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 36 for “"seismic velocities"”.
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Seismic velocities in porous rocks : direct and inverse problems/
Thesis: Sc. D., Massachusetts Institute of Technology, Department of Earth and Planetary Science, 1978
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Surface Wave Inversion of the Upper Mantle Velocity Structure in the Ross Sea Region, Western Antarctica
… during Cretaceous to Paleogene rifting. Several seismic studies along the Transantarctic Mountains and Victoria Land Basin’s Terror Rift have shown a general pattern of fast seismic velocities in East Antarctica and slow seismic velocities in West Antarctica. This study focuses on the mantle …
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Electrical and seismic responses of shallow, volcanogenic, massive sulphide ore deposits
SP, resistivity/IP and seismic refraction responses of the Woodlawn Orebody and Mt.Bulga Deposit are examined and compared. Both exhibit similar responses produced mainly by uneconomic and disseminated sulphide mineralization and host rock features, demonstrating that the magnitude and character of …
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Modelling the controls on melt generation during continental extension and breakup
… mid-oceanic ridge basalt<br/>composition and the seismic velocity of the lower crust.<br/>The thickness of the lithosphere has a very large impact on the subsequent rifting style.<br/>Extension of a 125 km thick thermally and rheologically defined lithosphere that has no<br/>prior thinning …
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Evaluating the impact of deep-water channel architecture on the probability of correct facies classification using 3D synthetic seismic data
… but is unresolvable in exploration-scale seismic-reflection profiles. Forward seismic reflectivity modeling of a digital outcrop models is commonly used to explore how depositional architecture is interpretable in a filtered seismic response. One limitation of forward seismic reflectivity …
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ELASTIC, MICROSTRUCTURAL AND GEOCHEMICAL CHARACTERIZATION OF KEROGEN MATURITY FOR SHALES
… the kerogen content and its maturity affect the seismic properties for organic-rich shale reservoirs. The dissertation links geochemistry, seismic and petrophysics. The experimental part of the dissertation involves rock-eval pyrolysis, TOC estimation, and anhydrous pyrolysis for artificial …
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Data adaptive velocity/depth spectra estimation in seismic wide angle reflection analysis
In studying the earth with reflection seismics, one of the major unknowns is the velocity structure of the medium. Techniques used to determine the velocity structure commonly involve multi-channel arrays which measure the spatial as well as the time structure of the returning signals. The …
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Late Cenozoic basalts from the Basin-Range province, western United States
… by complementary variations in heat flow, seismic velocities, crustal thickness, magnetic anomalies and geologic setting. Alkali-olivine basalts from Japan and eastern Australia are analogous to those from the Basin-Range province both in composition and tectonic environment. It is …
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THE SEDIMENT AND CRUSTAL STRUCTURE OF THE SOUTHEASTERN UNITED STATES
… It has long been suspected that the current seismicity in the SEUS is related to zones of weakness inherited from past structural boundaries; however, the mechanisms that dictate the size and location remain poorly understood and the ground shaking hazard posed by widespread sedimentary …
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Methods for constructing 3D geological and geophysical models of flood basalt provinces
… to make them suitable for generating synthetic seismic data. Flood basalt provinces contain a number of different volcanic facies, distinguished by their outcrop appearance and physical properties. These include tabular-classic and compound-braided lava flows, intrusions and hyaloclastites. 3D …
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An Assessment of Hypocenter Errors Associated with the Seismic Monitoring of Induced Hydro-fracturing in Hydrocarbon Reservoirs
… single-well recording geometry used to monitor seismicity during hydro-fracture treatments could provide more accurate hypocenter locations and seismic velocities, improving general reservoir characterization. However, for the real, two-well data set obtained for this project, only S-wave picks …
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S-wave velocity structure beneath the Kaapvaal Craton from surface-wave inversions compared with estimates from mantle xenoliths
… craton of southern Africa are compared with seismic velocities estimated from approximately 100 mantle xenoliths brought to the surface in kimberlite pipes. As the xenoliths represent a snapshot of the mantle at the time of their eruption, comparison with recently recorded seismic data …
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A geophysical characterization of New River terrace deposits in Giles County, Virginia
… in lithology within the alluvial sediments. Seismic velocities (P-wave) obtained from reversed seismic refraction profiles range from 900-1700 meters/second, while apparent electrical resistivity values vary from 300-2000 ohm-meters. A 75 meter wide, east-west trending low resistivity zone …
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Lithospheric Structure Across the Northern Canadian Cordillera from Teleseismic Receiver Functions
A major change in seismic velocities between Earth’s crust and mantle is known as the Mohorovicic discontinuity (Moho). The depth of the Moho plays an important role in characterizing the overall structure of the crust and can be related to the tectonic setting of a region. Teleseismic P-wave …
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Continental Tectonics from Dense Array Seismic Imaging: Intraplate Seismicity in Virginia and a Steep Cratonic Margin in Idaho
Dense array seismic techniques can be applied to multiple types of seismic data to understand regional tectonic processes via analysis of crustal velocity structure, imaging reflection surfaces, and calculating high-resolution hypocenter locations. The two regions presented here include an …
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Geophysical and geochemical constraints on the evolution of oceanic lithosphere from formation to subduction
… I conclude that the continuous, low-magnitude seismicity located in diffuse pattern in a region with seismic velocities indicating ultramafic host rock suggests that serpentinization may play a role in microearthquake generation but the seismic network was not capable of providing robust focal …
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Seismic investigations of the northern Transantarctic Mountains
… recent Transantarctic Mountains Northern Network seismic deployment, 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 …
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Anomalies in P wave velocities in the Tampico embayment, Gulf Coast of Mexico
… this study was to discover relationships between seismic velocities and stratigraphic and tectonic zones of possible oil accumulation, by extrapolating velocity relations from known geologic features and oil fields in the Tampico Region. The original velocity data from the Tampico Region, …
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Geophysical and geochemical constraints on the evolution of oceanic lithosphere from formation to subduction
… I conclude that the continuous, low-magnitude seismicity located in diffuse pattern in a region with seismic velocities indicating ultramafic host rock suggests that serpentinization may play a role in microearthquake generation but the seismic network was not capable of providing robust focal …
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Laboratory analysis of restrenghtening on simulated faults
Seismic data show that stress drop increases with the logarithm of earthquake recurrence interval (1-5 MPa per decade time). If stress drop is taken as a proxy for fault strength, then the data suggest that faults restrengthen during the quiescent period of the earthquake cycle. Seismic surveys …
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