Abstract This work presents an alternative methodology to establish seismic site classification. Also, the use of the new spectral parameters, named Spectral Threshold Displacement (STD) and Spectral Threshold Acceleration (STA), allow identifying the relevance of the displacement spectrum with the structural damage, which is also related to both the stiffness and drift of the structure. The analysis of the new spectral variables with respect to the response spectra defined by the seismic codes of Chile, Japan, Europe, and the USA demonstrates that local properties/conditions of soil deposits determine the damage caused by large earthquakes. The results set the context for a new methodology that uses the “Equivalent VS30-E” and the fundamental period TH/V (obtained with H/V spectral ratios) of the site as the key components to classify sites for seismic design