Simulating propagation of separated wave modes in general anisotropic media, Part I: qP-wave propagators

1.2 Two-layer TI model

This example demonstrates the approach on a two-layer TI model, in which the first layer is a very strong VTI medium with $v_{p0}=2500 m/s$ , $v_{s0}=1200 m/s$ , $\epsilon=0.25$ , and $\delta=-0.25$ , and the second layer is a TTI medium with $v_{p0}=3600 m/s$ , $v_{s0}=1800 m/s$ , $\epsilon=0.2$ , $\delta=0.1$ , and $\theta=30^{\circ}$ . The horizontal interface between the two layers is positioned at a depth of 1.167 km. Figure 6a and 6d display the horizontal and vertical components of the displacement wavefields at 0.3 s. Using the pseudo-pure-mode qP-wave equation, we simulate equivalent wavefields on the same model. Figure 6b and 6e display the two components of the pseudo-pure-mode qP-wave fields at the same time step. Figure 6c and 6f display pseudo-pure-mode scalar qP-wave fields and separated qP-wave fields respectively. Obviously, residual qSV-waves (including transmmited, reflected and converted qSV-waves) are effectively removed, and all transmitted, reflected as well as converted qP-waves are accurately separated after the projection deviation correction.

ElasticxInterf,PseudoPurePxInterf,PseudoPurePInterf,ElasticzInterf,PseudoPurePzInterf,PseudoPureSepPInterf
Figure 6. Synthesized wavefields on a two-layer TI model with strong anisotropy in the first layer and a tilted symmetry axis in the second layer: (a) x- and (d) z-components synthesized by original elastic wave equation; (b) x- and (e) z-components synthesized by pseudo-pure-mode qP-wave equation; (c) pseudo-pure-mode scalar qP-wave fields; (f) separated scalar qP-wave fields.

Simulating propagation of separated wave modes in general anisotropic media, Part I: qP-wave propagators