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Tomography of dispersive media
1Department of Applied Analysis, Faculty of Information Technology and Systems, Delft University of Technology, The Netherlands.
The Journal of the Acoustical Society of America
|August 3, 2000
Summary
This study introduces a new phase-based tomography method to map seismic velocity variations in complex geological structures. The technique accurately reconstructs phase velocity, overcoming limitations of traditional traveltime methods for dispersive guided waves.
Area of Science:
- Seismology
- Geophysics
- Wave Propagation
Background:
- Wave propagation in layered structures exhibits frequency-dependent phase velocity (dispersion).
- Conventional traveltime tomography is unsuitable for dispersive media due to frequency-specific traveltimes.
- Reconstructing velocity variations in laterally varying media requires advanced tomographic approaches.
Purpose of the Study:
- To develop a tomographic method for reconstructing phase velocity of guided waves in laterally varying media.
- To explicitly account for the dispersive nature of guided waves in the tomographic inversion.
- To enable accurate velocity reconstruction where conventional methods fail.
Main Methods:
- A novel phase-based error criterion is employed, replacing traditional 'picked' traveltimes.
- The method explicitly incorporates the dispersive characteristics of guided waves.
- The algorithm is designed to be robust against interference noise.
Main Results:
- Phase velocity and source waveform are reconstructed with high accuracy (within a few percent).
- The developed tomographic method demonstrates robustness in the presence of noise.
- Application to seismic field data shows good correlation between reconstructed phase velocity and topography.
Conclusions:
- The phase-based tomography method effectively reconstructs phase velocity in dispersive, laterally varying media.
- This approach overcomes key limitations of conventional traveltime tomography.
- The method shows practical applicability and potential for geophysical exploration and hazard assessment.