Nonlinear seismic waves: A model for site effects

The aim of this paper is to propose a possible mathematical model of site effects that occur when seismic waves propagate through a sediment filled basin. The model is based on the mechanical properties of the medium (that we consider as a granular material) through which the seismic waves propagate. By looking for asymptotic solutions having the features of a progressive wave, we derive an evolution equation which is a modified Korteweg–deVries–Burgers equation containing also a nonlinear dissipative term. This equation is integrated numerically and the modelled site amplification is evaluated by using the smoothed spectral ratio between the propagated profile of the wave and the initial one.