Finite Difference Modelling of Rayleigh Waves with Nonuniform Grid Spacing
M. Causemann, Y. Pan and T. Bohlen
Event name: 24th European Meeting of Environmental and Engineering Geophysics
Session: Modelling, Inversion and Data-processing in Near Surface Geophysics C
Publication date: 09 September 2018
Info: Extended abstract, PDF ( 2.41Mb )
Price: € 20
The finite-difference (FD) method is widely used for the simulation of seismic-wave propagation. Since Rayleigh-wave wavelength usually increases with depth, we adopt a depth dependent nonuniform grid system in the FD modelling. The grid spacing generally increases exponentially with depth. The discretization of grids depends on two factors: the starting grid size and the increasing factor. By testing a homogeneous synthetic example, we chose the optimal discretization parameters by the tradeoff between accuracy and computational cost. As a rule of thumb, we choose a starting size of 2/3 of the horizontal resolution and an increase of grid spacing of 10 % for the modelling of shallow-seismic wave fields. This nonuniform grid leads to an increase of accuracy while reducing the computational cost to about 55% compared to a uniform grid system. We also apply the nonuniform grid to a laterally heterogeneous model to prove the applicability of nonuniform FD method to a complex model.