This paper reports the applicability of using a skirted foundation system to study the behaviour of foundations with structural skirts adjacent to a sand slope and subjected to earthquake loading. The effect of adopted skirts to safeguard foundations and consequently the slope from collapse are studied. The skirts effect on controlling the horizontal soil movement and decrease pore water pressure generation beneath foundations and beside the slope during earthquake is investigated. This technique is investigated numerically using finite element analysis. A four story reinforced concrete building rests on a raft foundation is idealized as two-dimensional model with and without skirts. A two dimensional plane strain program PLAXIS, (with dynamic module) is adopted. A series of models for the problem under investigation were run under different skirt depths below the foundation and different lactations from the slope crest. Nodal displacements and element strains were analyzed for the foundation with and without skirts employing the studied parameters. The research results showed effectiveness of using the skirts in increasing the overall stability of the slope and foundations. This technique can be considered as a good method of controlling the horizontal movement of the slope and decrease the slope acceleration during earthquakes.