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Articles 271 - 300 of 2451
Full-Text Articles in Geophysics and Seismology
Causes, Responses, And Implications Of Anthropogenic Versus Natural Flow Intermittence In River Networks, Kendra E. Kaiser
Causes, Responses, And Implications Of Anthropogenic Versus Natural Flow Intermittence In River Networks, Kendra E. Kaiser
Geosciences Faculty Publications and Presentations
Rivers that do not flow year-round are the predominant type of running waters on Earth. Despite a burgeoning literature on natural flow intermittence (NFI), knowledge about the hydrological causes and ecological effects of human-induced, anthropogenic flow intermittence (AFI) remains limited. NFI and AFI could generate contrasting hydrological and biological responses in rivers because of distinct underlying causes of drying and evolutionary adaptations of their biota. We first review the causes of AFI and show how different anthropogenic drivers alter the timing, frequency and duration of drying, compared with NFI. Second, we evaluate the possible differences in biodiversity responses, ecological functions, …
Carbon Capture, Utilization, And Storage, University Of North Dakota. Energy And Environmental Research Center
Carbon Capture, Utilization, And Storage, University Of North Dakota. Energy And Environmental Research Center
EERC Brochures and Fact Sheets
Fact sheet about carbon capture, utilization, and storage (CCUS) and the Energy & Environmental Research Center’s CCUS capabilities. Includes information on the Plains CO2 Reduction (PCOR) Partnership initiative, Brine Extraction and Storage Test (BEST), Carbon Storage Assurance Facility Enterprise (CarbonSAFE), Red Trail Energy Carbon Capture and Storage, a feed study at Coal Creek Station, Bell Creek and Cedar Creek anticline projects, and Partnership for CO2 Capture (PCO2C).
Closing The Modern Seismic Gap Along The Teton Fault Via Seismic Mapping Of Mass Transport Deposits In Jackson Lake, Wy, Callia Jacqueline Cortese
Closing The Modern Seismic Gap Along The Teton Fault Via Seismic Mapping Of Mass Transport Deposits In Jackson Lake, Wy, Callia Jacqueline Cortese
Theses and Dissertations--Earth and Environmental Sciences
Terrestrial paleoseismological records along the Teton fault have historically indicated two-to-three major post-Pinedale (~14 ka) earthquake events, leaving an unresolved 6-9 m offset along the modern scarp. Recent studies of Jenny Lake have augmented this record, but the triggering mechanism is still equivocal until new paleo-earthquake records are developed. The earthquake record of the Teton fault is complicated by quiescence from ~5 ka to present, demonstrating the need for additional paleoseismic investigations. Compressed, high-intensity radar pulse (CHIRP) reflection data from Jackson Lake indicates multiple potentially seismically-induced mass transport deposits (MTDs). At least six MTD Groups representing chronostratigraphic intervals were interpreted …
Discovery Of The Middle Mantle Transition Zone (Mmtz) And Its Geodynamic Significance, Yuping Wang
Discovery Of The Middle Mantle Transition Zone (Mmtz) And Its Geodynamic Significance, Yuping Wang
Theses and Dissertations--Earth and Environmental Sciences
Global mantle discontinuities and mantle transition zones are crucial to the earth’s evolution. By employing K-Means clustering, which belongs to cluster analysis in machine learning (ML), on shear velocity variation data, we generate heterogeneity percentage profiles for three different global tomographic models (Models S362WMANI+M, SEMUCB-WM1, and S40RTS). Key cluster percentage shifts, which are observed at around 400 km, 650 km, 1050 km, 1500 km, and 2700 km, suggest global mantle discontinuities at corresponding depths. All profiles also indicate a global discontinuity in the lower mantle between 2200 km and 2600 km. The middle mantle transition zone (MMTZ), bounded between 1050 …
Constraining Rock Type Controls On Geophysical Properties: Implications For Earthquake Hazard Assessment Near Ellensburg, Washington, Zachary Stevens
Constraining Rock Type Controls On Geophysical Properties: Implications For Earthquake Hazard Assessment Near Ellensburg, Washington, Zachary Stevens
All Master's Theses
High precision geophysical modeling can constrain the geometry of structures in the upper to middle crust beyond what is possible with surface data alone, which allows for a better understanding of seismic hazards. This modeling requires values of both the magnetic susceptibility and density relevant to rocks at depth; this study presents a combination of field and laboratory measurements of basement units to determine these properties. The basement rock of the Kittitas Valley is made up of a complex series of metamorphic and igneous bodies, so it was important to gather a representative suite of samples of the most volumetrically …
Paleoseismic Investigation Of Rupture On The Dead Coyote Fault In The Kittitas Valley, Washington, Garet Huddleston
Paleoseismic Investigation Of Rupture On The Dead Coyote Fault In The Kittitas Valley, Washington, Garet Huddleston
All Master's Theses
Recently discovered fault scarps along the Dead Coyote Fault (DCF) in the northern Kittitas Valley (KV) of central Washington suggests active faulting in the late Quaternary, but constraints on the timing and potential magnitude of earthquakes along the fault zone are limited. The KV lies at the northwestern edge of the Yakima Fold and Thrust Belt (YFTB), a low-strain region where individual structures are capable of producing M~7 earthquakes.
This investigation uses surficial geologic mapping and topographic analysis of the DCF scarps, ground penetrating radar transects, and paleoseismic trenching to determine the rupture history of the DCF. The trench was …
Communicating Hazard Location Through Text And Map In Earthquake Early Warnings: A Mixed Methods Study, Jeannette Sutton, Michele M. Wood, Nicholas A. Waugh, Savanah Crouch
Communicating Hazard Location Through Text And Map In Earthquake Early Warnings: A Mixed Methods Study, Jeannette Sutton, Michele M. Wood, Nicholas A. Waugh, Savanah Crouch
Emergency Preparedness, Homeland Security, and Cybersecurity Faculty Scholarship
The purpose of this research was to examine the effect of presenting hazard location in different formats on key warning message outcomes—understanding, personalizing, believing, deciding, and milling. We conducted two studies using experiment and focus group methods. In the experiment, we compared a standard ShakeAlert earthquake early warning message, which merely implied location, to three enhanced messages that communicated information about the earthquake epicenter via text, map, or a combined text-and-map format. Focus groups explored reactions to warning messages accompanied by different types of maps. Overall, the standard ShakeAlert message was associated with worse message outcomes compared to messages that …
Comprehensive Analysis Of Seismic Signals From Pacaya Volcano Using Deep Learning Event Detection, Jessica L. Devlieg
Comprehensive Analysis Of Seismic Signals From Pacaya Volcano Using Deep Learning Event Detection, Jessica L. Devlieg
Dissertations, Master's Theses and Master's Reports
Pacaya volcano located 30 km SW of Guatemala City, Guatemala, has been erupting intermittently since 1961. Monitoring of seismicity is crucial to understanding current activity levels within Pacaya. Traditional methods of picking these small earthquakes in this noisy environment are imprecise. Pacaya produces many small events that can easily blend in with the background noise. A possible solution for this problem is a machine learning program to pick first arrivals for these earthquakes. We tested a deep learning algorithm (Mousavi et al., 2020) for fast and reliable seismic signal detection within a volcanic system. Data from multiple deployments were used, …
Evaluating The Sensitivity Of Crustal Deformation To Bedrock Hydrology In A Mountain Watershed, Brett J. Oliver
Evaluating The Sensitivity Of Crustal Deformation To Bedrock Hydrology In A Mountain Watershed, Brett J. Oliver
Graduate Student Theses, Dissertations, & Professional Papers
We evaluate the sensitivity of Earth's elastic deformation to groundwater hydraulic diffusivity using coupled groundwater and elastic deformation models. Seasonal changes in terrestrial water storage cause deformation to the Earth’s crust and deeper interior that is within the observational capacity of GPS instruments. We couple finite difference groundwater simulations with geodetic forward models of crustal displacement to investigate the ability of geodetic deformation to constrain bedrock hydrologic properties. We use MODFLOW-2005 to simulate seasonal changes in groundwater flow and storage, and then use the LoadDef elastic deformation model to forward model surface displacement caused by the change in terrestrial water …
Applied Geochemistry, Geochronology And Biostratigraphy: Case Studies From The 38th Parallel Structures In Missouri And Orange Basin, Offshore Western South Africa, Marissa Kay Spencer
Applied Geochemistry, Geochronology And Biostratigraphy: Case Studies From The 38th Parallel Structures In Missouri And Orange Basin, Offshore Western South Africa, Marissa Kay Spencer
Doctoral Dissertations
"The unique alignment of the Decaturville, Crooked Creek, and Weaubleau geological structures in central Missouri, three of nine known such structures along the 38th parallel in Illinois, Missouri, and Kansas, has puzzled geoscientists for decades. Research using palynology (palynomorphs and particulate organic matter) and radiometric dating of impact spherules were used to constrain age and a relationship between these enigmatic structures and infer their paleoenvironmental conditions. Novel melting damages, unique to impact, were documented in the palynomorphs in all the three structures. Early Ordovician acritarchs with melted processes correlate with 40Ar-39Ar stepwise heating age of impact spherules …
Investigating Elastic Deformation Induced By Surface Loads On Planetary Bodies, Ashlesha Khatiwada, Hilary Martens, Donald F. Argus
Investigating Elastic Deformation Induced By Surface Loads On Planetary Bodies, Ashlesha Khatiwada, Hilary Martens, Donald F. Argus
Graduate Student Theses, Dissertations, & Professional Papers
Planetary bodies, including the Earth, deform when there is a redistribution of surface load. In this thesis, I conduct three independent projects related to surface loading, two of which investigate methods related to the modeling of surface loading and one which seeks to catalog the displacement responses of other planetary bodies to a surface load.
The first project aims to compare four methods for modeling the elastic loading response of the Earth: a homogeneous, non-gravitating, half-space method; a homogeneous, gravitating, spherical method; a homogeneous, non-gravitating spherical method; and a radially stratified gravitating spherical method. Many studies have focused on computing …
Drift Orbit Bifurcation Effects On Earth’S Radiation Belt Electrons, Jinbei Huang
Drift Orbit Bifurcation Effects On Earth’S Radiation Belt Electrons, Jinbei Huang
Graduate Theses, Dissertations, and Problem Reports (ETD)
Energetic charged particles trapped in the Earth’s radiation belt form a hazardous space environment for artificial electronic systems and astronauts. The study of Earth's radiation belt is becoming increasingly important with the development of communication technology, which plays a significant role in modern society. Earth’s radiation belt is highly dynamic, and the electron flux can drop by several orders of magnitude within a few hours which is called radiation belt dropout. The fast dropout of energetic electrons in the radiation belt, despite its significance, has not been thoroughly studied. One of the most compelling outstanding questions in Earth's radiation belt …
Historical Tsunami Observability For Izu–Bonin–Mariana Sources, Walter Szeliga, Rachelle Reisinger, Breanyn T. Macinnes
Historical Tsunami Observability For Izu–Bonin–Mariana Sources, Walter Szeliga, Rachelle Reisinger, Breanyn T. Macinnes
Geological Sciences Faculty Scholarship
The Izu–Bonin–Mariana Subduction System (IBM) is one of the longest subduction zones in the world with no instrumental history of shallow focus, great earthquakes (Mw > 8). Over the last 50 years, researchers have speculated on the reason for the absence of large magnitude, shallow seismicity on this plate interface, exploring factors from plate age to convergence rate. We approach the question from a different point of view: what if the IBM has hosted great earthquakes and no documentable evidence was left? To address the question of observability, we model expected tsunami wave heights from nine great earthquake scenarios on the …
Uncertainty Of Icesat-2 Atl06- And Atl08-Derived Snow Depths For Glacierized And Vegetated Mountain Regions, Ellyn M. Enderlin, Colten M. Elkin, Madeline Gendreau, H.P. Marshall, Shad O'Neel, Christopher Mcneil, Caitlyn Florentine, Louis Sass
Uncertainty Of Icesat-2 Atl06- And Atl08-Derived Snow Depths For Glacierized And Vegetated Mountain Regions, Ellyn M. Enderlin, Colten M. Elkin, Madeline Gendreau, H.P. Marshall, Shad O'Neel, Christopher Mcneil, Caitlyn Florentine, Louis Sass
Geosciences Faculty Publications and Presentations
Seasonal snow melt dominates the hydrologic budget across a large portion of the globe. Snow accumulation and melt vary over a broad range of spatial scales, preventing accurate extrapolation of sparse in situ observations to watershed scales. The lidar onboard the Ice, Cloud, and land Elevation, Satellite (ICESat-2) was designed for precise mapping of ice sheets and sea ice, and here we assess the feasibility of snow depth-mapping using ICESat-2 data in more complex and rugged mountain landscapes. We explore the utility of ATL08 Land and Vegetation Height and ATL06 Land Ice Height differencing from reference elevation datasets in two …
Pfas Mass Balance, Donovan Vitale
Pfas Mass Balance, Donovan Vitale
Honors Theses
First-generation, PFOS-dominant Aqueous Film Forming Foam (AFFF) concentrate of approximately 200 gallons was released to the sewer system from the Kalamazoo/Battle Creek International Airport on March 30, 2021. The AFFF release migrated to the Kalamazoo Water Reclamation Plant (KWRP), raising plant effluent above the Department of Environment, Great Lakes, and Energy (EGLE) PFOS water quality standard for a total of 46 days post-spill, although the influent concentrations exhibited sharp declines after only 7 days. By sampling influent, effluent, and biosolids daily, the only known long duration, high-frequency PFAS data set of an accidental AFFF release was generated. This study has …
Well Cave Field Report: Bracken Bat Cave And Preserve, Anthony J. Coronado, Byron T. Cox, Allison De La Houssaye, Fernando Jaime Sepulveda, Anthony Sadler, Aaron S. Yamazi
Well Cave Field Report: Bracken Bat Cave And Preserve, Anthony J. Coronado, Byron T. Cox, Allison De La Houssaye, Fernando Jaime Sepulveda, Anthony Sadler, Aaron S. Yamazi
Geophysics
Well cave is a small cave entrance that sits northeast of Bracken Bat Cave on the Bracken Bat Cave Preserve Property. The cave entrance sits above the Balcones Fault Zone, a primarily karst environment, and is mostly comprised of Edwards Limestone (EAA, 2022). The goal of this project is to successfully detect the main cave passageway, and any other potential paths that branch from it, beneath Well Cave. In order to accurately detect any passages, GPR surveying and ER testing were chosen as the main methods to do so.
(R1978) Heated Laminar Vertical Jet Of Psudoplastic Fluids-Against Gravity, Manisha Patel, M. G. Timol
(R1978) Heated Laminar Vertical Jet Of Psudoplastic Fluids-Against Gravity, Manisha Patel, M. G. Timol
Applications and Applied Mathematics: An International Journal (AAM)
A heated laminar jet of Pseudo-plastic fluid flowing vertically upwards from a long narrow slit into a region of the same fluid which is at a rest and at a uniform temperature is considered. The governing non-linear Partial differential equations (PDEs) for the defined flow problem are transformed into non-linear ordinary differential equations using the effective similarity technique-one parameter deductive group theory method. The obtained non-linear coupled Ordinary differential equations are solved and the results are presented by graphs. The effect of the Prandtl number and Grashof number on the velocity and temperature of the jet flow is discussed. Also, …
Predictions And Drivers Of Sub-Reach-Scale Annual Streamflow Permanence For The Upper Missouri River Basin: 1989–2018, Kendra E. Kaiser
Predictions And Drivers Of Sub-Reach-Scale Annual Streamflow Permanence For The Upper Missouri River Basin: 1989–2018, Kendra E. Kaiser
Geosciences Faculty Publications and Presentations
The presence of year-round surface water in streams (i.e., streamflow permanence) is an important factor for identifying aquatic habitat availability, determining the regulatory status of streams, managing land use change, allocating water resources, and designing scientific studies. However, accurate, high resolution, and dynamic prediction of streamflow permanence that accounts for year-to-year variability at a regional extent is a major gap in modeling capability. Herein, we expand and adapt the U.S. Geological Survey (USGS) PRObability of Streamflow PERmanence (PROSPER) model from its original implementation in the Pacific Northwest (PROSPERPNW) to the upper Missouri River basin (PROSPERUM), a …
The Formation Of The 8˚20’ N Seamount Chain, East Pacific Rise, Dorsey Wanless
The Formation Of The 8˚20’ N Seamount Chain, East Pacific Rise, Dorsey Wanless
Geosciences Faculty Publications and Presentations
Near-axis seamounts provide a unique setting to investigate three-dimensional mantle processes associated with the formation of new oceanic crust and lithosphere. Here, we investigate the characteristics and evolution of the 8˚20’N Seamount Chain, a lineament of seamounts that extends ~ 175 km west of the East Pacific Rise (EPR) axis, just north of the fracture zone of the Siqueiros Transform Fault. Shipboard gravity, magnetic, and bathymetric data acquired in 2016 are utilized to constrain models of seamount emplacement and evolution. Geophysical observations indicate that these seamounts formed during four distinct episodes of volcanism coinciding with changes in regional plate motion …
Statistical Analysis Of Aquifer Hydraulic Properties By A Continuous Pumping Tomography Test: Application To The Boise Hydrogeophysical Research Site, Kan Bun Cheng, Gedeon Dagan, Warren Barrash, Michael Cardiff, Avinoam Rabinovich
Statistical Analysis Of Aquifer Hydraulic Properties By A Continuous Pumping Tomography Test: Application To The Boise Hydrogeophysical Research Site, Kan Bun Cheng, Gedeon Dagan, Warren Barrash, Michael Cardiff, Avinoam Rabinovich
Geosciences Faculty Publications and Presentations
Characterizing aquifer heterogeneity is paramount for accurate flow and transport modeling. In this work, we present a new approach for statistical analysis of hydraulic properties in continuous pumping tomography tests of a phreatic aquifer. The method entails determining equivalent hydraulic conductivity (Keq), specific storage (Ss,eq), and specific yield (Sy,eq) at many locations in the field and then calculating statistical moments of the equivalent properties, assuming they are random space variables. Equivalent properties are defined as the ones pertinent to a homogeneous aquifer for which the head time …
Reprocessing Groundwater Resistivity Surveys In The Lower Mesilla Basin, New Mexico, And Texas, Leslie Bernal
Reprocessing Groundwater Resistivity Surveys In The Lower Mesilla Basin, New Mexico, And Texas, Leslie Bernal
Open Access Theses & Dissertations
The Mesilla Basin is part of the Rio Grande Basin System. Its northern boundary is definedby the Doña Ana Mountains in New Mexico and to the south by Sierra San Blas, Sierra Almirez, and Sierra La Candelaria in Mexico, where the basin changes its name to Conejos-Médanos. It supplies water for irrigation and public use to the cities of Las Cruces, NM, El Paso, TX, and Ciudad Juárez, Mexico. The southern part of the basin in the U.S. territory, known as the Lower Mesilla Basin, is bounded to the east by the Franklin Mountains, to the west by the Potrillo …
Hydrothermal Alteration Targeting And Geophysical Mineral Exploration Of Eureka And Sylvanite Mining Districts, Southwest New Mexico, Kenneth Singh
Hydrothermal Alteration Targeting And Geophysical Mineral Exploration Of Eureka And Sylvanite Mining Districts, Southwest New Mexico, Kenneth Singh
Open Access Theses & Dissertations
As part of the southwestern North American porphyry copper province, mining of natural resources in New Mexico has historically played a crucial role in economic development for over 150 years including this project area in the Little Hatchet Mountains. The northern half of the Little Hatchet Mountains lies in Grant County and includes the Eureka Mining District (EMD) whereas the southern half is in Hidalgo County and includes the Sylvanite Mining District (SMD), 38 miles southeast of Lordsburg. The EMD, a copper and silver-lead mining district from 1880-1961, had a total estimated production from the Laramide veins of 2.9 million …
Using Ground Penetrating Radar To Investigate Controls On Pedogenic Calcium Carbonate Distribution In Dryland Critical Zones, Nohemi Valenzuela Garay
Using Ground Penetrating Radar To Investigate Controls On Pedogenic Calcium Carbonate Distribution In Dryland Critical Zones, Nohemi Valenzuela Garay
Open Access Theses & Dissertations
Caliche or pedogenic calcium carbonate (CaCO3) layers are a common feature of arid soils, but the environmental controls on their distribution are not fully understood. Caliche layers are thought to play an important role in shallow subsurface water storage and movement, due to their water retention capacity and ability to impede vertical water transport (Hennessy et al., 1983). Therefore, caliche distribution and stability play a role in controlling water distribution in arid lands. However, due to its largely subsurface nature, caliche can be difficult to investigate and map without significant effort. I hypothesize that noninvasive geophysical methods, such as ground-penetrating …
Exploring The Effects Of Tree Roots On Infiltration Process, Nazife Onaral
Exploring The Effects Of Tree Roots On Infiltration Process, Nazife Onaral
Masters Theses
Effects of the root structures on soil infiltration dynamics are not clearly defined. Imaging the complex tree root structures and movement of water through the root ball is a challenging task to achieve without damaging the trees and roots by conventional methods. Commonly used methods are invasive, labor-intensive, and not easily accessible. Ground Penetrating Radar (GPR) has commonly been used to characterize soil profiles and it can be a reliable tool to map complex root structures with a novel high-resolution circular data collection technique. Electrical resistivity tomography (ERT) is another reliable geophysical method to image infiltration processes by the change …
Emplacement Of The Franklin Large Igneous Province And Initiation Of The Sturtian Snowball Earth, Mark D. Schmitz
Emplacement Of The Franklin Large Igneous Province And Initiation Of The Sturtian Snowball Earth, Mark D. Schmitz
Geosciences Faculty Publications and Presentations
During the Cryogenian (720 to 635 Ma ago) Snowball Earth glaciations, ice extended to sea level near the equator. The cause of this catastrophic failure of Earth’s thermostat has been unclear, but previous geochronology has suggested a rough coincidence of glacial onset with one of the largest magmatic episodes in the geological record, the Franklin large igneous province. U-Pb geochronology on zircon and baddeleyite from sills associated with the paleo-equatorial Franklin large igneous province in Arctic Canada record rapid emplacement between 719.86 ± 0.21 and 718.61 ± 0.30 Ma ago, 0.9 to 1.6 Ma before the onset of widespread glaciation. …
Single-Crystal Elasticity Of Earth’S Mantle Transition Zone Minerals And High Pressure-Temperature Phase Equilibrium Experiments On Martian Basalts, Wenyi Zhou
Earth and Planetary Sciences ETDs
Wadsleyite and ringwoodite are major minerals in the Earth’s Mantle Transition Zone. Global and local seismic studies have detected strong lateral variations in seismic velocity and anisotropy in the Mantle Transition Zone, reflecting temperature and possible composition variations. Interpretation of these seismic observations requires knowledge of thermoelastic properties of wadsleyite and ringwoodite with different compositions (water and Fe contents) under high pressure-temperature conditions. In this dissertation, we have measured single-crystal elastic properties of wadsleyite and ringwoodite under high pressure-temperature conditions by Brillouin spectroscopy. Based on our measurements and previous experimental results, we further model the effects of water and Fe …
Induced Seismicity In The Raton Basin And Global Variability Of The 410-Km Discontinuity, Margaret E. Glasgow
Induced Seismicity In The Raton Basin And Global Variability Of The 410-Km Discontinuity, Margaret E. Glasgow
Earth and Planetary Sciences ETDs
Natural processes like mantle convection and plate tectonics dominate Earth’s seismic structure. Recently human activities have increasingly influenced the deformation of the shallow crust. In this dissertation, passive source seismology was used to constrain seismic discontinuities in the mantle transition zone and seismogenic structures in induced earthquake settings. Using a novel sampling method and uniform processing approach, I found the 410-km discontinuity is thermally and compositionally variable. Using a machine- learning approach, I found the three main zones of seismicity in the Raton Basin consist of short faults or fault segments with variable orientations. The zone that hosted a Mw …
Dense Array Seismic Imaging Of Earth's Crust Using Active And Passive Sources, Evans Awere Onyango
Dense Array Seismic Imaging Of Earth's Crust Using Active And Passive Sources, Evans Awere Onyango
Earth and Planetary Sciences ETDs
Imaging Earth’s crust is critical to understanding processes in the near-surface that affect civilization such as the interaction of seismic waves with the near-surface to generate natural or man-made hazards or investigating how the shallow crust affects the distribution of resources. In chapter 1, I processed and analyzed active source seismic data recorded by ~1000 geophones that were acquired over the legacy HADDOCK nuclear test at the Nevada National Security Site. Using seismic reflection and refraction methods, we image the partially collapsed post-detonation structure to better understand the velocity structure in and around the HADDOCK chimney. Results from this work …
The Impact Of Contact Geometry On Sea Ice Stress And Fracture At The Scale Of Ice Floes, Michael J. May
The Impact Of Contact Geometry On Sea Ice Stress And Fracture At The Scale Of Ice Floes, Michael J. May
Dartmouth College Master’s Theses
Observations of stress and strain at the scale of ice floes are necessary to fill a gap in our understanding of sea ice mechanical behavior. Current climate and ice dynamics models represent ice mechanical properties using stress-strain relationships largely determined at laboratory-scale (<1m) or from regional-scale (10+km) deformation observations. The former scale does not include all mechanisms of deformation operating in the ice pack; the latter aggregates multiple modes of deformation into non-physical fluid analogies. The Sea Ice Dynamics Experiment (SIDEx) was run in Feb-Mar 2021 to fill this gap, observing stress and strain at the scale of sea ice failure processes. Here we present stress sensor observations. Stress gages (N=31) were deployed over a 4.5km2 area in the southern Beaufort Sea to observe in-situ stress. These data were analyzed in the context of deformation observations from satellite imagery and local laser and radar interferometers to explain the drivers of sea ice stress variations before and after fracture. Three case studies between 14 March and 24 March, during which fractures propagated through …1m)>
Hydrogeologic Investigation Of A Covered Karst Terrain, Joseph Peter Honings
Hydrogeologic Investigation Of A Covered Karst Terrain, Joseph Peter Honings
LSU Doctoral Dissertations
Increasing demand for water for agricultural use within the Dougherty Plain of the Southeastern United States has depleted surface water bodies. In karstic landscapes, such as the Dougherty Plain in southwest Georgia where the linkages between surface and ground waters are close, there is a need to understand the physical characteristics of the subsurface that allow these close linkages. Having a better understanding of the subsurface characteristics will aid numerical modeling efforts that underpin policy decisions and economic analyses. Two common features on this karstic landscape are draws and geographically isolated wetlands. Using LiDAR, aerial imagery, and ground-penetrating radar, this …