WP3 — Numerical Techniques for Obtaining Full 3D Wave Regimes from the Geological to the Geotechnical Scale
Leader: Jean-François Semblat (ENSTA Paris)
WP3 studies the numerical techniques needed to couple source characteristics, the geological scale and the geotechnical scale, so that the resulting 3D wave regime preserves the surface-wave components already present at the geological scale as it becomes the incoming wave regime at the geotechnical scale. The work relies mainly on the Spectral Element Method (SEM) and the H-matrix accelerated Boundary Element Method (BEM).
Tasks
- Task 3.1 — From source radiation and directivity to basin impinging: improves numerical models of source radiation and directivity effects on the wavefield reaching alluvial basins, and assesses how wavefield polarisation changes before and after interaction with large-scale alluvial deposits. Fourier Continuation-based solvers are integrated with SEM or FEM to simulate seismic response in complex basin settings from regional to local scales.
- Task 3.2 — From basin effects to local geotechnical response variability: transmits the source/basin-coupled wavefield from Task 3.1 to the surficial geotechnical structure, combining lower- and higher-frequency components from different scales. Numerical models are validated against the seismic-motion database from WP2 in realistic alluvial basins, and a sensitivity analysis identifies which basin and soil features generate the largest surface-wave content and motion variability.
Milestones
- M3.1 — Improved numerical methods for 3D simulation of source-basin-soil interactions
- M3.2 — Earthquake hazard maps of the studied areas, including the induced surface waves
Deliverables
- D3.1 — Scientific report on the features of surface waves in alluvial basins, for various source mechanisms and basin configurations
- D3.2 — Scientific report on the amount of surface waves and the variability of ground motion at the geotechnical scale