A new concept of Newmark's sliding block method for predicting permanent displacements of earth slopes subjected to seismic loading is presented. Horizontal ground acceleration is used as input motion to move a rigid circular sliding block inside an embankment. The effect of the maximum ground horizontal acceleration, velocity and displacement; the maximum value of the response spectrum of the earthquakes for acceleration, velocity and displacement, the values of the response spectrum corresponding to the maximum permanent displacement; and spectrum intensity as well as predominant frequency of the earthquake acceleration on the permanent displacement are studied.