Variations in acceleration and excess pore water pressure during a seismic event are critical early-warning indicators of an impending dam collapse. To assess these variations, the seismic responses for three simplified model dams, based on cross-sections through a real earthen dam, were assessed with numerical simulations and centrifuge tests. A normalized root-mean-square error was utilized as a comparison index to assess the closeness between simulated and the recorded values. Assuming that the experimental records are reliable, the reliability of the numerical program was evaluated using this root-mean-square error estimation approach. Explanations for inconsistency between the two approaches are presented. The conclusions are drawn from the results of the three model dams.