# The Characteristics of Seismic Rotations in VTI Medium
## 3 Synthetic Examples
Figure 8: Influence of \(\varepsilon\) on seismic records generated from the expansion source: (**a**) the seismic records of the 30 th trace; (**b**) the seismic records of the 90 th trace. Figure 2:0 Cont. Figure 2:1 Influence of \(\delta\) on seismic records generated from the expansion source: (**a**) the seismic records of the 30 th trace; (**b**) the seismic records of the 90 th trace. Figure 2:2 Influence of anisotropy parameters on amplitude spectra of the 90 th trace generated from the expansion source: (**a**) when \(\varepsilon\) varies; (**b**) when \(\delta\) varies. The seismic records, wave field snapshots, and FK spectra of different models are shown in Figures 5-7. Figure 5 demonstrates that, contributed by the velocity anisotropy,  
Figure 2:3 Influence of anisotropy parameters on phase spectra of the 90 th trace generated from the expansion source: (**a**) when \(\varepsilon\) varies; (**b**) when \(\delta\) varies. Figure 2:4 Influence of \(\varepsilon\) and \(\delta\) on peak values of the 90 th trace generated from the expansion source. both \(P\) and \(S\) waves existed in the components in the VTI media. The energy of \(S\) waves became stronger with increasing \(\varepsilon\), while the effects of \(\delta\) were almost invisible. The shape of wavefronts in \(R_{y}\) components became elliptical in VTI media, as seen in Figure 2:5 The eccentricities of the ellipse gradually increased with increasing \(\varepsilon\), while the eccentricity of the ellipse gradually decreased with increasing \(\delta\). There are obvious \(P\)- and \(S\)-wave energy groups in the rotational components in the FK spectra (Figure 7). With the increase of \(\varepsilon\), the energy of \(P\) waves decreased gradually, but became more concentrated at the same time, while the energy of \(S\) waves gradually increased. However, the FK spectra of rotational components were almost unchanged with increasing \(\delta\). We extracted and boosted the 30 th and 90 th traces' waveforms to study the effects of \(\varepsilon\) and \(\delta\) on the amplitude and phase of seismic waves, which represented the far and near offset traces, respectively, to analyze the dynamic characteristics in detail. With the increase of \(\varepsilon\), the amplitude and phase of the seismic waveforms showed obvious variations, as illustrated in Figure 2:6 In the near offset, with the increase of \(\varepsilon\), the \(X\) components changed slightly. The peak values of \(Z\) components decreased gradually, while those of \(R_{y}\) components increased gradually. However, in the far offset, the peak values of \(R_{y}\) components increased slightly, while the phase varied widely with the increase of \(\varepsilon\). The effects of \(\delta\) on waves' dynamic characteristics are shown in Figure 2:7 The effects of anisotropy on the \(X\) components were nearly negligible in the far offset, while the effects on the \(R_{y}\) components were obvious. The \(Z\) components changed substantially with the increase of \(\delta\) in the near offset. The waves on the rotational components changed more obviously than those on translational components with increasing \(\delta\). Furthermore, the influence of \(\varepsilon\) and \(\delta\) on different components is shown in the amplitude and phase spectra (Figures 10 and 11). We can conclude that the rotational components had more high-frequency information than the translational components, since the spectra of \(X\) components were mainly in the frequency range 60-100 Hz, \(Z\) components are mainly in the frequency range 70-110 Hz, and \(R_{y}\) components in the frequency range 80-120 Hz. The amplitude variation of the \(R_{y}\) components was much greater than that of the \(X\) components with the variation of \(\varepsilon\). On the \(Z\) components, the bandwidths of the wave fields became smaller, and the central frequencies became lower as \(\varepsilon\) increased. In addition, \(\delta\) had less of an influence on the amplitude spectra of the three components than \(\varepsilon\).