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 24 for “"Vp/Vs"”.
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Automatic multicomponent image registration
… to problems unrelated to time shifts. Interval Vp/Vs ratios can be estimated from derivatives of time shifts that align reflections in multicomponent images, and these Vp/Vs ratios may be used to assess the accuracy of the automatic registration process. To improve the accuracy of estimated time …
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A fault-controlled geothermal system in Tarutung (North Sumatra, Indonesia)investigated by seismological analysis
The seismic structure (Vp, Vp/Vs, and Qp anomalies) contributes to the physical properties and the lithology of rocks and possible fluid distribution in the region. The Vp model images the geometry of the Tarutung and the Sarulla basins. Both basins have a depth of around 2.0 km. High Vp/Vs and …
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Crustal structure and evolution beneath the Colorado Plateau and the southern basin and range province
… systematic spatial variations in crustal Vp/Vs, crustal thickness and amplitude of P-to-S converted phases. Our results reveal that the BRP is characterized by a thin crust (28.2 ± 0.5 km), a mean Vp/Vs of 1.761 ± 0.014 and a mean amplitude (R) of P - to - S converted wave (relative to …
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Seismic tomography and surface deformation in Krýsuvík, SW Iceland
… volcanic system. We studied the seismicity and Vp, Vs and Vp/Vs ratio in this region by applying double difference tomography. Our tomography result indicates a low velocity zone at a depth of about 6 kin, directly beneath the earthquake swarm. At the same time, our relocation result delineates …
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Extracting Polar Anisotropy Parameters from Seismic Data
With Vp, Vs, and density well logs, we can do isotropic AVO forward modeling, using isotropic Zoeppritz equations or its approximations, and a wavelet extracted from the seismic data, to get synthetic seismic data. Compared with real seismic data, these synthetic data are scaled differently, and …
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Receiver function studies of crustal structure, composition, and evolution beneath the Afar Depression, Ethiopia
… of crustal thickness (H), crustal mean Vp/Vs [which is related to Poisson's ratio (Σ)], and the sharpness of the Moho (R) were determined using teleseismic data from 18 broadband seismic sensors that we deployed along a profile of 250 km long with a station spacing of ~ 10 km. The …
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Dynamic reservoir characterization using 4D multicomponent seismic data and rock physics modeling at Delhi field, Louisiana
… use PP and PS seismic data to jointly invert for Vp/Vs ratio and acoustic impedance. This technique has the advantage of adding more information to the non-unique inversion problem. Combining the inversion results from the monitor surveys of June 2010 and August 2011 provides acoustic impedance …
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Elastic-Wave Imaging Using P-P, Sh-Sh, and Sv-P Events: Modeling and Data Processing
… images, their corresponding velocity fields, and Vp/Vs values (Vp/Vs=6 on average). The resulting images are tied to the interpreted shallow 140 m well logs for quality control of the data processing and compared. The P-P and SH-SH images tie well with the conductivity logs and accurately show the …
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Stiffness characterization of mechanically-compressed cohesive soils using wave propagation
… are tested in order to characterize the Vp and Vs as a function of stress during K₀-consolidation. Resedimentation creates controlled, uniform specimens whose results can develop a backbone for velocity behavior independent of field heterogeneities and disturbance. The Vp and Vs results …
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Seismic studies of 3-D elastic and anelastic structure of crust and upper mantle in Western China
… estimation of the crustal thickness (H) and Vp/Vs ratio (κ). Our improved joint inversion results of S-wave velocities and crustal Vp/Vs ratios reveal mid-crustal low velocity, high Vp/Vs zones (possibly due to the presence of partial melt) in northern and southern Tibet, as well as in SE …
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Joint modeling receiver functions and autocorrelograms to estimate crustal structure in the presence of deep sediments.
… depth and the ratio of P velocity to S velocity (Vp/Vs). We refine receiver function methodologies for application to sedimentary basins, which is useful because basin structure introduces complexity to the receiver functions. First, we consider vertical autocorrelograms along with P receiver …
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A Multicomponent Walkaway Vertical Seismic Profile Experiment in a Heavy Oil Reservoir
A multicomponent walkaway VSP experiment was successfully processed and used to predict rock properties in a heavy oil reservoir. Post-stack image and pre-stack gathers were made for inversion and AVO analysis. A common shot reflectivity gather was also created for AVO study at the VSP well …
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Applicability of rock physics models in conjunction with seismic inverted data to characterize a low poro-perm gas-bearing sandstone reservoir for well location optimization, Bredasdorp Basin, SA
… bridge between the seismic observables (density, Vp and Vs) and reservoir parameters such as fluid content, porosity and mineralogy. In situ and perturbational log - derived forward modelling was performed. Both in situ and perturbational forward modelling were used to generate synthetic seismic …
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Seismic Tomography at Volcanic Rift Zones and Transpressional Plate Boundaries Askja Caldera and Macquarie Island
… presence of a cylindrical low-velocity and high Vp/Vs (P-wave velocity divided by S-wave velocity) zone beneath Askja caldera that is ∼3 km wide and extends to ∼8 km below sea level (bsl). Within this zone, a shallow low-velocity and high Vp/Vs anomaly is located ∼0.5 km bsl beneath the caldera. …
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Seismicity of the Bath County, Virginia locale
… to 6.53 km/sec at 50.7 km depth. The surface VP/VS ratio of 1. 74 is assumed for this entire layer. Beneath this layer is the mantle with P and S velocities 8.18 km/sec and 4.79 km/sec. The second of these models uses a linear increase in P velocity from 5.45 km/sec at the surface to 6.05 …
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Crustal structure beneath hi-climb seismic array in western Tibetan plateau from a generalized H-κ method
… crustal thickness (H) and average crustal Vp/Vs ratio (κ) are essential for understanding the tectonic setting and other fundamental geological questions. However, the traditional H-κ method may provide some questionable results in regions where crustal structures are complex and uncertain, …
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Continental Arc Processes in British Columbia and Earthquake Processes in Virginia: Insights from Seismic Imaging
… portion of the Coast Plutonic Complex has a 1.81 Vp/Vs ratio and is interpreted to have a bulk composition of mafic garnet granulite. This garnet granulite and large volumes of granodiorite-dominated melt were created by arc dehydration melting of amphibolite (or hydrated gabbro) in the …
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Fault plane structure of the 1995 Antofagasta Earthquake (Chile) derived from local seismological parameters
… radiated seismic energy distribution and the vp/vs ratios from a local earthquake tomograhpy study revealed some ideas about the composition and asperity generating processes. The investigation of 295 aftershock focal mechanism solutions supported the resulting fault plane structure and …
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Geophysical imaging methods for analysis of the Krafla Geothermal Field, NE Iceland
… melt region based on the P-wave, S-wave, and Vp/Vs ratio anomalies in the velocity model. Synthetic modeling of the relationship between the resistivity and velocity models demonstrated the complexities of integrating two data sets with signals of different wavelength and resolution. However, …
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A study of the structure of the Belgian crust by Moho determination and local seismic tomography
… 28 km underneath the Eifel Volcanic Province (EVP). These results are comparable to the results of other studies, like seismic reflection profiles and receiver function analysis. The degree of precision obtained underneath the Belgian onshore part of the BM, however, has not been reached before. …
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