Earth Sciences Commons^™

Milankovitch Paleoclimatic Signals In Upper Permian–Lower Triassic Fluvial-Lacustrine Records, Bogda Mountains, Greater Turpan-Junggar Intracontinental Rift Basin, Nw China, Wentao Zhang

Doctoral Dissertations

"The objective of this study is to understand whether Milankovitch climatic and/or tectonic processes influenced the sedimentation of the upper Permian–Lower Triassic fluvial-lacustrine cyclic deposits in Bogda Mountains, greater Turpan-Junggar intracontinental rift basin, Xinjiang Uygur Autonomous Region, NW China. This study carried out gamma analysis, gamma and astronomical tuning, and spectral analysis on the Wutonggou, Jiucaiyuan, and Shaofanggou low-order cycles of the South and Central Taodonggou, South and North Tarlong, Dalongkou, and Zhaobishan sections. Stable and positive gamma values support the assumption of facies-dependent sedimentation rates for non-marine facies. The sedimentation rates range from 0.04 to 2.43 m/kyr, and 0.21 …

Assessment Of Local Amplification Causes At Coastal Strong Motion Stations With Elevated Ground Motion Residuals From The 2024 Tewksbury, New Jersey Earthquake, Patrick Daniele

Open Access Master's Theses

Elevated ground motion amplitudes at individual stations are commonly observed in earthquake datasets, yet the physical causes of these residuals are often not explicitly identified. This study investigates two seismic monitoring stations in southeastern New York that recorded amplified motions during the 2024 Mw 4.8 Tewksbury, New Jersey earthquake. A consistent set of established geophysical methods -- including multichannel analysis of surface waves (MASW), passive ambient noise arrays (MAM), stochastic inversion, horizontal-to-vertical spectral ratio (HVSR) analysis, and directional spectral ratio techniques -- was applied to directly characterize site conditions and identify the mechanisms contributing to amplification.

Results show that elevated …

Identification And Characterization Of Tornado Seismic Signals In The Central U.S., Seth Thompson

Theses and Dissertations--Earth and Environmental Sciences

Tornadoes cause extensive property damage and endanger lives. While Doppler radar can indicate the potential for tornado development, it cannot confirm that a tornado is in contact with the ground unless a debris signature is present. While on the ground, a significant amount of a tornado’s energy may be transferred into the earth as seismic vibrations. Thus, seismometers have the potential to detect on-the-ground tornadoes. Since 1960, only five papers have published seismic recordings from tornadoes. These studies have mostly reported on seismic waves generated by tornadoes at a relatively large range, from 0.01-2.5 Hz, representing uncertainty in the dominant …

Applied Machine Learning In Mineral Prospectivity Mapping In The South Pass-Granite Mountains Of Wyoming, Carl D. York

Graduate Theses/Dissertations

The South Pass-Granite Mountains, comprised of Archean to Tertiary rocks embedded with an Archean greenstone belt in Central Wyoming, have historically been mined for gold, iron, steel, and silver. Rare earth elements have been of increasing interest in the region and thus, several datasets have become available. Knowledge driven and data driven models are used in mineral prospectivity mapping with input data including geological mapping, geochemical data, geophysical (USGS Critical Mineral magnetic and gravity data), radiometric (U, Th, K) data and multispectral remote sensing data. Mineral prospectivity has seen a rapid improvement in recent years using advancements in machine learning …

The Effects Of A Microplate On Plume-Ridge Interactions: Constraints From Comparing Easter And Juan Fernandez Microplates In The Eastern Pacific Ocean, Katherine Ames, Jennifer Georgen

OES Faculty Publications

This study investigates the nature of plume-ridge interactions near a tectonic microplate using mantle Bouguer anomaly (MBA) gravity calculations. The focus of this investigation is a comparison of the Easter and Juan Fernandez microplates, which are located in the eastern Pacific Ocean along the Pacific, Nazca, and Antarctic plate boundaries. The microplates have several similar characteristics, including general size, time of formation, and clockwise rotation within the larger bounding mid-ocean ridge systems. Unlike the Juan Fernandez microplate, however, the Easter microplate is located near a mantle plume (Easter/Salas y Gomez). Previously published geochemical data suggest that material from this plume …

Innovative Methods In Intact Rock Deformation Detection, Ali Abdullah M Alzahrani

Doctoral Dissertations

"An accurate assessment of intact rock deformation is imperative in engineering activities carried out either in or above rock masses. However, instruments used for post-peak deformation are easily debonded and cannot record the whole process of post-peak deformation required in the failure modeling of rocks. This dissertation focuses on the investigation of the performance of two non-contact measuring systems (Laser Displacement Sensor (LDS) and Inductive Proximity Sensor (IPS)) compared to the contact type instrument (conventional Strain Gauge System (SGS)) in monitoring intact rock deformations. Subsequently, an IPS was installed in a high-pressure triaxial testing system before investigating its performance in …

The Occurence Of Expansive Clay Soils In Illinois And Their Effects On Shallow Lightly Loaded Foundations, Greg James Gollaher

Masters Theses

"The damage caused to shallow foundations and slabs on grade by the shrink-swell activity of clay soils is well documented across the United States. There are local and national resources available that delineate areas that are problematic and areas that are not. These resources paint Illinois as an undemanding foundation environment. However, our experience differs from this. Our experience tells us that damage related to the shrink-swell activity of clay soils is widespread, and commonly severe causing not only cosmetic damage to structures and hard improvements but also affecting the serviceability and longevity of structures. My goal is to accurately …

The Adaptive Solution Of High-Frequency Helmholtz Equations Via Multi-Grade Deep Learning, Peiyao Zhao, Rui Wang, Tingting Wu, Yuesheng Xu

Mathematics & Statistics Faculty Publications

The Helmholtz equation is fundamental for modeling wave propagation in acoustics, electromagnetics, and geophysics; however, high-frequency regimes remain notoriously difficult due to the severe numerical “pollution effect.” We propose FD-MGDL, an adaptive framework that synergizes finite difference discretizations with Multi-Grade Deep Learning (MGDL) to efficiently resolve high-frequency wavefields. Unlike standard physics-informed neural networks (PINNs), which frequently suffer from spectral bias and heavy automatic differentiation overhead, FD-MGDL employs a progressive, grade-wise training strategy that incrementally incorporates shallow sub-networks to refine residual errors. By leveraging ReLU activations in refinement grades, the framework reformulates the highly non-convex global optimization problem into a sequence …

Empirical-Based Model Of Spatio-Temporal Errors, Godwin Naaba Ndaa

Masters Theses

This research develops an empirical model to characterize spatial-temporal InSAR errors and improve the accuracy of deformation time-series analysis. Using standardized Sentinel-1 HyP3 products and MintPy, the study quantifies how correlated noise affects velocity precision and validates the results against continuous GNSS velocities.

Residual velocities are near-Gaussian, with σ ~0.92–2.04 cm/yr and ~1 cm/yr on average. Variograms show power-law spatial structure with a non-zero nugget implicating troposphere and decorrelation while errors drop exponentially with more acquisitions; spatial uncertainty is strongly affected by unwrapping errors, coherence, and tropospheric noise, not simply troposphere.

A comparative assessment of on-demand cloud processing with other …

Report On A Gpr Survey Of The Copper Harbor Cemetery, Copper Harbor, Michigan, Grace Griffin

Dissertations, Master's Theses and Master's Reports

The Copper Harbor Cemetery in Grant Township, Michigan, is one of the oldest settler cemeteries in the Keweenaw, with the earliest burial dating back to 1853. The cemetery is also still used by the community today. However, consistent burial records have not been maintained throughout the cemetery's entire history, leading to some doubt about which areas of the cemetery can be opened for new burials and where excavation should be avoided. For this reason, Grant Township commissioned a ground penetrating radar (GPR) survey of the cemetery, primarily to locate anomalies indicating possible unmarked graves and possible buried headstones. The survey …

Bridging The Gap: Evaluating Gnss-Derived Total Water Storage As A Groundwater Monitoring Tool In The Colorado River Basin, Michelle Lee Barton

Graduate Student Theses, Dissertations, & Professional Papers

Groundwater resources in the Colorado River Basin are critically stressed yet remain under-monitored and under-regulated, creating urgent need for reliable, continuous observations at multiple spatial scales. This study evaluates the performance of the University of Montana Global Navigation Satellite Systems (GNSS) terrestrial water storage dataset as a tool for bridging groundwater monitoring gaps across the Upper and Lower Colorado River Basins between 2006 and 2024. We compare GNSS-derived total water storage and groundwater storage estimates against NASA’s Gravity Recovery and Climate Experiment (GRACE) satellite observations and in-situ groundwater well measurements at regional and sub-regional scales. We employ a Bayesian autoregressive …

Aquifer Distribution In Lukobe Ward, Morogoro Municipality, Tanzania: Mapped Resources For Sustainable Water Access, Kelvin K. Kayuni

Tanzania Journal of Science

In response to the ongoing challenges posed by the scarcity of reliable fresh-water sources in Lukobe Ward, Morogoro Municipality, Tanzania, this study applied an integrated approach that combines geospatial and geophysical datasets to identify previously undocumented aquifers. The datasets utilized include an apparent density map generated from high-resolution GGMPlus satellite gravity data, a geological map (Quarter Degree Sheet 183), a water drainage map, and a slope map created from a digital elevation model (DEM). The analysis successfully identified four unconfined, saprolitic aquifers in the study area, designated as aquifers A, B, C, and D. These aquifers span areas of 12.2 …

Fast Dispersion-Curve Inversion Using Automatic Differentiation Gradient-Based Calculation, Theodosius Marwan Irnaka, Eddy Hartantyo

Makara Journal of Science

Surface wave inversion is a crucial technique in geophysics for subsurface imaging. However, traditional methods can be computationally intensive, especially for complex models. This study introduces automatic differentiation (AD) as an efficient alternative to finite difference (FD) methods for gradient calculation in surface wave inversion. We compare AD and FD methods using three synthetic examples of varying complexity. Our results demonstrate that AD is significantly faster, with speed improvements of 3 to 12 times over FD, depending on model complexity. Moreover, AD requires up to 3 times less memory than FD. In terms of accuracy, AD provides gradient calculations that …

First-Principles Insights Into Binary Oxide Systems Under Extreme Pressure, Daniel Schacher

UNLV Theses, Dissertations, Professional Papers, and Capstones

Pressure is powerful tool by which one can manipulate the properties of materials. In this work we utilize pressure to explore binary oxide systems and characterize their structural and electronic properties. The observation of anomalous structural and electronic behavior in the rutile to CaCl2 phase transition in SnO2 led to the prediction that such behavior is inherent to all oxides experiencing such a phase transition sequence.[1] Here, the ultra-wide band gap semiconductor GeO2 is confirmed to exhibit anomalous behavior during the rutile to CaCl2 phase transition. A phase pure rutile GeO2 sample synthesized under high-pressure, high-temperature, conditions is probed using …

Towards Spatial Inversion Of Aerial Gamma-Ray Survey Data For Measurement Of Naturally Occurring Radioactivity, Daniel A. Haber

UNLV Theses, Dissertations, Professional Papers, and Capstones

Aerial gamma-ray surveying (AGRS) is used in geologic and environmental contexts to provide data on the surface spatial distribution of naturally occurring radioactive material (NORM) or other gamma-ray-emitting isotopes. The standard data reduction workflow for AGRS data involves a process whereby pointwise gamma-ray spectral data are denoised, corrected for numerous sources of background radiation and aircraft height, and are finally converted to physical values by empirical conversion factors. The reduced pointwise data are then typically spatially interpolated to form a continuous surface map.

This dissertation introduces and explores a novel spatial inversion method for reduced AGRS data that considers aircraft …

Seismological Investigations Of Magmatic Systems Using Dense Nodal Arrays, Wenkai Song

Earth and Planetary Sciences ETDs

Understanding the internal architecture of magmatic systems is crucial for volcanology, yet conventional geophysical techniques often lack the resolution to image their fine-scale structures. This dissertation leverages unique datasets from dense nodal arrays to investigate the upper crustal magmatic systems beneath Yellowstone Caldera, Valles Caldera, and Mount St. Helens. At Yellowstone, I processed vibroseis data to delineate the top of the modern magma reservoir and evaluate the thermal connection between the magmatic and the overlying hydrothermal systems. At Valles, 3D radial seismic anisotropy imaging reveals strong positive radial anisotropy within the reservoir, indicating an organized structure of horizontally sill-like melt …

Soil Characterization With Proximal Geophysics, Sophia M. Becker

Dissertations and Doctoral Documents, University of Nebraska-Lincoln, 2023–

High quality soil data is crucial for addressing numerous threats to human well-being such as water scarcity, food insecurity, and intensified natural disasters. True soil property values are determined by analyzing soil samples in a laboratory, but soil sampling is often expensive and time-consuming. Some in-field point sensors and remote sensing products are available to measure soil properties, but they have inherent limitations in measurement extent and resolution. Geophysical methods can fill the measurement scale gap between point measurements and remote sensing products, but various research questions remain open. This dissertation aims to advance understanding of geophysics-derived soil property measurements …

Modeling The Greenland-Iceland-Faroe Ridge Using Integrated Geophysical Analysis, Zachary Clowdus

Department of Earth and Atmospheric Sciences: Dissertations, Theses, and Student Research

The Greenland-Iceland-Faroe Ridge (GIFR) is an area of significant geologic interest with anomalously thick crust related to enhanced melt generation from the interaction between the Mid-Atlantic Ridge and the Iceland hotspot. To the northeast of Iceland lies the Jan Mayen Microcontinent (JMMC), which is a continental fragment separated from Greenland during the opening of the Northern Atlantic. The overall extent of the JMMC, especially its southern boundary, remains poorly constrained. The crust beneath the GIFR is believed to be primarily of oceanic affinity. However, a recent discovery of felsic lavas in Iceland led to an alternative hypothesis that implies the …

Navigating Seismic Anisotropy, With Applications To Alaska, Aakash Gupta

Geosciences

Seismic anisotropy characterizes how elastic waves travel through solid materials with different speeds, depending on the direction of the waves and the direction of particle motion of the waves. Evidence of seismic anisotropy in the Earth is widespread, from seismic waves sampling the crust, mantle and even the core, to active-source, industry-scale seismic experiments, to laboratory mea­ surements of rock samples from boreholes or at the surface. Global models of the Earth provide a highly averaged image of anisotropy. Studies based on shear wave splitting measurements from local and global earthquakes indicate that the anisotropy in the Earth is much …

Ice Surface Change And Flow Dynamics Analysis Of Sít’ Tlein (Malaspina Glacier) Through Remote Sensing, Victor Devaux-Chupin

Geosciences

Sít’ Tlein, located in southeast Alaska, is the largest piedmont glacier in the world. Periglacial lake expansion, low-lying bed, and proximity to the Pacific Ocean put its glacier lobe at risk of rapid retreat. Its disappearance would equate to removing an area of land about half the size of Rhode Island. Sít’ Tlein exhibits complex ice flow responsible for its iconic folded moraines, and for its heterogeneous ice resupply in its lobe, which occasionally surges. This lobe is gradually mantled by debris and vegetation as the ice flow fades towards its margins, protecting it from melting. This the­ sis is …

Multi-Scale Insar Investigations Of Anthropogenic And Natural Processes In The American Southwest, Emily Jo Graves

Geosciences

Arid regions in the American Southwest undergo measurable surface deformation driven by variations in subsurface fluid pressure, and other natural and anthropogenic processes. These processes range from regional scale aquifer dynamics to local oil and gas wellsite activities. This dissertation produces and then utilizes InSAR-derived average velocity fields and displacement time series to reveal and understand these multi-scale processes, their interactions, and impacts for a portion of the American Southwest. Chapter 1 discusses the climate and natural and anthropogenic processes present in our study area. In Chapter 2, we generate detailed large scale average velocity maps that reveal deformation associated …

A Kinematic, Data-Parameterized Approach To Constrain Subducted Seafloor During The Emplacement Of Shatsky Rise, Alexzandrya Katrina Shotorban

OES Theses and Dissertations

This study investigates ridge spreading rates and plate boundary geometry in interactions between large igneous provinces and mid ocean ridges, and their role in the kinematics of Shatsky Rise, an undersea volcanic plateau in the western Pacific Ocean that is roughly the size of the state of California. Shatsky Rise formed at a ridge-ridge-ridge (RRR) triple junction (TJ) (Hilde et al., 1976; Sager et al., 1988), at the intersection of the Pacific-Izanagi, Pacific-Farallon, and Izanagi-Farallon ridges, beginning at approximately 147 Ma. Investigations into Shatsky Rise’s formation are limited by the fact that two-thirds of the seafloor data has subducted with …

Advancements In Sinkhole Remediation: Field Data-Driven Sinkhole Grout Volume Prediction Model Via Machine Learning-Based Regression Analysis, Bubryur Kim, Yuvaraj Natarajan, K. R. Sri Preethaa, V. Danushkumar, Ryan Shamet, Jiannan Chen, Rui Xie, Timothy Copeland, Boo Hyun Nam, Jinwoo An

Civil Engineering Faculty Publications

Sinkhole formation poses a significant geohazard in karst regions, where unpredictable subsurface erosion often necessitates costly grouting for stabilization. Accurate estimation of grout volume remains a persistent challenge due to spatial variability, site-specific conditions, and the limitations of traditional empirical methods. This study introduces a novel machine learning-based regression model for grout volume prediction that integrates cone penetration test (CPT)-derived Sinkhole Resistance Ratio (SRR) values, spatial correlations between CPT and grouting points (GPs), and field-recorded grout volumes from six sinkhole sites in Florida. Three data transformation methods, the Proximal Allocation Method (PAM), the Equitable Distribution Method (EDM), and the Threshold-based …

Characterization Of River Discharge And Interaction With Shallow Groundwater Aquifers Along The Wabash River Using Seismological Methods, Jessica M. Cyr, Xiaotao Yang, Marty D. Frisbee

Discovery Undergraduate Interdisciplinary Research Internship

The interaction between shallow aquifers and local rivers in the West Lafayette, Indiana area remains poorly understood. While surface water levels in the Wabash River and its tributaries are monitored at several USGS stream gauges, groundwater fluctuations are less well documented. Methods using seismic recordings, sensitive to subtle ground vibrations and subsurface structure, provide an alternative to characterize groundwater levels and river discharge. This project analyzes the temporal variations of ambient noise seismic data, examining the relationship to USGS river discharge, precipitation records, and other environmental factors. We currently focus on 1) changes in maximum amplitudes and peak frequencies within …

Vulnerability Of Blue Carbon In Coastal Freshwater Ecosystems To Sea-Level Rise, Suvrajit Ghosh, Jonathan Obrist-Farner, Jeffery R. Stone, Marta Wojewodka-Przybyt, Ryan Smith, Mark Brenner, Jason H. Curtis, Susan R. H. Zimmerman, Alex Correa-Metrio, Paula Gabriela Echeverrio Galinda, Madeline J. Brosky, Liseth Perez

Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works

Coastal freshwater ecosystems are economically and ecologically important and provide multiple environmental services worldwide. They sequester carbon at rates ten times faster, and store five times more carbon per unit area than do mature tropical forests. Vulnerability of these carbon sinks to marine inundation, however, is expected to increase in response to global sea-level rise (GSLR). To better understand the implications of future GSLR, we investigated the geochemical and biological consequences of episodic Holocene marine incursions into Lake Izabal, a large coastal freshwater ecosystem on the Caribbean coast of Central America. About 8300 cal yr BP, marine incursion transformed Lake …

Integrating Satellite Observations And Modeling Approaches To Study Tectonic And Land Surface Hazards, Jeng Hann Chong

Earth and Planetary Sciences ETDs

The increasing availability of Earth observation satellites, such as SAR and optical platforms, has improved our ability to study the ground deformation processes during, after, and leading up to these natural hazards, such as earthquakes and debris flows. In this dissertation, I analyze satellite geodetic interseismic velocities across the Rakhine-Bangladesh megathrust and the influence of having realistic modeling assumptions for subduction zones to better constrain seismic hazard. I also examined changes in post-fire debris flow likelihood four years after the 2020 Lake Fire in Southern California using a suite of satellite data and field observations. Together, these studies highlight how …

Evaluation Of Towed Tem Potential For Rapid Characterization Of Levee Foundations, Kolawole Arowoogun, Katherine Grote, Jeremy Maurer

Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works

Assessing the geologic conditions of levee foundation soils is a challenging task owing to the extensive length of most levees and the heterogeneity of many alluvial deposits. Traditional investigation techniques (such as boring and cone penetrometer testing [CPT]) are expensive, invasive, and provide spatially-limited information. As a result, they are restricted to pre-identified problematic zones in the levee. To overcome these challenges, geophysical instruments capable of better spatial coverage are proposed for rapid geoelectrical characterization of levees. In this study, we presented a field-based application of the towed time-domain electromagnetic method (tTEM) system in characterizing the subsurface geology adjacent to …

Paleoseismic Evidence Of Directivity For The 1976 Mw 7.5 Motagua Earthquake, Guatemala, Jonathan Obrist-Farner, Jeremy Maurer, Derek Gibson, Trenton Mcenaney, Andreas Eckert, William F. Kenney, Jeffrey Beeson, Nigel Wattrus, Quin Stangeland, Fatima Reyes

Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works

On 4 February 1976, a Mw 7.5 earthquake along the Motagua fault, Guatemala, ruptured ∼230 km of the North American and Caribbean plate boundary. Today, the plate boundary remains poorly monitored, and the 1976 earthquake is still not fully understood. Here, we present seismic reflection profiles and radiometrically dated sediment core data from six lakes around the Motagua fault, together with reports of destruction and a quasi-dynamic rupture model, which show that the 1976 earthquake experienced strong directivity that impacted the distribution of shaking. The earthquake left behind a detailed record of event deposits (EDs) in five of the six …

Comparative Analysis Of Different Magnetic Anomaly Datasets Using Navigation Performance With Flight Test Data, Aaron P. Nielsen, Brandon M. Blakely, Patrick Duff

Faculty Publications

Magnetic Anomaly Navigation (MagNav) is a map-based method of navigation which relies on accurately obtaining the anomaly field to a high level of precision to achieve good navigation results. This requires utilizing high quality sensors, accurately modeling disturbance fields from the aircraft & other sources, and creating high-fidelity maps. Aeromagnetic survey data or marine track survey data must be processed into a product that can be used as a reference for a magnetic navigator and a variety of techniques can be utilized for this processing. The data collection for different survey types reflects choices typically made to study the underlying …

Mantle Flow And Fault Zone Related Seismic Anisotropy Revealed By A Dense Linear Broadband Array In Southeast Tibet, Jing Wu, Yinshuang Ai, Stephen S. Gao, Peixi Huang, Fansheng Kong, Deke Xu, Jianguo Song, Xinyu Gao, Mengyi Wei, Long Li, Jien Zhang, Yanbin Zhang, Yingying Zhang

Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works

Southeast Tibet, a key region for the southeastward extrusion of the Tibetan Plateau, remains debated in terms of its tectonic deformation in response to the ongoing collision between the Indian and Eurasian plates. In this study, we applied shear-wave splitting analysis of core-refracted phases recorded by a newly deployed dense seismic array and six permanent stations to delineate crustal and mantle deformation processes. The observed fast polarization directions are predominantly aligned NNW–SSE, while the splitting delay times vary across four sub-blocks. The anisotropy pattern suggests a dominantly asthenospheric origin, consistent with southeastward-directed mantle flow associated with the extrusion of the …