected to Complex External Loading. Under review in JFS journal), induced by an unidirectional seismic excitation. The ground horizontal component of acceleration of the 1994 Northridge earthquake recorded at Santa Monica City Hall station. The dataset contains: - the earthquake signal - the mesh of fluid and structure domains - the velocity and pressure fields of the fluid in flexible tank case - the volume fraction (alpha) for the two-phase flow in flexible tank case - the deformation fields of the structure in flexible tank case