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| Titel |
Physical modeling studying the travel times and reflection points of SH-waves reflected from transversely isotropic media with a tilted symmetry axis |
| VerfasserIn |
Young-Fo Chang, Chih-Hsiung Chang, Li-Chung Sun, Chia-Lung Chung |
| Konferenz |
EGU General Assembly 2011
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 13 (2011) |
| Datensatznummer |
250046961
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| Zusammenfassung |
| As an elastic wave propagates in a transversely isotropic media (TIM), SH-wave is the one possessed a pure mode polarization under reflection who does not convert to P- and SV-waves, and vice versa. The simplicity in SH-wave itself thus provides an easy way to view into the details of SH-wave propagation in a TI medium. In this study, we attempt to inspect the theoretical reflection moveouts of SH-waves reflected from a transversely isotropic (TI) layer with a tilted symmetry axis and verify the reflection point which could be shifted away from the common reflection point (CRP) in a common mid-point shooting (CMPS) by numerical calculations and physical modeling.
In a traveltime-offset analysis, the moveout curves in the TIM with different tilted symmetry axis are computed by a TI modified hyperbolic equation and the Fermat’s principle, respectively. It turns out that both of the computed moveout curves fit well to the one observed from physical models but in a vertical transversely isotropic (VTI) case for the Fermat’s principle method due to the numerical error. The reflection points for a CRP gather computed by Fermat’s principle show that they are close to CRP in both VTI and horizontal transversely isotropic (HTI) cases but shift away in other cases with a tilted symmetry axis. And the shifts are verified by the physical modeling. Additionally, our laboratory works also demonstrate the attenuation of SH-wave in a TIM is strongest for VTI case. As the symmetry axis is tilted from vertical to horizontal, the attenuation in the propagating energy is decreased. |
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