Numerical simulation of seismic wave propagation produced by earthquake by using a particle method

Abstract

SUMMARY We propose a forward wavefield simulation based on a particle continuum model to simulate seismic waves travelling through a complex subsurface structure with arbitrary topography. The inclusion of arbitrary topography in the numerical simulation is a key issue not only for scientific interests but also for disaster prediction and mitigation purposes. In this study, a Hamiltonian particle method (HPM) is employed. It is easy to introduce traction‐free boundary conditions in HPM and to refine the particle density in space. Any model with complex geometry and velocity structure can be simulated by HPM because the connectivity between particles is easily calculated based on their relative positions and the free surfaces are automatically introduced. In addition, the spatial resolution of the simulation could be refined in a simple manner even in a relatively complex velocity structure with arbitrary surface topography. For these reasons, the present method possesses great potential for the simulation of strong ground motions. In this paper, we first investigate the dispersion property of HPM through a plane wave analysis. Next, we simulate surface wave propagation in an elastic half space, and compare the numerical results with analytical solutions. HPM is more dispersive than FDM, however, our local refinement technique shows accuracy improvements in a simple and effective manner. Next, we introduce an earthquake double‐couple source in HPM and compare a simulated seismic waveform obtained with HPM with that computed with FDM to demonstrate the performance of the method. Furthermore, we simulate the surface wave propagation in a model with a surface of arbitrary topographical shape and compare with results computed with FEM. In each simulation, HPM shows good agreement with the reference solutions. Finally, we discuss the calculation costs of HPM including its accuracy.

A mesh-free method with arbitrary-order accuracy for acoustic wave propagation

“…At the interface of the different spatial resolution, the radius of the influence domain is determined by the averaged spacing (Eqs. (2) and (3) in Takekawa et al (2012)). Fig.…”

“…They overcame the restrictions on the regular lattice through the augmentation in the number of the nearest neighbor points. Takekawa et al (2012) proposed a particle method to simulate seismic wave propagation induced by earthquakes. The method can introduce free-surface condition just by removing or ignoring any particles above the surfaces, and could be applied to computational rock physics problems (Takekawa et al, 2014a).…”

Free‐surface implementation in a mesh‐free finite‐difference method for elastic wave propagation in the frequency domain

“…The main difference from the FE methods is the cost for the pre-process, that is, the mesh generation process. The mesh-free method, which has the flexibility in the node arrangement (Takekawa et al 2012), would reduce the computational costs for the pre-process. Although any quantitative evaluation of computational costs is not straightforward because of the flexibility being a nebulous criterion, the reduction of the costs for the pre-process is the advantage of the mesh-free method over the FE method.…”

Numerical Study for Failure Behavior of Rock Masses Including Complex Free-surfaces Using a Particle Method

“…These advantages of the HPM would be developed to the analysis of the brittle failure of rock masses including complex free surfaces. Although the HPM has been applied to the estimation of the strong ground motion induced by an earthquake 8) , and the rock physical study for cracked media 9) , the applicability of the HPM to the brittle failure analysis has not been revealed yet.…”