What is a SHAKE Analysis?
Several methods for evaluating the effect of local soil conditions on ground response during earthquakes are presently available. Most of these methods are based on the assumption that the main responses in a soil deposit are caused by the upward propagation of shear waves from the underlying rock formation. Analytical procedures based on this concept incorporating nonlinear soil behaviour, have been shown to give results in good agreement with field observations in a number of cases. Accordingly, they are finding increasing use in earthquake engineering for predicting responses within soil deposits and the characteristics of ground surface motions.
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A SHAKE analysis involves the following steps:

• Determine the characteristics of the motions likely to develop in the rock formation underlying the site, and select an accelerogram with these characteristics for use in the analysis. The maximum acceleration, predominant period, and effective duration are the most important parameters of an earthquake motion.
• Determine the dynamic properties of the soil deposit. Average relationships between the dynamic shear moduli and damping ratios of soils, as functions of shear strain and static properties, have been established for various soil types. Thus, a relatively simple testing program to obtain the static properties for use in these relationships will often serve to establish the dynamic properties with a sufficient degree of accuracy.
• Compute the response of the soil deposit to the base-rock motions. A one-dimensional method of analysis can be used if the soil structure is essentially horizontal.