Ground motions can be altered when they encounter surface topographic irregularities. This study investigates a variety of topographic factors, such as the relative elevation, slope angle, and curvature, that can influence ground motion amplifications. The finite element analysis with absorbing boundary layer is performed using actual topography data and ground motions from earthquakes with magnitudes ranging from 3.8 to 9 recorded in Japan. While identifying the effect of wave velocity on ground motion amplification, we account for the variability in the topography and three sets of shear and longitudinal wave velocities by considering five cross-sectional profiles for the topographic models in the numerical analyses. We demonstrate that the topographic amplification factor, which is the ratio of the estimated spectral acceleration on the surface to the median spectral acceleration within the entire surface domain, is significantly influenced by curvature and relative elevation. We propose models to estimate ground motion amplifications using these two topographic factors — curvature and relative elevation — as variables.