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 57 for “"Seismic imaging."”.
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Seismic imaging of the mantle transition zone
… integration with mineral physics data, the GRT seismic sections can put important constraints on the mantle temperature and mineralogy of the transition zone. Our GRT imaging results beneath the Central Pacific (including the Hawaii hotspot) reveal a more complicated mantle convection picture …
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A unified approach to complex seismic imaging problems
Two current challenges in seismic imaging are to obtain more detailed images of complex structures from reflection data and to constrain the regional structure of the Earth using wide-angle data. These are complex problems for which traditional methods fail because they are based on too many …
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Seismic imaging using internal multiples and overturned waves
Incorporating overturned waves and multiples in seismic imaging is one of the most plausible means by which imaging results might be improved, particularly in regions of complex subsurface structure such as salt bodies. Existing migration methods, such as Reverse Time Migration, are usually …
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Efficient seismic imaging with the double plane wave data
Seismic imaging is critical in providing the image of the Earth’s subsurface, and it plays an important role in hydrocarbon explorations. Obtaining high resolution images with accurate reflectivities and accurate positions of subsurface structures is the goal for exploration geophysicists. Reverse …
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A Comparative Case Study of Reflection Seismic Imaging Method
… on the earth interior. The quality of seismic images is highly variable depending on the complexity of the underground and on how seismic data are acquired and processed. One of the crucial steps in this process, especially in layered sequences with complicated structure, is the time …
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Seismic Imaging of the Global Asthenosphere using SS Precursors
… While this layer is often characterized by low seismic velocity and high seismic attenuation, the global structure of the asthenosphere remains poorly understood. In this dissertation, twelve years of SS precursors reflected off the top and bottom of the asthenosphere, namely, the LAB and the …
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Seismic Imaging of Earth’s Core-Mantle Boundary using Diffracted Waves
… most extreme velocity jump in the Earth’s radial seismic structure. In recent decades, seismological studies demonstrate that the seismic structure close to this boundary is far more complicated than a one-dimensional velocity model could describe. In particular, anomalous heterogeneities such as …
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Cooperative localisation in underwater robotic swarms for ocean bottom seismic imaging.
… research, and samples collection. Ocean-bottom seismic surveys are vital for oil and gas exploration, and for productivity enhancement of an existing production facility. Ocean-bottom seismic sensors are deployed on the seabed to acquire those surveys. Node deployment methods used in industry …
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Hierarchical Bayesian approaches to seismic imaging and other geophysical inverse problems
… these properties may vary spatially. In the seismic imaging problem, for example, where the objective is to estimate the earth's reflectivity, the reflectivity model is smooth along a particular reflector but exhibits a sharp contrast in the direction orthogonal to the reflector. In such …
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Wave propagation in complex media, scattering theory, and application to seismic imaging
Migration is a seismic imaging method that consists of creating a representation of the Earth's subsurface structure from the recording of seismic waves. Migration is essentially equivalent to solving an inverse scattering problem in structurally complex media. Conventional migration algorithms …
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Seismic Imaging of a Granitoid-Greenstone Boundary in the Paleoarchean Pilbara Craton
… bodies. Australian scientists acquired deep seismic reflection data crossing a granitoid-greenstone boundary. Their processing did not image the geologically mapped steep dip of the boundary because standard methods limit the maximum dip. A 37-km section of these data were reprocessed using …
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Solving Forward and Inverse Problems for Seismic Imaging using Invertible Neural Networks
… used optimization technique for subsurface imaging where the goal is to estimate the seismic wave velocity beneath the Earth's surface from the observed seismic data at the surface. The problem is primarily governed by the wave equation, which is a non-linear second-order partial …
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Seismic imaging with traveltime and waveform inversion: Naga Thrust and Fold Belt, India
… of traveltime and waveform inversion in depth imaging of seismic data with the help of two 2-D multichannel seismic lines, Reg-07 and PO-03, shot perpendicular to the trend of the Naga Thrust and Fold Belt (NTFB), India. I use both lines to demonstrate that a) a velocity model from traveltime …
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Understanding Arc-Continent Collision in the Banda Arc Through 3-D Seismic Imaging
… processes along-strike. Detailed knowledge of seismic structure is key to understanding this complex tectonic transition. A new Banda Arc Seismic Experiment composed of 30 broadband stations was carried out from March 2014 to August 2019 (~5 years) in the Timor-Leste and Nusa Tenggara Timor …
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Understanding Arc-Continent Collision in the Banda Arc Through 3-D Seismic Imaging
… processes along-strike. Detailed knowledge of seismic structure is key to understanding this complex tectonic transition. A new Banda Arc Seismic Experiment composed of 30 broadband stations was carried out from March 2014 to August 2019 (~5 years) in the Timor-Leste and Nusa Tenggara Timor …
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Seismic imaging of the lithosphere-asthenosphere boundary with a dense broadband array in central California
… Common conversion point (CCP) scattered wave imaging shows a strong negative velocity gradient (NVG) west of the San Andreas Fault (SAF) and a gap in a NVG horizon east of the SAF. This is interpreted as prominent arrivals at the base of a partially subducted microplate that become …
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Seismic Imaging and Velocity Model Building in the Thrace Region, Northwestern Turkey: A Case Study
The aim of this research is to apply several seismic processing and imaging techniques to a raw 3D-land dataset and examine the quality of the subsurface images. This study uses a 3D-seismic dataset in the Thrace region of northwest Turkey that was acquired by Turkish Petroleum in 2006 covering an …
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Continental Arc Processes in British Columbia and Earthquake Processes in Virginia: Insights from Seismic Imaging
… from a refraction and wide-angle reflection seismic survey across the Coast Plutonic Complex and Stikine terrane of British Columbia were inverted to derive two dimensional P and S-wave seismic velocity models of the crust and uppermost mantle. A felsic upper crust and a felsic to …
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Theory and application of source independent full wavefield elastic converted phase seismic imaging and velocity analysis
The recorded seismic signal contains full information about the source that generated the seismic waves and the path along which the seismic waves travel and interfere with subsurface. However, source information is not an explicit part of the seismic record and thus is a large source of …
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Seismic imaging and thermal modeling of active continental rifting processes in the Salton Trough, Southern California
… seafloor spreading has not initiated. Instead, seismicity, high heat flow, and minor volcanoes attest to ongoing rifting of thin, transitional crust. Recently acquired controlled-source seismic refraction and wide-angle reflection data in the Salton Trough provide constraints upon crustal …
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