Accurate seismic wave simulation requires to consider the Earth's viscosity and anisotropy characteristics. In seismic exploration, attenuation is generally assumed almost linear with frequency (therefore Q is independent with frequency). The Kjartansson's model can accurately describe the linear attenuation and constant-Q characteristics compared with the other approximate constant-Q model by superposition of linear elastic and stokes viscosity mechanism. In this study, we present a new viscoelastic anisotropic constitutive relation and derive the corresponding time-domain 2-D, 3-C wave equation for the general TI medium based on the constant-Q theory. The wave equation contain a fractional order of time derivative which is the key to implement attenuation and unifies viscoelastic and pure elastic cases into a single wave equation. Moreover, it avoid introducing memory variables, thus has a more simple form in comparison to viscoelastic anisotropic wave equations used before. In numerical examples, we use rotated staggered grid finite difference scheme to numerically solve the equations, with incorporating CPML absorbing boundaries, and the fractional derivatives are computed efficiently with an adaptive time memory central difference approximations method. The modeling results of an homogeneous model and the BP TTI model show well in agreement with the analysis of the theory and significant differences due to attenuation and anisotropic.
Presentation Date: Wednesday, October 19, 2016
Start Time: 2:20:00 PM
Location: 148
Presentation Type: ORAL
