Physical Sciences and Mathematics Commons^™

The Role Of Heterogeneity In Earthquake Rupture Dynamics: Insights From Friction Experiments On A 1-Meter Laboratory Fault, Alejandro Aguilar

All Graduate Theses and Dissertations, Fall 2023 to Present

Tectonic faults are made of many kinds of rocks and minerals, creating natural weak and strong zones along faults where earthquakes occur. These differences can affect how faults move, including whether slip occurs slowly and quietly or suddenly and destructively during an earthquake. However, it is not fully understood how these variations influence when earthquakes start, how fast they spread, and whether they stop or grow into large ruptures. This research studies how different fault materials interact during earthquake slip. Using a large laboratory machine that simulates fault movement under realistic conditions, we recreate earthquake processes and closely measure how …

Evolution Of Propagator Wakes On The Kolbeinsey Ridge From An Integrated Geophysical Perspective, Ethan Stowell

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

Oceanic lithosphere is formed following the extension and rifting of a continent, with new material generated at mid-ocean ridges. While ridges generally spread in the direction of extension, individual spreading centers are offset by perpendicular transform faults that break the ridges into individual segments. Ridge propagation, in which one ridge segment grows at the expense of another’s shortening, has been identified in global investigations as a poorly understood component of axial reorganization. This process leaves propagator wake structures composed of faults and pseudofaults visible as lows in Earth’s gravitational field, and transferred lithosphere with a distorted magnetic signature. This study …

Mining Legacy And Wildfires: Interfacial Reactions Affecting Metal Mobility, Eresay Alcantar-Velasquez

Earth and Planetary Sciences ETDs

We identified water labile interfacial reactions between laboratory burned pinewood ash and mine waste solids that influence metal mobilization. The Upper Gallinas Creek Watershed in New Mexico is affected by wildfires and mining legacy. Pinewood and mine waste sediments were sampled from the area, and the pinewood was burned at 350°C to simulate medium burn intensity ignition. Rapid desorption and gradual dissolution of Mn and Fe was detected by ICP-MS as pH decreased over time. After reacting 18 MΩ ultra-pure water with a mixture of pinewood ash and mine waste sediments Fe (143%) and Mn (89.2%) concentrations increased over time. …

Mapping Along-Strike Changes In Shallow Subduction Zone Geometry At The Alaska Subduction Zone Using Seismic Reflection And Tectono-Geomorphic Analysis, Madelyn K. Hurd

Earth and Planetary Sciences ETDs

The Alaska subduction zone, where the oceanic Pacific plate subducts beneath the continental North American plate at a rate of 60-66 mm/yr, has hosted more >M8 earthquakes over the last century than any other subduction zone globally. The largest of these, the 1964 M9.2 Alaska earthquake, ruptured 800 km of the margin, including a high slip patch near the trench offshore Kodiak Island. The 1964 rupture area may have overlapped with the 1938 M8.3 Semidi earthquake rupture zone that lies to the west. Slip propagation near the subduction trench during large earthquakes can control tsunamigenesis, and differences in wedge geometry …

Reading The Martian Surface: Impact Crater Distributions And Geochemical Signatures In Gale Crater As Recorded By The Curiosity Rover, Megan E. Hoffman

Earth and Planetary Sciences ETDs

The Curiosity rover has been exploring Gale crater, a large impact basin near the Mars equator since 2012. This mission has greatly improved our ability to explore the surface of Mars with a suite of geologic tools and cameras and has revealed that Mars likely once resembled present-day Earth. In this dissertation, I utilize measurements and data taken by Curiosity to analyze the distribution and preservation of small impact craters at meter scales, I quantify the formation characteristics of a small impact crater cluster, and I examine the presence of barium in a geologic unit with high-Si to constrain sediment …

Hydrus Modeling Of A Sahelian Agroforestry System: An Investigation Of Local Water Balance, Nicole A. Butler

Master's Theses

Effects of drought can devastate agricultural productivity in the West African Sahel. Climate complexities, such as lower-than-average rainfall and high winds, can lead to crop failure and low yields, thereby creating food security issues. Agriculture in the Sahel is primarily rainfed, and the rain is becoming increasingly unpredictable due to the changing climate. The method of intercropping groundnut (Arachis hypogea) and pearl millet (Pennisetum glaucum) with the shrub species Piliostigma reticulatum can combat the effects of climate change and restore degraded soil. Intercropping can increase water availability and crop yield when compared to crops grown in the absence of shrubs. …

Minerals Rock!: Improving Audience Engagement And Interest In Stem Through Enhancement Of The In-Person And Online Mineral Collection At Ursinus College, Juliette Lyons

Environment and Sustainability Summer Fellows

Museums are a vital source of educational resources for the general public. They provide information on a variety of topics and disciplines and encourage visitors to be excited about and engaged in learning something new. As we work to comprehend key topics such as climate change, it is especially important for the broader public to better understand science, including geology. While the geological collection at Ursinus, Pieces of Earth’s History, is not in a museum, implementing methods that museums use can improve the reception of the collection. Through the application of research gathered through articles, journals, books, and talking with …

Toward The Significance Of Crevasse Orientation In Low And High Crevassed Regions On The Kennicott Glacier, Alaska, Usa, Claire A. Sturm

DePaul Discoveries

Supraglacial landforms serve as potential indicators of underlying bedrock morphology and glacier dynamics. The distribution and morphology of crevasses are closely associated with stress fields and ice-flow regimes, representing processes of stable glaciers, in contrast to their reduced occurrence in stagnant or receding ice masses. The orientation and density of crevasses influence a glacier’s ability to absorb solar energy, as they facilitate movement of meltwater down to subglacial rivers. Beyond the meltwater acting as a lubricant for basal sliding, the slope of the bedrock further impacts the local velocity and ice deformation of a glacier. The study of ice-fracturing mechanics …

Elemental Analysis Of Upper Devonian To Lower Mississippian Organic-Rich Mudstone Cores From Kentucky By Portable X-Ray Fluorescence (Pxrf), Alex M. Washburn

KGS Research Data Set

This dataset contains high-density portable X-ray fluorescence (pXRF) elemental analyses of 1,867 m (6,125 ft) of Upper Devonian to Lower Mississippian organic-rich mudstone cores from Kentucky. Analyses were collected from cores across the Illinois Basin, Cincinnati Arch, and Appalachian Basin to support regional evaluation of elemental variability, chemostratigraphy, and redox-sensitive trace-metal enrichment in Devonian–Mississippian mudstone successions. All measurements were conducted using a Bruker Tracer 5 pXRF analyzer with the factory “Mudrock Air” calibration, using analytical settings optimized for both low-atomic-number elements and transition metals/redox-sensitive trace elements. Reference materials SARM-41 and SGR-1 were analyzed throughout the analytical sequence to monitor instrument …

Glacier Elevation Difference Data For The Conterminous U.S., Andrew G. Fountain, Bryce Allen Glenn, Christopher Mcneil, Brian Menounos

Geology Faculty Datasets

Historic and recent elevation data for the glaciers in the conterminous US were differenced to estimate glacier mass and volume change.

Historic glacier elevations were obtained from the USGS National Elevation Dataset (https://doi.org/10.15760/geology-data.04), a digitized product from the USGS 1:24,000 paper topographic maps that included the glacier extent (Gesch, 2007). Recent glacier elevations were derived from aerial lidar and from satellite radar. The lidar data were largely obtained from the USGS 3D Elevation Program (Stoker and Miller, 2022; US Geological Survey, 2024), and filtered by acquisition date using only those data collected between mid-summer and early autumn. The …

Hydrogeochemical Characterization Of Groundwater In Fractured Crystalline Basement Aquifers In Dodoma, Central Tanzania: Implications On Water Quality For Domestic And Irrigation Applications, George J. Ishabairu, Simon R. Melchioly, Charles H. Kasanzu, Gabriel D. Mulibo

Tanzania Journal of Science

Assessment of groundwater hydrogeochemistry characteristics of aquifers plays a vital role in establishing water quality status and its suitability for human and industrial use. The main objective of this research was to carry out hydrogeochemical characterization of groundwater and assess its impacts on water quality and spatial variability of groundwater geochemistry in Dodoma, Tanzania. The methods used include groundwater sampling, laboratory analysis to determine physico- chemical parameters and data processing to classify the groundwater hydrochemical facies. The results show that the average value for pH is 7.2, for electrical conductivity (EC) is 1108 µS/cm and for total dissolved solids (TDS) …

An Overlooked Terrestrial Archive: Freshwater Cements And Hydroclimate Signals In Quaternary Glaciogenic Deposits, Owen F. Mccaffrey, Ian Z. Winkelstern, Tara A. Kneeshaw, Melinda C. Higley

University Faculty Publications and Creative Works

Quaternary glaciogenic deposits, which serve as vital groundwater aquifers, are often partially cemented with carbonate minerals, but the timing of emplacement of these cements and their geochemical conditions of formation remain understudied. Here, we integrated petrography, δ¹⁸O, Mg/Ca, and clumped isotope (Δ₄₇) data from two calcitecemented outcrops in western Michigan (USA) to investigate the origin of glacial sediment cements. The two sites have contrasting topographic and textural settings reflecting distinct formation conditions. The elevated Wabasis Lake deposit records sequential phreatic-to-vadose cementation, while the Cherry Valley Sands site, very close to the modern water table, shows a …

Interseismic Creep Along The Enriquillo–Plantain Garden Fault, Haiti, Estimated From Insar, Rishabh Dutta, Jeremy L. Maurer, Yi Chieh Lee

Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works

The Enriquillo–Plantain Garden fault zone (EPGFZ) is a major left-lateral strike-slip fault in southern Haiti hosting several recent destructive earthquakes, including the 2021 MW 7.1 Nippes event with primary thrust-slip. To investigate how strain is accommodated in the vicinity of the 2021 event, we analyzed Sentinel-1 interferometric synthetic aperture radar (InSAR) data from 2017 to 2021 using a PS + DS (persistent + distributed scatterers) InSAR time-series approach to overcome decorrelation in this highly vegetated region. We reveal interseismic creep along the EPGF and adjacent Grand'Anse–Sud border faults, with pure strike-slip mechanism and rates up to 9 mm/yr. We suggest …

Exploring Paleoproterozoic Marine Redox States In A Young Banded Iron Formation From The Needle Mountains, Jaya Sharma

Earth Sciences Undergraduate Senior Theses

Banded iron formations (BIF) are redox-dependent chemical sedimentary rocks that have served as proxies for marine and atmospheric oxygen and iron conditions throughout Earth's history. While abundant in the Archean and early Proterozoic, the widespread deposition of BIFs declined following the Great Oxidation Event, as oxygenated surface waters prevented the accumulation of ferrous iron. However, the Needle Mountains, located in southwestern Colorado, house an anomalously young BIF deposited between 1786±10 Ma - 1801±6 Ma given existing geochronology. Here, we use rare earth element (REE) systematics, bulk chemistry, and petrographic analysis to determine the depositional conditions under which this BIF was …

Assessing Spatial Distribution Of Plausible Earthquake-Triggered Landslides Relative To Ca. 1000 Ybp Earthquake On The Gales Creek Fault, Jacqueline Rheingans

University Honors Theses

Modern coseismic landslides cluster near the surface trace of the fault that ruptured, suggesting that clustering of paleolandslides may record information about paleoearthquakes. This study documents the pattern of prehistoric landslides near the Gales Creek Fault (GCF), northwest Oregon, to assess whether it reflects an independently known paleoearthquake. The GCF is located northwest of Portland through the Cascadia fore-arc basin where landslides are often triggered by intense rainfall during the wet season or potentially by seismic shaking on the megathrust or on crustal faults. In order to understand how a seismic event on the GCF will impact landslide distribution I …

Tectonics: Supporting Information For Deformation Rates And Patterns Of The Emerging Banda Ranges Revealed By Uplifted Coral Terraces In Timor-Leste, Ron Harris, Nicole Cox, Megan Flexhaug, Dorothy Merritts, Chua-Chou Shen, Frederico Santos

ScholarsArchive Data

The supplementary information provided consist primarily of figures detailing coral terrace profiles and terrace inner margin elevation to MIS highstand correlations.

• a general overview of the kind of data files;
• a general description of processing steps used;
• any known imperfections or anomalies in the data.

Investigating The Distribution And Origin Of Pitted Mounds On Mars Using Machine Learning-Based Mapping And Integrated Geological Analysis: Application To Isidis Planitia, Precious Batubo

Doctoral Dissertations

Pitted mounds are widespread landforms across the northern plains of Mars, yet their origin remains uncertain. These features have been interpreted as possible expressions of subsurface fluid activity, including sedimentary volcanism, magmatic processes, or other fluid-assisted mechanisms. Determining their distribution, morphology, and geology is therefore important for understanding the evolution of subsurface hydrological processes and the planet’s potential for habitability. However, the large spatial extent of mound-bearing terrains makes comprehensive manual mapping impractical. This dissertation presents an automated approach to mound detection using Faster Region-Based Convolutional Neural Network (Faster R-CNN) from high-resolution Context Camera (CTX) images including morphometric and mineralogical …

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