Experimental measurements of the phase and group velocities of body waves in a transversely isotropic medium |
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| Authors: | Young-Fo Chang Mitch MC Chou Chih-Hsiung Chang |
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| Affiliation: | aInstitute of Applied Geophysics, National Chung Cheng University, Min-hsiung, Chia-yi 621, Taiwan, ROC;bDepartment of Materials Science and Optoelectronic Engineering, National Sun Yat-Sen University, Kaohsiung 804, Taiwan, ROC;cDepartment of Applied Physics, National Chiayi University, Min-hsiung, Chia-yi 621, Taiwan, ROC |
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| Abstract: | In this study, we perform an experimental result for measurements of the body wave phase and group velocities in transversely isotropic media (TIM) by through-transmission technique. After comparing the experimental and theoretical first arrival times of the waves, a difference between the phase velocity and group velocity is observed. When the ratio between propagation distance (d) of the wave and the diameter (D) of transducer is 2.4 for measuring phase velocity and the point probes configuration for measuring group velocity, the accuracy in velocity estimation can reach the limit of system's resolution. However if d/D is 7.8, the wave will propagate with an intermediate velocity between the phase and group velocities. The rapid change of the wave velocity and waveform for qSV-wave propagation with the group velocity has been observed at the propagation direction near the cusps. Therefore, in order to reduce the error in group velocity estimation of qSV-waves, the optimum directions are suggested at 20 and 60°. |
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| Keywords: | Phase velocities Group velocities Body waves Transversely isotropic medium |
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