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    Novel Surface Wave Imaging Methods

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    ZhaolunLiuThesis_final.pdf
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    12.80Mb
    Format:
    PDF
    Description:
    Dissertation
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    Type
    Dissertation
    Authors
    Liu, Zhaolun cc
    Advisors
    Schuster, Gerard T. cc
    Committee members
    Peter, Daniel cc
    Santamarina, Carlos cc
    Bruhn, Ronald L.
    Program
    Earth Science and Engineering
    KAUST Department
    Physical Science and Engineering (PSE) Division
    Date
    2019-09
    Permanent link to this record
    http://hdl.handle.net/10754/656869
    
    Metadata
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    Abstract
    I develop four novel surface-wave inversion and migration methods for reconstructing the low- and high-wavenumber components of the near-surface S-wave velocity models. 1. 3D Wave Equation Dispersion Inversion. To invert for the 3D background S-wave velocity model (low-wavenumber component), I first propose the 3D wave-equation dispersion inversion (WD) of surface waves. The results from the synthetic and field data examples show a noticeable improvement in the accuracy of the 3D tomogram compared to 2D tomographic inversion if there are significant 3D lateral velocity variations. 2. 3D Wave Equation Dispersion Inversion for Data Recorded on Rough Topography. Ignoring topography in the 3D WD method can lead to significant errors in the inverted model. To mitigate these problems, I present a 3D topographic WD (TWD) method that takes into account the topographic effects in surface-wave propagation modeled by a 3D spectral element solver. Numerical tests on both synthetic and field data demonstrate that 3D TWD can accurately invert for the S-velocity model from surface-wave data recorded on irregular topography. 3. Multiscale and layer-stripping WD. The iterative WD method can suffer from the local minimum problem when inverting seismic data from complex Earth models. To mitigate this problem, I develop a multiscale, layer-stripping method to improve the robustness and convergence rate of WD. I verify the efficacy of our new method using field Rayleigh-wave data. 4. Natural Migration of SurfaceWaves. The reflectivity images (high-wavenumber component) of the S-wave velocity model can be calculated by the natural migration (NM) method. However, its effectiveness is demonstrated only with ambient noise data. I now explore its application to data generated by controlled sources. Results with synthetic data and field data recorded over known faults validate the effectiveness of this method. Migrating the surface waves in recorded 2D and 3D data sets accurately reveals the locations of known faults.
    Citation
    Liu, Z. (2019). Novel Surface Wave Imaging Methods. KAUST Research Repository. https://doi.org/10.25781/KAUST-ZEJ19
    DOI
    10.25781/KAUST-ZEJ19
    ae974a485f413a2113503eed53cd6c53
    10.25781/KAUST-ZEJ19
    Scopus Count
    Collections
    PhD Dissertations; Physical Science and Engineering (PSE) Division; Earth Science and Engineering Program

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