P-SV and SH Two-dimensional Viscoelastic Finite-Difference Modeling Including Surface Topography

Summary Understanding seismic wave propagation in complex velocity model including lateral velocity changes and surface topography is important both to apply seismic exploration methods to mountainous region, and to evaluate seismic response at such region. We developed P-SV and SH two-dimensional (2D) viscoelastic finite-difference modeling methods including surface topography to investigate complex wave propagation at mountainous region. The finite-difference method is based on the second-order accurate in time, forth-order accurate in space, velocity-stress staggered grid scheme. Viscoelastic modeling is based on the Standard Linear Solid. Memory variables are introduced to eliminate the convolution in the viscoelastic constitutive relation. For irregular free surface condition, normal stresses perpendicular to the boundary and shear stresses on the free surface are set to zero. To calculate the particle velocities at the free surface, an image method is used to achieve the free surface condition of stresses. We applied the methods to calculate seismic response of P-SV and SH at a gravitational slope deformation. A 2D S-wave velocity model obtained from active and passive surface wave methods was used in the simulation. Calculated seismic responses are reasonably consistent with those observed from natural earthquakes.