In our study, the selected random input parameters were the location of the water table (300 m behind the slope) derived from the hydrogeology considerations, the distributed force applied by the slabs pushing forward–which, in turn, depended on the variability ranges of the friction angle for the planes in the joint set J2, the width of the rock columns or spacing of the J2 family and the β angle–and the cohesions and friction angles for the sands and clays.