The aim of this presentation is to examine the relationship of the equivalent homogeneous shear moduli used in impedance models with stresses under the footing, through the use of scaled models in the centrifuge and an impact loading. The analysis of time and frequency vertical responses of footings reveals that reflections on the boundaries are negligible. The frequency response of a series of circular and square footings is shown to be rather easily-fitted with Wolf’s models for foundations on an infinite half-space with reasonably consistent parameters for masses, damping and shear moduli. The damping is nearly constant, yet significantly lower than in a prototype scale with real soil. The mass is fitted with a greater level of scatter. The correlation of shear modulus to the square root of the minimum mean stress appears to be better than that to the square root of the uniform stress under the footing
