Abstract: This paper presents a set of fully coupled finite element analyses of the response of the well known Lower San Fernando Dam during the 1971 earthquake.A critical state model incorporating the concept of state dependent dilatancy was employed to describe soil behavior over the full range of loading conditions encountered.The results show clearly that a flow slide occurred on the upstream side,and indicate that a downstream flow slide would occur too, if the downstream berm had not been constructed before the event.The analyses show also that the addition of an upstream berm could effectively prevent the upstream flow slide.