Non-linear effects in seismic waves in high-energy earthquakes: A two-dimensional analysis for non-homogeneous isotropic media with a view towards the study of the 2009 L'Aquila earthquake.

This article investigates the limitations of linear models in describing seismic wave propagation during large-energy earthquakes, specifically focusing on the 2009 L'Aquila earthquake in the Aterno River Valley, central Italy. Using a two-dimensional viscoelastic isotropic continuum model with piecewise homogeneous materials representing soft and hard geological layers, the study compares linear and geometrically non-linear approaches under seismic excitation. Numerical simulations reveal significant differences between linear and non-linear predictions in deformation energy, kinetic energy, and ground accelerations, particularly near material discontinuities, with non-linear models providing results that better align with experimental observations. The findings suggest that non-linear effects are crucial for accurate seismic hazard assessment and structural design in inhomogeneous crustal regions, advocating for more sophisticated three-dimensional and material non-linearity models in future research.