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Thanks for pointing these out. For 2D slopes and 3D slopes, some attempts have been made to discuss the differences between the slope stability numbers and slip surfaces associated with the linear and nonlinear strength criteria. These differences between the nonlinear and linear solutions may change for slopes subject to different external influences, such as the water pressure and the earthquake. Our groups have made some investigations into the effects of pore-water pressure and outside water pressure on the nonlinear and linear solutions. Since few attempts have been made to illustrate the effect of seismic action on the difference between nonlinear and linear solutions for 3D soil slope stability, this study focused on the comparisons of the nonlinear and linear results (in forms of critical height and critical slip surface) with respect to different seismic loads.

As to the vertical acceleration, some studies have suggested that the vertical acceleration significantly affects the seismic performance and the permanent displacement of slopes when the horizontal acceleration is high and the slope is steep. But in the quasi-static method adopted in this study, the vertical acceleration can be reflected in the increase of gravitational acceleration. The results for analyzing the dynamic stability of slopes by using the vertical acceleration will be linear proportional relation with those for the static stability of slopes. Hence, the horizontal seismic acceleration will have more significant effects on the slope stability and the vertical acceleration was ignored in this study. Our subsequent study will further investigate the influences of the combined action of two seismic accelerations on slope stability.

In this study, the slope examples were presented in four homogenous dry clays. Though the total strength parameters derived by unconsolidated-undrained strength tests will be appropriate for water-bearing slopes undergoing earthquake, the effective or total strength parameters are both valid for clays in dry conditions. Hence, the nonlinear and linear strength parameters for the four clays can be selected as the soil bodies of slope examples in this study.

Following the reviewer’s comments, the authors will add some statements and make corresponding revisions in the subsequent revised manuscript.