Physical Sciences and Mathematics Commons^™

Revealing The Core Dynamics Of Vesta: Insights From Experimental Investigations Of Electrical Resistivity And Thermal Conductivity, Oluwasanmi A. Orole Mr

Electronic Thesis and Dissertation Repository

Insights from high pressure and temperature experiments involving in-situ measurements of the electrical resistivity of Fe-5wt%Ni at temperatures of up to 2000 K, under pressures of 2-5 GPa in a 1000-ton cubic-anvil press have been used to reveal Vesta’s core dynamics. The Wiedemann–Franz law was used to calculate the thermal conductivity from the measured electrical resistivity data. Comparing the findings of this study with prior investigations on both pure Fe and Fe-10wt%Ni indicates that an increase in Ni ranging from 0-10wt% has negligible effect on the electrical resistivity of Fe alloys. By comparing the range of estimated heat flux through …

Empirical Nonlinear Site Response Applicable To Greater Vancouver, British Columbia, Natalia Gomez Jaramillo

Electronic Thesis and Dissertation Repository

In Greater Vancouver, strong earthquake shaking has not been recorded to quantify expected nonlinear soil response. Earthquake horizontal to vertical spectral ratios (eHVSR) are evaluated at seismic stations located at the edges or deeper center of sedimentary basins in Mexico City, the Kanto basin and Anchorage with available weak-to-strong motion recordings that have similar linear site response to Greater Vancouver to constrain the expected nonlinear soil response for future large earthquakes affecting Greater Vancouver. The empirical results confirm that the very low fundamental frequency (f₀ < 0.6 Hz) at deep Fraser River delta sites will be less affected by strong shakings and suggest that for Fraser River delta edge sites the amplification at the predominant frequency (f₁) could increase up to 1.77 times with a strong event. This thesis’ …

Petrophysical Properties Of The Hed Meteorites And The Bushveld Igneous Complex: Implications For Future Asteroid Prospecting Missions, Lukas Louwerse

Electronic Thesis and Dissertation Repository

In this work, I make a quantitative and mineralogical comparison of Howardite-EuctriteDiogenite (HED) meteorites with terrestrial samples from the Bushveld Igneous Complex (BIC) to assess how geophysical surveys of 4 Vesta or of V-type asteroids could detect BIClike ore deposits. Petrophysical methods in this work include bulk and grain density, derived porosity (using helium pycnometry, the Archimedean method, and X-ray micro-computed tomography), magnetic susceptibility, induced polarization and resistivity, and P-wave velocity. Mineralogical methods in this work include optical microscopy, micro X-ray diffraction, micro X-ray fluorescence element mapping, and electron beam methods. Howardite NWA 15199 was classified as part of this …

Topographic Effects Of Shallow Crustal Earthquakes In The Greater Vancouver Region, Alex Vanderhoeff

Electronic Thesis and Dissertation Repository

Vancouver has a high seismic risk due to the proximity of the city to the Cascadia subduction zone offshore, the soft sediments the metropolitan region overlies, and the mountainous topography nearby. The soft sediments and mountainous topography could cause an increase in shaking due to the sedimentary basin, topographic resonance and constructive/destructive interference, respectively. Numerical three-dimensional (3D) wave propagation simulations (WPS) were run using a finite difference scheme developed by Peterson and Sjogreen (2012), Seismic Waves, 4^th order, to perform simulations of large shallow crustal rupture scenario earthquakes using the 1994 M6.7 Northridge, California earthquake slip distribution. The …

Approaches To Model Non-Uniqueness And Site Complexity For Non-Invasive Shear-Wave Depth Profiling, Christopher Boucher

Electronic Thesis and Dissertation Repository

Shear-wave velocity (VS) depth profiling and associated seismic site classifications were performed at 15 sites across Metro Vancouver, British Columbia using passive seismic and surface wave methods. Inversion model parameters are constrained at each site using nearby geodata in combination with developing regression models of shear-wave velocity with depth for three primary stratigraphic units. Statistical methods such as a Bayesian Information Criterion are applied post-inversion to evaluate models between and within varying parameterizations. Data evaluation metrics, including the use of microtremor horizontal-to-vertical spectral ratios (MHVSRs), are applied to identify two common deviations from the simple case of normally dispersive laterally …

Geomechanical Modeling Of A Fault During Fluid Injection, Charles Kw Hulls

Electronic Thesis and Dissertation Repository

The injection of fluid into rock masses as a part of industrial processes, such as hydraulic fracturing, can lead to an increase in seismic activity. The movement of the injected fluid and resulting stresses can be simulated and analyzed. One aspect of this analysis is the predicted rate of seismic activity, obtained via the Dietrich rate-and-state law and the Coulomb Failure Stress. This work produces simulations for two fracturing scenarios in the Duvernay Shale region. Model parameters, such as layer permeability and timing of fault slip, are varied to determine their impact on the model results. The simulated results show …

Examining Κ, The High Frequency Spectral Decay Parameter, In Eastern Canada, Samantha M. Palmer

Electronic Thesis and Dissertation Repository

This thesis examines the ground motion modeling parameter kappa (κ) in the stable continental region of eastern Canada. Kappa characterizes the decay of spectral amplitudes at high frequencies due to near-surface material de-amplification and is important in seismic hazard assessments. Kappa has significant economic and seismic safety implications for critical infrastructure such as nuclear power plants and dams.

To examine kappa in eastern Canada, a database of ground motions to analyze near-source ground motion characteristics is developed. The database consists of ground motion records from 3357 earthquakes of moment magnitude (M) ≥1.5 recorded within 150 km of 25 …

Testing Aftershock Forecasts Using Bayesian Methods, Elisa Dong

Electronic Thesis and Dissertation Repository

The presence of strong aftershocks can increase the seismic hazard following a large earthquake and should be considered for operational earthquake forecasting and risk management. Aftershock forecasts are generated from seismicity models during the evolution of the aftershock sequence. This work compares quantitative test results of the forecasting abilities for three competing aftershock rate models - the modified Omori law, the Epidemic Type Aftershock Sequence model, and the compound Omori law - to identify the best performing model for forecasting the largest aftershock during the early aftershock sequence. Forecasts of large aftershock probabilities are generated by either the Extreme Value …

Surface Morphology And Subsurface Ice Content Relationships In Arcadia Planitia, Mars And The Canadian High Arctic, Shannon M. Hibbard

Electronic Thesis and Dissertation Repository

As NASA and SpaceX prepare for future human missions to Mars as part of an In-situ Resource Utilization (ISRU) Space Act Agreement (SAA), we need more detailed characterization of ice at proposed landing sites to constrain ice accessibility, landing safety, and scientific value. Obtaining near-surface in situ water-ice can be used for rocket fuel and life support needs which would significantly reduce the mass needed for transport to and from Mars. Arcadia Planitia is the lowest-lying region in the northern hemisphere of Mars where abundant evidence exists for an ice-rich subsurface. Shallow Radar observations indicate a decameters-thick layer of water-ice …

Stochastic Source Modelling And Tsunami Analysis Of The 2012 Mw 7.8 Haida Gwaii Earthquake, Karina Martinez Alcala

Electronic Thesis and Dissertation Repository

The Mw 7.8 2012 Haida Gwaii Earthquake triggered a tsunami that highlighted the importance of tsunami hazard assessment on Canada’s Pacific coast. Stochastic source modelling serves as a valuable method to assess future tsunami hazard and has not been performed for this region. The source models characterize the uncertainty of earthquake ruptures by considering variability in fault geometry and slip heterogeneity, which, in turn, allows the consideration of a wide range of tsunami scenarios in the Haida Gwaii region. The model predictions are constrained by observational data and past source inversion studies. One hundred twenty-eight stochastic tsunami scenarios are generated …

Seismic Imaging In Crystalline Terrains Of The Superior Province, Canada, Brian Villamizar

Electronic Thesis and Dissertation Repository

The imaging of structures in sedimentary basins has typically been carried out using conventional seismic reflection techniques. In complex geological architectures, such as those within the Superior Province in Canada, conventional seismic imaging yields suboptimal results due to factors stemming from complex energy scattering and crooked seismic geometries. Full-waveform inversion (FWI) is a nonlinear inverse technique capable of retrieving quantitative images of velocity structures. Judicious data preconditioning, and multiscale inversion strategies allow FWI to effectively estimate velocity variations in the first few kilometers of the subsurface. Non-conventional seismic reflection processing, based on azimuthal binning and enhanced migration velocity models, improves …

A Periglacial Landsystem Analysis In The Canadian High Arctic: A Tool For Planetary Geomorphology, Chimira Nicole Andres

Electronic Thesis and Dissertation Repository

Permafrost underlies 50% of Canada’s terrain and underlies 24% of the Earth’s total land area. It is a major driving force in the generation and evolution of patterned ground landforms such as polygons, stone circles, mud boils, and stripes, etc. that are seen on both the surface of the Earth and Mars, specifically in periglacial domains. The distribution of subsurface ice in these landforms (i.e. polygonal terrain) on Earth is a key constraint on past climate and process-form relationships in high arctic and periglacial regions. These landforms also have the potential of storing ice in the subsurface meaning that the …

Earthquake Site Characterization Of Rock Sites In Eastern Canada And Stiff Ground Sites In Vancouver, British Columbia, Sameer Ladak

Electronic Thesis and Dissertation Repository

Site characterization is a crucial component in assessing seismic hazard, typically involving in situ shear-wave velocity (V_S) depth profiling, and measurement of site amplification including site period. These methods are ideal for soil sites and less reliable in more complex geologic settings including rock sites. A multi-method approach to earthquake site characterization is tested at 25 seismograph stations across Eastern Canada. It is typically assumed these stations are installed on hard rock. We seek to identify which site characterization methods are most suitable at rock sites as well as to confirm the hard rock assumption. Active-source refraction and …

Source Parameters Of Induced Seismicity In North America, Joanna M. Holmgren

Electronic Thesis and Dissertation Repository

Source parameters of earthquakes play a key role in the understanding of earthquake behavior and modelling of seismic hazard. They describe the size of earthquakes, including how much energy is generated during the rupture, and how the ground motion is distributed over different frequency bands and azimuths. The last decade’s increase in induced seismicity caused by oil and gas production has led to an interest in understanding the underlying earthquake processes and how they can be modelled. This thesis is divided into three studies, each examining source parameters of induced earthquakes in North America.

In the first study, I show …

Numerical Simulations Of Complex Crater Formation In Layered And Mixed Targets, Ryan Hopkins

Electronic Thesis and Dissertation Repository

Numerical simulations of hypervelocity impact events provide a unique method of analyzing the mechanics that govern impact crater formation. This thesis describes modifications that were made to the impact Simplified Arbitrary Lagrangian Eulerian (iSALE) shock-physics code in order to more accurately simulate meteorite impacts into layered target sequences and details several applications that were investigated using this improved strength model.

Meteorite impacts occur frequently in layered targets but resolving thin layers in the target sequence is computationally expensive and therefore not often considered in numerical simulations. To address this limitation iSALE was modified to include an anisotropic yield criterion and …

Statistical Modeling And Characterization Of Induced Seismicity Within The Western Canada Sedimentary Basin, Sid Kothari

Electronic Thesis and Dissertation Repository

In western Canada, there has been an increase in seismic activity linked to anthropogenic energy-related operations including conventional hydrocarbon production, wastewater fluid injection and more recently hydraulic fracturing (HF). Statistical modeling and characterization of the space, time and magnitude distributions of the seismicity clusters is vital for a better understanding of induced earthquake processes and development of predictive models. In this work, a statistical analysis of the seismicity in the Western Canada Sedimentary Basin was performed across past and present time periods by utilizing a compiled earthquake catalogue for Alberta and eastern British Columbia. Specifically, the frequency-magnitude statistics were analyzed …

The Effect Of Stiffness Anisotropy Of A Glacial Clay On The Behaviour Of A Shallow Wind Turbine Foundation, Jesús A. González-Hurtado

Electronic Thesis and Dissertation Repository

Shallow wind turbine foundations are designed based on investigations of the ultimate, serviceability and fatigue limit states. The serviceability limit state design approaches in particular are based on simple isotropic elastic half-space analyses that ignore coupling between loading directions, and soil non-linearity and elastic anisotropy. Many of the wind farms in Ontario are constructed around the Great Lakes basin and a number of these areas are characterized as stiff clayey glacial tills. It is recognized that many of these glacial materials exhibit some degree of strength, stiffness and fabric anisotropy. This research aimed to characterize the anisotropic geotechnical properties of …

Considering A Seismically Active Leech River Valley Fault Zone In Southwestern British Columbia, Jacob J. Kukovica

Electronic Thesis and Dissertation Repository

The transpressional reverse Leech River fault (LRF) extends across the southern tip of Vancouver Island and beneath the city of Victoria, British Columbia, Canada. New paleoseismic studies suggest at least three surface-rupturing earthquakes have exceeded a moment magnitude (M) of 6 within a proposed Leech River Valley Fault Zone (LRVFZ) within the last 9,000 years. We examine the impact of an active LRVFZ to predicted earthquake ground motions for Victoria. In a probabilistic formulation considering the likelihood of all earthquake sources, LRVFZ earthquakes will contribute the most to high-frequency ground motions (≥ 10 Hz) in Victoria. The Canadian …

Electrical Resistivity Of Nickel, Iron And Iron-Silicon Alloy Melts At High Pressure With Implications For The Thermal Conductivity Of The Earth’S Core, Reynold E. Silber

Electronic Thesis and Dissertation Repository

The Earth’s liquid outer core (OC) is composed of Fe alloyed with up to 10% Ni and a small fraction of light elements. However, the effect of light elements such as Si on the transport properties of liquid Fe-alloy in Earth’s OC is not clear. Thermal conductivity (κ) and related electrical resistivity (ρ) are the least constrained parameters in OC. Therefore, the characterization of transport properties of Ni, Fe and Fe-Si at high pressure has important geophysical implications for the Earth’s core. The ρ of solid and liquid Ni, Fe and Fe 4%Si was measured at …

Robust Earthquake Site Classification Assessment At Ontario Bridge Sites., Alex Bilson Darko

Electronic Thesis and Dissertation Repository

Canadian seismic design guidelines classify subsurface ground conditions based on the average shear-wave velocity (V_S) of the upper 30 meters (V_S30). We seek to optimize a robust earthquake site classification procedure for Ontario bridge sites, assessed primarily from blind comparison of non-invasive V_S depth profiling techniques. Non-invasive seismic testing is performed at 10 bridge sites in southern Ontario co-located with invasive penetration and/or borehole V_S measurements. Non-invasive surface wave dispersion and site amplification functions are jointly inverted to retrieve V_S profiles at each site. A general correlation between corrected V_S and cone …

Empirical Characterization Of Induced Seismicity In Alberta And Oklahoma, Mark Novakovic

Electronic Thesis and Dissertation Repository

This thesis characterizes ground motions from induced seismic events in Alberta and Oklahoma, following an overall methodology that uses ground-motion recordings to calibrate the parameters of a seismological model. This body of work is carried out in three related studies.

In the first study, we perform a preliminary evaluation of ground motions in Alberta using thousands of observations of natural, induced and blast events of magnitude 1 to 4, recorded on a newly-deployed regional seismograph array. We evaluate the applicability of a moment magnitude (M) estimation algorithm for the events and compare the observed ground motions with expectations …

Impact Craters On Titan: Finalizing Titan's Crater Population, Joshua E. Hedgepeth

Electronic Thesis and Dissertation Repository

Titan is one of the most dynamic moons in the solar system. It is smaller than Earth and much colder, yet Titan is eerily similar to Earth, with rivers, rain, and seas, as well as sand seas that wrap around the equator. However, the rivers are made of hydrocarbons rather than water and the sand made of organics rather rock. We can use Titan’s impact craters to study how these processes modify the surface by comparing the craters depths, diameters and rim heights of Titan’s craters with fresh craters. Therefore, we have used the complete data set from NASA’s Cassini …

Geomechanical Modelling Of Induced Seismicity, Bodi Zhao

Electronic Thesis and Dissertation Repository

In recent years, there has been a dramatic increase in seismicity (earthquakes) due to anthropogenic activities related to the unconventional oil and gas exploration in the Western Canada Sedimentary Basin (WCSB) and the central U.S. There are compelling evidences that hydraulic fracturing and wastewater injection operations in those areas play a key role in induced seismicity. To better understand the physical mechanisms involved, this thesis aims to explore the mechanisms responsible for occurrence of induced earthquakes: mainshock-aftershock triggering mechanism and poroelastic response. In the first approach, the obtained results indicate the relationship between the Coulomb stress changes after 4 moderate …

Mitigating Non-Linearity In Full Waveform Inversion Using Scaled-Sobolev Norms, Mohammad Akbar Hosain Zuberi

Electronic Thesis and Dissertation Repository

Seismic full waveform inversion (FWI) is a non-linear problem. The Born approximation provides a way to linearize FWI and obtain a gradient in a computationally efficient manner. However, this linearization is only valid if the background velocity is sufficiently known, which often is not possible in practice. There have been various attempts at solving problems associated with the non-linearity of FWI by separating the problems of background and scatterer inversion. Most of the methods, however either depend on the availability of low frequencies and large offsets in the data, or separate the spatial scales completely, which removes the scattered information …

Investigating The Mechanism Of Deep-Focus Earthquakes Via In-Situ Acoustic Emission Experiments On Fe2sio4 At High Temperature And Pressure, Timothy Officer

Electronic Thesis and Dissertation Repository

In subduction zones, earthquakes are thought to be associated with faulting that arises from phase transformations. In order to test the viability of this mechanism experimentally, it was necessary to make microseismic measurements while the mineral under investigation was subjected to the pressure and temperature (P,T) conditions corresponding to their environment at depth. A system has been developed capable of making in situ acoustic emission (AE) measurements on samples under P,T conditions representative of the upper mantle and transition zone. Experiments were performed in a 3000-ton multi-anvil press using an 18/11 octahedral cell with 6 piezoelectric transducers mounted on the …

Time Series Analysis Of Surface Deformation Associated With Fluid Injection And Induced Seismicity In Timpson, Texas Using Dinsar Methods, Simon Thorpe

Electronic Thesis and Dissertation Repository

In recent years, a rise in unconventional oil and gas production in North America has been linked to an increase in seismicity rate in these regions (Ellsworth, 2013). As fluid is pumped into deep formations, the state of stress within the subsurface changes, potentially reactivating pre-existing faults and/or causing subsidence or uplift of the surface. Therefore, hydraulic fracturing and/or fluid disposal injection can significantly increase the seismic hazard to communities and structures surrounding the injection sites (Barnhart et al., 2014). On 17th May 2012 an Mw4.8 earthquake occurred near Timpson, TX and has been linked with wastewater injection operations in …

Geophysical Study Of Complex Meteorite Impact Structures, William Zylberman

Electronic Thesis and Dissertation Repository

Hypervelocity impact craters are the most abundant morphologic features on rocky planetary bodies of the Solar System, except on Earth where they have mostly been erased by plate tectonics, erosion, or are buried under sediments. The internal structure of complex impact craters can only be studied on Earth by using ground-truth geophysical and geological studies. Such approaches - combined with modeling - can reveal how impact cratering, target geological composition, erosion and other post-impact processes can lead to the observed geophysical anomalies, which could also be detected by remote geophysical data on other planetary surfaces. In this work, a multidisciplinary …

New Gps Time Series Analysis And A Simplified Model To Compute An Accurate Seasonal Amplitude Of Tropospheric Delay, Hadis Samadi Alinia

Electronic Thesis and Dissertation Repository

Horizontal and vertical deformation of the Earth’s crust is due to a variety of different geophysical processes that take place on various spatiotemporal scales. The quality of the observations from spaced-based geodesy instruments such as Global Positioning System (GPS) and differential interferometric synthetic aperture radar (DInSAR) data for monitoring these deformations are dependent on numerous error sources. Therefore, accurately identifying and eliminating the dominant sources of the error, such as troposphere error in GPS signals, is fundamental to obtain high quality, sub-centimeter accuracy levels in positioning results.

In this work, I present the results of double-differenced processing of five years …

A Comparison Of Ground Motion Characteristics From Induced Seismic Events In Alberta With Those In Oklahoma, Krista M. Kaski

Electronic Thesis and Dissertation Repository

Ground motions from potentially-induced seismic events in Alberta of magnitude (M) > 3, recorded within 100 km, are empirically characterized in terms of their response spectral shapes and amplitudes. Ground motions are compared statistically to those from induced events in Oklahoma, as well as to three benchmark ground motion prediction equations (GMPEs), derived from natural events. Discrepancies between Alberta and Oklahoma events appear to be magnitude-dependent, and distance-independent. For events greater than M~4, the ground motions appear equivalent in the two regions. High-frequency motions from M< 3.5 events in Alberta are weaker than those of natural events, even those at shallow focal depths. For larger magnitudes, the residuals between the Alberta motions and benchmark GMPEs (Yenier and Atkinson, 2015; Atkinson, 2015; Abrahamson et al., 2014) suggest that observations are in reasonable accord with the models. These results provide a further understanding of ground motions from induced events in Alberta.

Assessment Of Earthquake Site Amplification And Application Of Passive Seismic Methods For Improved Site Classification In The Greater Vancouver Region, British Columbia, Frederick Andrew Jackson

Electronic Thesis and Dissertation Repository

There is renewed interest to improve seismic microzonation mapping in Greater Vancouver, British Columbia (BC). We investigate local geology as the cause of observed variable ground shaking from the 2015 M 4.7 Vancouver Island earthquake. We observe high amplification at 4-6 Hz on thick sediment and the northern edge of the Fraser River delta, and disparities with current regional seismic microzonation mapping. Site amplification and shear-wave velocity (V_S) are assessed from the first borehole earthquake recordings in BC. We also perform ambient vibration analyses at 13 new locations in southwest BC to highlight suitability of passive seismic methods …