Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 27 for “"shear wave splitting"”.
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Shear Wave Splitting Analyses in West Texas
We have analyzed shear wave splitting data from local earthquakes in the Permian Basin in West Texas to understand crustal stress and induced seismicity. The selected events of ML2.0 are recorded by the TexNet and USArray/Transportable Array (TA) stations. SWS parameters, the fast polarization …
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LATERALLY HETEROGENEOUS SEISMIC ANISOTROPY INVESTIGATED BY SHEAR WAVE SPLITTING ANALYSES
… and upper mantle. In this study, we utilize the shear wave splitting technique to investigate the piercing-point-dependent azimuthal anisotropy beneath the northeastern edge of the Sichuan Basin in central China, and the spatial and temporal variations of anisotropy near the 2019 M7.1 Ridgecrest …
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A new method to test shear wave splitting: improving statistical assessment of splitting parameters
Shear wave splitting has proved to be a very useful technique to probe for seismic anisotropy in the earth’s interior, and measurements of seismic anisotropy are perhaps the best way to constrain the strain history of the lithosphere and asthenosphere. However, existent methods of shear wave …
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APPLICATION OF MACHINE LEARNING IN GEOPHYSICS: RANKING TELESEISMIC SHEAR WAVE SPLITTING MEASUREMENTS AND CLASSIFYING DIFFERENT TYPES OF EARTHQUAKES
… two geophysical problems, ranking teleseismic shear splitting (SWS) measurements and classifying different types of earthquakes.</p> <p>For ranking teleseismic SWS measurements, we utilized a CNN-based method to automatically select reliable SWS measurements. The CNN was trained by …
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MANTLE FLOW AND TRANSITION ZONE DISCONTINUITIES BENEATH THE CARRIBEAN PLATE: CONSTRAINTS FROM SHEAR WAVE SPLITTING AND RECEIVER FUNCTION ANALYSES
… teleseismic SKS, SKKS, PKS (“XKS”) and local S wave splitting parameters is used to investigate lithospheric deformation and asthenospheric flow beneath the boundary zone of the North American and Caribbean plates and adjacent areas. A total of 4915 XKS and 1202 pairs of local S wave splitting …
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Mantle flow and lithosphere-asthenosphere coupling beneath the southwestern edge of the North American craton: constraints from shear-wave splitting measurements
… characteristics are revealed by 3027 pairs of splitting parameters measured at 547 broadband seismic stations. The western and southern edges of the North American craton show edge-parallel fast directions with larger-than-normal splitting times, and the continental interior is characterized by …
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Crustal modification by tectonic events and upper mantle anisotropy beneath the Midcontinent Rift and New Madrid Seismic Zone: insights from receiver function studies and teleseismic shear wave splitting
… earthquake activity. In this dissertation, shear wave splitting and receiver function techniques were employed to study the extent of crustal and upper mantle modifications beneath the New Madrid Seismic Zone (NMSZ) and the Midcontinent Rift (MCR). Shear wave splitting analysis in the MCR …
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Anisotropy and deformation in the Earth's mantle : seismological observations, geodynamical models, and laboratory experiments
… and deformation in the Earth's mantle, using shear wave splitting measurements, numerical models of geodynamical processes, and laboratory experiments on mantle minerals. I evaluate the performance of several methods for measuring shear wave splitting at broadband stations, and discuss how …
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Characterization and modeling of the stress and pore-fluid dependent acoustic properties of fractured porous rocks
… Models for stress-dependent P and S-wave seismic velocities of sandstone were then developed based on the assumption that stress-dependencies come from the nonlinear elastic response of micro-fractures contained in the sample under normal and shear loading. The contact shear stiffness …
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Seismic anisotropy and mantle flow beneath Africa and Arabia
… plumes. In this study we use continental scale shear-wave splitting (SWS) measurements to provide additional constraints on the various models of rifting, uplifting, and volcanism of the Cameroon Volcanic Line (CVL) and the Arabian plate. The splitting of P-to-S converted phases at the …
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Seismic anisotropy and mantle dynamics beneath the central and western United States
… the study, a total of 4138 pairs of well-defined shear wave splitting (SWS) parameters observed at 445 stations on the northern Great Plains show systematic spatial variations of anisotropic characteristics. Azimuthally invariant fast orientations subparallel to the absolute plate motion (APM) …
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Layered crustal and mantle structure and anisotropy beneath the Afar Depression and Malawi Rift Zone
… Accordingly, the first MTZ topography and shear wave splitting analyses were conducted in the region. The latter reveals largely plate motion-parallel anisotropy that is locally modulated by lithospheric thickness abnormalities adjacent to the MRZ, while the former reveals normal MTZ …
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Physical Modeling and Analysis of Seismic Data from a Simulated Fractured Medium
… and HTI anisotropic parameters (including shear-wave splitting parameter) were performed on P-wave re ection amplitudes from the top of the simulated fractured medium. Sensitivity analysis of the inversions results, including variations of the background velocity model and maximum incident …
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The earth's interior from both a seismological and petrological perspective
Shear-wave splitting measurements of teleseismic shear waves, such as SKS, have been used to estimate the amount and direction of upper-mantle anisotropy worldwide. One of the basic assumptions in making these measurements is that the anisotropy is confined to a single, homogeneous layer. In this …
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Hydraulic-fracturing induced seismicity in Alberta, Canada: Analysis and interpretation using dense local arrays
… techniques. Supplementary information, such as waveform data from broadband seismometers and an accelerometer that were co-located with the dense geophone array, is also used to aid the interpretation. In some cases, it is found that the magnitude-frequency distribution obtained from the …
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Seismic anisotropy and microseismicity: from crustal formation to subduction termination
… In the first part of my dissertation, I apply shear-wave splitting analysis to a microseismic catalogue (spanning the period 2008–2018) in the Northern Volcanic Zone of Iceland in order to investigate the relationship between seismic anisotropy and the tectonic stresses arising from extension …
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Seismic investigations of the northern Transantarctic Mountains
… this dissertation integrates Rayleigh wave surface wave tomography, downward continuation and wavefield decomposition, and seismic anisotropy studies to better characterize the structure beneath the northern TAMs and to assess uplift. Surface wave tomographic images indicate a …
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Elastic properties of salt: laboratory measurements, well-log analysis, and a seismic survey over the Hockley Salt Mine, Texas
… from the Goderich salt mine, Canada, demonstrate shear-wave splitting and compressional-wave variations which indicate cubic anisotropy. The stiffness values calculated for that are C_11=48.7 GPa, C_44=13.1 GPa , and C_12=11.9 GPa. Our samples from the Hockley and the Bayou salt mine have …
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Monitoring induced seismicity near the Wellington oil field, South-Central Kansas
… in pore pressure is monitored through time-lapse shear-wave anisotropy analysis. Since the onset of the observation period in 2010, the orientation of the fast shear-wave has rotated 90°, indicating a change associated with critical pore pressure build up. The time delay between fast and slow …
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