Amplification of seismic ground motion in the Tunis basin: Numerical BEM simulations vs experimental evidences

TL;DR

This study uses Boundary Element Method simulations to accurately estimate seismic wave amplification in the Tunis basin, aligning well with experimental data and analyzing key influencing factors like wave incidence and damping.

Contribution

The paper demonstrates the effectiveness of BEM simulations in modeling seismic amplification in a deep alluvial basin, highlighting parameter sensitivity and phenomena analysis.

Findings

BEM simulations accurately estimate maximum amplification frequencies.

Numerical results align with experimental observations of amplification levels.

Wave incidence and damping significantly influence amplification patterns.

Abstract

This paper aims at the analysis of seismic wave amplification in a deep alluvial basin in the city of Tunis in Tunisia. This sedimentary basin is 3000m wide and 350m deep. Since the seismic hazard is significant in this area, the depth of the basin and the strong impedance ratio raise the need for an accurate estimation of seismic motion amplification. Various experimental investigations were performed in previous studies to characterize site effects. The Boundary Element Method is considered herein to assess the parameter sensitivity of the amplification process and analyse the prevailing phenomena. The various frequencies of maximum amplification are correctly estimated by the BEM simulations. The maximum amplification level observed in the field is also well retrieved by the numerical simulations but, due to the sensitivity of the location of maximum amplification in space, the overall maximum amplification has to be considered. The influence of the wave-field incidence and material damping is also discussed.