Towards 3D ground motion simulation-based site amplification: a Wellington case study considering multiple basin geometries

Abstract

This paper presents a study on 3D ground motion simulation-based site amplification using the Wellington region of New Zealand as a case study. Several recent models of the Wellington sedimentary basin have been developed and are used in the simulations conducted as a part of this study to investigate the influence of basin geometry on site amplification. Location-specific site amplification factors for acceleration response spectra are presented at key locations throughout the Wellington CBD to illustrate how the simulated site amplification compare with observations. The simulations are found to produce amplification factors that have comparable level of amplification to observed amplification factors at deeper basin locations. Several limitations are also highlighted in this comparison. At shallow basin locations, the spatial resolution of the simulations conducted are not able to properly capture the basin response. Due to an enforced minimum S-wave velocity of 500 m/s in the simulations, the periods of spectral peaks are not accurately matched between simulation and observation. This provides motivation for further research into improvement and advancements in the simulations.