Miaki Ishii
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View article: Body-wave speeds and polarizations in the presence of an initial deviatoric stress
Body-wave speeds and polarizations in the presence of an initial deviatoric stress Open
SUMMARY Body-wave speeds and polarization directions in a homogeneous and isotropic medium can be influenced by the presence of an initial deviatoric stress, which is conventionally ignored in seismic-wave propagation theories. To the firs…
View article: Seismic Wave Speeds Derived from Nuclear Resonant Inelastic X-ray Scattering for Comparison with Seismological Observations
Seismic Wave Speeds Derived from Nuclear Resonant Inelastic X-ray Scattering for Comparison with Seismological Observations Open
Nuclear resonant inelastic X-ray scattering (NRIXS) experiments have been applied to Earth materials, and the Debye speed is often related to the material’s seismic wave speeds. However, for anisotropic samples, the Debye speed extracted f…
View article: Application of Improved U-Net and ResU-Net Based Semantic Segmentation Method for Digitization of Analog Seismograms
Application of Improved U-Net and ResU-Net Based Semantic Segmentation Method for Digitization of Analog Seismograms Open
<p>Analog seismograms contain rich and valuable information over nearly a century. However, these analog seismic records are difficult to analyze quantitatively using modern techniques that require digital time series. At the same ti…
View article: Frequency‐Dependent <i>P</i> Wave Polarization and Its Subwavelength Near‐Surface Depth Sensitivity
Frequency‐Dependent <i>P</i> Wave Polarization and Its Subwavelength Near‐Surface Depth Sensitivity Open
Near‐surface structure is crucial to assessing seismic hazards and understanding earthquakes and surface processes yet is a major challenge to robustly image. Recently, an approach based on body‐wave polarization was introduced for constra…
View article: Near-surface compressional and shear wave speeds constrained by body-wave polarization analysis
Near-surface compressional and shear wave speeds constrained by body-wave polarization analysis Open
A new technique to constrain near-surface seismic structure that relates body-wave polarization direction to the wave speed immediately beneath a seismic station is presented. The P-wave polarization direction is only sensitive to shear wa…
View article: Back-Projection Imaging of Earthquakes
Back-Projection Imaging of Earthquakes Open
Back-projection analysis of earthquakes is a type of array processing that images the source of seismic waves coherently recorded at stations throughout the seismic network. The method was developed following the magnitude 9.2 Sumatra-Anda…
View article: Towards using direct methods in seismic tomography: computation of the full resolution matrix using high-performance computing and sparse QR factorization
Towards using direct methods in seismic tomography: computation of the full resolution matrix using high-performance computing and sparse QR factorization Open
For more than two decades, the number of data and model parameters in seismic tomography problems has exceeded the available computational resources required for application of direct computational methods, leaving iterative solvers the on…