Geophysics and Seismology Commons^™

Geophysical Techniques Used For The Analysis And Prediction Of Soil Strength And Mechanical Behavior, Matthew A. Hurley

Theses and Dissertations--Civil Engineering

Determining soil properties involves extensive laboratory testing of samples at discrete timing and location. Non-destructive analysis methods, such as electrical and seismic, presents alternatives to means of gathering soil properties accompanied with increased flexibility due to spatial and temporal applications. This research examined the ability of seismic wave data to predict soil behavior such as stress-strain and pore pressures using a modified version of Duncan and Chang (1970). Friction angle predictions were also analyzed using shear wave velocity and a modified form of the Santos and Gomez-Correria (2001) equation. This research also analyzed the use of electrical data to predict …

Volcan De Fuego: A Machine Learning Approach In Understanding The Eruptive Cycles Using Precursory Tilt Signals, Kay Sivaraj

Dissertations, Master's Theses and Master's Reports

Volcan de Fuego is an active stratovolcano located in the Central Guatemalan segment of the 1100 m long Central America Volcanic Arc System (CAVAS). Fuego-Acatenango massif consists of at least four major vents of which the Fuego summit vent is the most active and the youngest member. The volcano exhibits primarily Strombolian and Vulcanian behavior along with occasional paroxysms and pyroclastic flows. Historically, Fuego has produced basaltic-andesitic rocks with more recent eruptions progressively trending towards maficity. Several studies have used short-term deployments of broadband seismometers, infrasound, and long-term remote sensing techniques to characterize the mechanism of Fuego. In our study, …

Mantle Flow Systems Associated With Slab Subduction And Absolute Plate Motion In Alaska Constrained By Shear Wave Splitting Analyses, Yuchen Yang

Doctoral Dissertations

"Alaska has long been recognized as a geologically complex region with a sharp contrast in tectonic activity between southern and northern Alaska. While the former is characterized by the subduction of the geometrically varying Pacific-Yakutat plate beneath the North American plate, the latter has a mostly stable cratonic setting. To investigate the mantle flow fields beneath Alaska and understand the influence of the subduction process on regional mantle dynamics, a total of 2790 pairs of well-defined teleseismic shear wave splitting (SWS) measurements recorded from 379 stations are obtained and analyzed. In addition, 247 pairs of SWS results from local earthquake …

Extreme Heterogeneity In Mid-Ocean Ridge Mantle Revealed In Lavas From The 8°20′N Near-Axis Seamount Chain, Molly Anderson, V. Dorsey Wanless, Michael Perfit, Ethan Conrad, Patricia Gregg, Daniel Fornari, W. Ian Ridley

Geosciences Faculty Publications and Presentations

Lavas that have erupted at near‐axis seamounts provide windows into mid‐ocean ridge mantle heterogeneity and melting systematics which are not easily observed on‐axis at fast‐spreading centers. Beneath ridges, most heterogeneity is obscured as magmas aggregate toward the ridge, where they efficiently mix and homogenize during transit and within shallow magma chambers prior to eruption. To understand the deeper magmatic processes contributing to oceanic crustal formation, we examine the compositions of lavas erupted along a chain of near‐axis seamounts and volcanic ridges perpendicular to the East Pacific Rise. We assess the chemistry of near‐ridge mantle using a ∼200 km‐long chain at …

Age And Paleoenvironmental Significance Of The Frazer Beach Member: A New Lithostratigraphic Unit Overlying The End-Permian Extinction Horizon In The Sydney Basin, Australia, James L. Crowley

Geosciences Faculty Publications and Presentations

The newly defined Frazer Beach Member of the Moon Island Beach Formation is identified widely across the Sydney Basin in both outcrop and exploration wells. This thin unit was deposited immediately after extinction of the Glossopteris flora (defining the terrestrial end-Permian extinction event). The unit rests conformably on the uppermost Permian coal seam in most places. A distinctive granule-microbreccia bed is locally represented at the base of the member. The unit otherwise consists of dark gray to black siltstone, shale, mudstone and, locally, thin lenses of fine-grained sandstone and tuff. The member represents the topmost unit of the Newcastle Coal …

Unsteady-State Contact Angle Hysteresis During Droplet Oscillation In Capillary Pores: Theoretical Model And Vof Simulation -- Supporting Information, Chao Zeng, Wen Deng, Lichun Wang

Research Data

Contact angle hysteresis (CAH) is a critical phenomenon that could significantly affect the fate of immiscible bubbles/droplets in vadose zones, nonaqueous phase liquid contaminated aquifers, and saline aquifers for CO₂ sequestration in terms of infiltration patterns and residual trapping mechanisms. When external physical impacts such as oscillatory excitation or pulse forcing are applied, it could result in pinned oscillation of droplets due to this CAH. Conventional steady-state analysis of contact angle could underestimate CAH. As the first time to take unsteady-state effect into consideration, a hydrodynamic analysis is developed in this study to address the unsteady-state CAH theoretically, and …

Analyzing Slab Holes In Subduction Zones And Their Impacts Through Numerical Simulations, Taylor M. Arrowood

Theses and Dissertations--Earth and Environmental Sciences

Subduction zones form as higher density oceanic lithosphere is forced beneath an over-riding, lower density, continental or oceanic plate; a process driven by contrasts in buoyancy throughout this system. We seek to explore subduction zones in which the subducting lithosphere is discontinuous after passing through the trench, forming a slab gap. The main research objective is to determine the effect of slab gaps on surface topography in a subduction-related orogen and asthenospheric flow into the mantle wedge using two and three-dimensional numerical mechanical models. We obtain results from 24+ models that suggest a connection between slab gaps/holes and the magnitude …

Admittance Modeling For Elastic Thickness Across The Mars Crustal Dichotomy Boundary, Aspen Davis

Theses and Dissertations--Earth and Environmental Sciences

We use a Bouguer mass-sheet approximation for spectral admittance and correlation modeling to estimate elastic thickness, crustal thickness, crustal density, and load density across the Mars crustal dichotomy boundary near the landing site of NASA’s InSight Lander. We derive and constrain the parameter ranges using RMS misfit between the observed and theoretical admittance and their error bars. Spherical cap windows of 15° (900 km) radius are used to study 15 locations in the Northern Lowlands, the Southern Highlands and near and on the boundary which suggest distinct, but not sharp, difference in lithospheric properties. Elastic thickness estimates range generally between …

Integrated Geophysical Investigation Of Near-Surface Faults - Sassafras Ridge, New Madrid Seismic Zone, Usa, Cooper Cearley

Theses and Dissertations--Earth and Environmental Sciences

The New Madrid Seismic Zone (NMSZ) is a large source of seismic hazard within the central and eastern United States. Seismogenic source parameters such as active fault location, slip rate, total displacement, and strain accommodation is poorly constrained due to the masking effect of the Mississippi Embayment sediment and agricultural practices on structures and surface expressions. Consequently, noninvasive geologic and geophysical investigation of the subsurface is needed to characterize seismogenic sources. Recent investigation of the Reelfoot Fault found that there is a strain accommodation enigma between the dextral offset at seismogenic depth versus the surface expression, Reelfoot Scarp. This strain …

The Kiwanis Site: A Multi-Method Geophysical Approach To Investigating Mound Features, Luke Burds

All Graduate Theses, Dissertations, and Other Capstone Projects

Subtle mound-like landforms can be genetically ambiguous features within a landscape. A variety of geomorphological and anthropological processes can result in these equifinal forms being difficult to interpret. Being able to reliably and noninvasively differentiate them is important for legal as well as cultural and spiritual reasons. A suite of non-invasive geophysical methods were thus used on mounds at the Kiwanis site in western Wisconsin in order to determine if culturally diagnostic indicators could be recorded in geophysical data. Genesis of these mounds is ambiguous given the presence of aeolian landforms in immediate proximity. As a control, the same geophysical …

Analysis Of Water Concentration Formed Within Deformed Synthetic Quartz Crystals, Andrew Steward

Williams Honors College, Honors Research Projects

Analyzing the strength of synthetic quartz is essential to understanding the strength of natural milky quartz, which likely controls the strength of Earth’s continental crust. Synthetic quartz is sometimes used for deformation experiments because it has a homogenous water distribution unlike natural milky quartz. The purpose of this study is to determine if annealing synthetic quartz at T = 600°C will convert the water in synthetic quartz to free water, like milky quartz, but with little water loss. Following two annealing experiments at Texas A&M University, I performed four annealing experiments to measure the water content of five synthetic quartz …

Seismotectonic Interpretation Of An Expansive Set Of Earthquake Focal Mechanisms From First Motions And Amplitude Ratios On The Yellowstone Plateau, Cristhian Salas Pazmiño

Dissertations, Master's Theses and Master's Reports

We present high-quality focal mechanisms and stress inversions based on a refined earthquake location catalog for the Yellowstone Plateau. The relocation process is based on non-linear search techniques that use three-dimensional velocity models. The original catalog contained 18,940 events between January 2010 and March 2021 and was obtained from the University of Utah Seismograph Stations. We successfully relocate 7735 earthquakes and use this information to calculate the focal mechanisms by using two approaches. First, we only consider the P-wave first motion polarities and use the HASH program. For the second approach, we include the S-wave/P-wave amplitude ratios and evaluate if …

Opening Of The Gulf Of Mexico: What We Know, What Questions Remain, And How We Might Answer Them, Irina Filina, James Austin, Tony Doré, Elizabeth Johnson, Daniel Minguez, Ian Norton, John Snedden, Robert J. Stern

Department of Earth and Atmospheric Sciences: Faculty Publications

The Gulf of Mexico is an economically important basin with more than a century-long history of hydrocarbon exploration. However, the opening history of the basin remains debated for two reasons: 1) the quality of data does not allow for reliable interpretations of crustal features beneath thick and complex overburden, and 2) most industry well and geophysical data are proprietary. The last concerted effort by industry and academia to summarize the state of knowledge regarding the Gulf of Mexico’s formation was three decades ago and resulted in publication of a major volume as part of the Decade of North American Geology …

Subsurface Architecture Of Alpine Icy Debris Fans: Integration Of Ground-Penetrating Radar And Surface Observations In Alaska And New Zealand, Robert W. Jacob, Jeffrey M. Trop, R. Craig Kochel

Faculty Journal Articles

Icy debris fans (IDFs) are extremely dynamic supraglacial landforms at the mouths of bedrock catchments between valley glaciers and icecaps. Recent studies quantified the nature, pace, and volume of mass flow processes contributing ice and sediment to IDFs by integrating field observations, drone and time-lapse imagery, and terrestrial laser scanning. New geophysical data presented herein characterize the subsurface architecture of IDFs along the McCarthy Glacier in Alaska and the Douglas, La Perouse, and Mueller Glaciers in New Zealand. Ground Penetrating Radar (GPR) profiles and soundings from field surveys during 2013–2015 provide stratigraphic evidence of the following subsurface processes important in …

Application Of 3d Seismic Signal And Geomechanical Attributes For Subsurface Fracture Characterization: A Case Study In Clearfield County, Central Pennsylvania, Iman F. Zulkapeli

Graduate Theses, Dissertations, and Problem Reports (ETD)

Hydrocarbon exploration in unconventional reservoirs is highly risky due to the nature of the reservoirs and the variability in fractures and reservoir geomechanical properties in the subsurface. The reservoir needs to be fully characterized to avoid any complication such as frac hit, wellbore failure, blowout, or even a dry hole. The Clearfield reservoir produces an exceptionally low amount of gas, compared to the neighboring region in the proximity, which has been poorly understood. This raises the question as to what causes the reservoir to have low productivity.

This study focuses on the natural fracture characterization using high-quality 3D seismic signal …

Advancement Of Full-Vector Variable-Temperature Magnetometry For Rock-Magnetic And Paleointensity Applications, Leonid Surovitskii

Dissertations, Master's Theses and Master's Reports

Data on the variation of the direction and strength of Earth’s ancient magnetic field (absolute paleointensity) provide crucial information into the mechanisms of the geodynamo and the Earth’s thermal history. However, the use of conventional methods and instrumentation for absolute paleointensity determination has been hampered by physicochemical alteration of the samples caused by multiple high-temperature cycles and long experiment durations. The reliability and efficiency of the measurement process can be improved by the measurement of the full remanent magnetization vector simultaneously with the temperature cycling of a sample. Such as approach can also substantially expand the scope of materials available …

Seismic Imaging Of The Lithospheric Structure Beneath The Upper Midwestern United States, Anthony Guajardo

Graduate Research Theses & Dissertations

The upper midwestern United States is located within the North American Craton. This area has not undergone major deformation and metamorphism since the latest rifting events in the late Precambrian to early Cambrian (0.55 to 0.53 Ga). However, this area is not completely absent of seismicity, and major structural geologic features are present, including the Wisconsin Arch, LaSalle Deformation Belt, northern part of the Illinois basin and, deeper, the presumed transition between the Yavapai and Mazatzal tectonic provinces. Since the late 1800s, approximately 30 felt earthquakes of magnitude 2 or greater have occurred within the study area. It is likely …

Hydrocarbons In The Niobrara Formation, Powder River Basin, Northeast Wyoming, From Geophysical Well Logs, Jennifer Shilo James

Graduate Research Theses & Dissertations

The Powder River Basin, located in Wyoming, is a moderate producer of hydrocarbons with production hovering around 100 million barrels of oil per year. Recently the Niobrara Formation has garnered attention for hydrocarbon exploration and production using both conventional and unconventional drilling. A quick-look method for evaluating organic content, using either existing or real time data sets gathered from geophysical well logs, provides an opportunity to rapidly, accurately, and economically assess the formation’s organic content and thus hydrocarbon bearing potential. The popular Schmoker method determines organic content by relating gamma ray intensity to formation density. It has been successfully employed …

Spatiotemporal Variations Of Upper Crustal Anisotropy Along The San Jacinto Fault Zone In Southern California And The Fairview Region In Central Oklahoma, Enyuan Jiang

Doctoral Dissertations

"To discern spatial and explore the possible existence of temporal variations of upper crustal anisotropy along an ~15 km section of the San Jacinto Fault Zone (SJFZ) in California, and in the Fairview, Oklahoma, region, we conduct systematic shear wave splitting (SWS) investigations using local S-wave data recorded by seismic stations. Strong spatial variations in crustal anisotropy are revealed by 1694 and 405 pairs of splitting parameters (including the fast polarization orientation and the splitting time), respectively. For both areas, for raypaths traveling through the fault zones, the fast orientations are parallel to the faults and may be attributed to …

Crustal And Upper Mantle Structure Beneath The Southeastern United States From Joint Inversion Of Rayleigh Wave Dispersion And Receiver Functions, Qiuyue Yang

Doctoral Dissertations

"In spite of numerous geophysical investigations have been conducted in southeastern United States, the structure and evolution of the crust and lithospheric mantle remain controversial due the thick sedimentary covers atop the crust of the coastal plains there. In this study, we use data from 186 broadband seismic stations belonging to the USArray Transportable Array to construct a 3-D shear wave velocity model for the southeastern United States for the top 180 km by a joint inversion of Rayleigh wave phase velocity dispersion and receiver functions. Our results show a clear spatial correspondence with major surficial geological features. A prominent …