3D Spectral Element Method simulations of the seismic response in the Caracas basin

E. Delavaud and Paul Cupillard and G. Festa and J. P. Vilotte. ( 2006 )
in: Proc. of the Third International Symposium on the Effects of Surface Geology on Seismic Motion, pages 515-522

Abstract

3D numerical simulation is a challenging issue for assessing the seismic response in complex media like sedimentary basins. In such models, the 3D geometry and the local geological features can result in significant wave amplifications and trapping of specific frequencies. These 3D effects must be taken into account for strong motion prediction and seismic risk assessment and illustrate the need for detailed basin models and accurate and flexible numerical techniques. A particular attention must be paid on the geometrical discretization and the incorporation of the velocities heterogeneities. Spectral Element Method (SEM) has become a reference method for the simulation of seismic waves propagation at regional and global scales. Unstructured hexaedral meshes allow to discretize complex basin geometries, velocity structures and topographies. However the mesh generation becomes a difficult and time consuming part of the modelling process. Even though unstructured hexahedral mesh generators, like CUBIT, offer new perspectives, assessing the quality of a mesh both in terms of geometrical and numerical accuracy is a challenging problem. We present 3D numerical simulations of the response of the Caracas (Venezuela) valley taking into account regional topography and complex 3D basin geometry. These simulations allow to assess such a strategy in a case where 3D effects from both the topography and the sedimentary structure can be observed. In particular, we analyze the influence of the discretization of the rock sediments interface, especially at its borders that can play a significant role in surface waves generation and therefore in the overall amplification effects.

Download / Links

BibTeX Reference

@INPROCEEDINGS{,
    author = { Delavaud, E. and Cupillard, Paul and Festa, G. and Vilotte, J. P. },
     title = { 3D Spectral Element Method simulations of the seismic response in the Caracas basin },
 booktitle = { Proc. of the Third International Symposium on the Effects of Surface Geology on Seismic Motion },
    volume = { 1 },
      year = { 2006 },
     pages = { 515-522 },
   address = { Grenoble, France },
  abstract = { 3D numerical simulation is a challenging issue for assessing the seismic response in complex media like sedimentary basins. In such models, the 3D geometry and the local geological features can result in significant wave amplifications and trapping of specific frequencies. These 3D effects must be taken into account for strong motion prediction and seismic risk assessment and illustrate the need for detailed basin models and accurate and flexible numerical techniques. A particular attention must be paid on the geometrical discretization and the incorporation of the velocities heterogeneities. Spectral Element Method (SEM) has become a reference method for the simulation of seismic waves propagation at regional and global scales. Unstructured hexaedral meshes allow to discretize complex basin geometries, velocity structures and topographies. However the mesh generation becomes a difficult and time consuming part of the modelling process. Even though unstructured hexahedral mesh generators, like CUBIT, offer new perspectives, assessing the quality of a mesh both in terms of geometrical and numerical accuracy is a challenging problem. We present 3D numerical simulations of the response of the Caracas (Venezuela) valley taking into account regional topography and complex 3D basin geometry. These simulations allow to assess such a strategy in a case where 3D effects from both the topography and the sedimentary structure can be observed. In particular, we analyze the influence of the discretization of the rock sediments interface, especially at its borders that can play a significant role in surface waves generation and therefore in the overall amplification effects. }
}