Physical Sciences and Mathematics Commons^™

Investigation Of Spatial And Temporal Processes Of Lake-Aquifer Interactions In The Nebraska Sand Hills, John T. Ong

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

Interaction between surface water and groundwater is an important component of the water cycle that affects the physicochemical and biological characteristics of lakes, streams, wetlands, and seacoasts. Due to the complex interaction of geologic, topographic, and hydrologic factors, flow between lakes and groundwater remains poorly understood. Evolution of conceptual models over the past 30 years describes processes of advection, dispersion, and free convection that occur in different lake flow regimes. Few detailed field studies document the validity of these conceptual models because of the difficulty of studying the subsurface and the prohibitive cost of instrumenting large areas. In the semi-arid …

Late Holocene Relationships Among Fire, Climate, And Vegetation In Rangeland Ecosystems Of Southwestern Idaho, Nathan A. Nelson, Jennifer Pierce

Geosciences Faculty Publications and Presentations

Rangelands are characterized by more arid climates than forested regions; therefore, establishing fire histories using traditional methods (e.g. fire-scars from trees or charcoal in lake sediments) is problematic. This study uses radiocarbon dating of charcoal preserved in alluvial fans and stream deposits to reconstruct a record of fire and geomorphic response in rangelands of southwestern Idaho. Samples indicate three primary periods of fire-related activity: 4400 – 4000, 2000 – 1400, and 650-400 cal yr BP. Charcoal macrofossil identification and comparison with other regional climate and fire records indicate this area has likely switched between a "fuel-limited" system (fires limited by …

An Application And Refinement Of The Karst Disturbance Index Through Evaluating Variability In Island Karst Disturbance In Puerto Rico, Brandon Lee Porter

Masters Theses & Specialist Projects

Karst environments are unique landscapes that contain important resources, including freshwater aquifers and specialized ecosystems, which are easily disturbed due to the interconnected nature of the surface and subsurface. The anthropogenic impacts on karst are deleterious to the ecosystems that are dependent on the karst environment and also to groundwater supplies. The Karst Disturbance Index (KDI) is a holistic tool used to measure anthropogenic impacts associated with karst environments, which has been applied and refined through studies performed in Florida and Italy, yet still remains untested and susceptible to modification for other areas. Application of the KDI in Arecibo, Puerto …

Stable Isotopes Of Fossil Teeth Corroborate Key General Circulation Model Predictions For The Last Glacial Maximum In North America, Matthew J. Kohn, Moriah Mckay

Geosciences Faculty Publications and Presentations

Oxygen isotope data provide a key test of general circulation models (GCMs) for the Last Glacial Maximum (LGM) in North America, which have otherwise proved difficult to validate. High δ18O pedogenic carbonates in central Wyoming have been interpreted to indicate increased summer precipitation sourced from the Gulf of Mexico. Here we show that tooth enamel δ18O of large mammals, which is strongly correlated with local water and precipitation δ18O, is lower during the LGM in Wyoming, not higher. Similar data from Texas, California, Florida and Arizona indicate higher δ18O values than in the Holocene, which is also predicted by GCMs. …

Carbon Isotope Compositions Of Terrestrial C3 Plants As Indicators Of (Paleo)Ecology And (Paleo)Climate, Matthew J. Kohn

Geosciences Faculty Publications and Presentations

A broad compilation of modern carbon isotope compositions in all C3 plant types shows a monotonic increase in δ¹³C with decreasing mean annual precipitation (MAP) that differs from previous models. Corrections for temperature, altitude, or latitude are smaller than previously estimated. As corrected for altitude, latitude, and the δ¹³C of atmospheric CO₂, these data permit refined interpretation of MAP, paleodiet, and paleoecology of ecosystems dominated by C3 plants, either prior to 7–8 million years ago (Ma), or more recently at mid- to high latitudes. Twenty-nine published paleontological studies suggest preservational or scientific bias toward …

Loring-Greenough House, North Yard Archaeogeophysics, Jamaica Plain, Massachusetts, John M. Steinberg, Christa M. Beranek, John Schoenfelder, Kathryn A. Catlin

Andrew Fiske Memorial Center for Archaeological Research Publications

An archaeogeophysical survey was carried out in May 2010 using Geonics EM-38 RT and a Malå Ground Penetrating Radar (GPR) system with a 500 MHz antenna over an 28x26 m grid immediately northeast of the Loring-Greenough house in Jamaica Plain, MA. Three major anomalies were identified. These anomalies have not been ground truthed, but they appear to be archaeological features. First, we suggest that there is builders trench just north of the house. Second, we suggest that there could be three east-west garden paths or other landscape features about 30 cm below the surface crossing the entire length of the …

Rare Earth And High Field Strength Element Partitioning Between Iron-Rich Clinopyroxenes And Felsic Liquids, Paul H. Olin, John A. Wolff

Geosciences Faculty Publications and Presentations

Rare earth elements are commonly assumed to substitute only for Ca in clinopyroxene because of the similarity of ionic radii for REE³⁺ and Ca²⁺ in 8-fold coordination. The assumption is valid for Mg-rich clinopyroxenes for which observed mineral/melt partition coefficients are readily predicted by the lattice strain model for substitution onto a single site (e.g. Wood and Blundy, 1997). We show that natural Fe-rich pyroxenes in both silica-undersaturated and -oversaturated magmatic systems deviate from this behavior. Salites (Mg# 48 to 59) in phonolites from Tenerife, ferrohedenbergites (Mg# 14.2 to 16.2) from the rhyolitic Bandelier Tuff, and ferroaugites (Mg# …

Location And Mechanism Of Very Long Period Tremor During The 2008 Eruption Of Okmok Volcano From Interstation Arrival Times, Matthew M. Haney

CGISS Publications and Presentations

We describe continuous, very long period (VLP) tremor that occurred during the 2008 eruption of Okmok Volcano, Alaska. Due to its low frequency content in band from the 0.2–0.4 Hz, the wave field of the VLP tremor is relatively free of path effects. From continuous recordings of the VLP tremor on 2 three-component broadband and 3 single-component short‐period instruments, we devise a method to locate the epicenter of the tremor based on interstation arrival times computed with cross correlation. We find the epicenter since the vertical and radial components of the VLP tremor wave field are dominated by Rayleigh waves …

Geogram 2010, David J. Keeling Editor, Wku Department Of Geography And Geology

Earth, Environmental, and Atmospheric Sciences Publications

No abstract provided.

Autonomous Fmcw Radar Survey Of Antarctic Shear Zone, Gary Koh, James H. Lever, Steven A. Arcone, Hans-Peter Marshall, Laura E. Ray

CGISS Publications and Presentations

Radar survey of the Antarctic shear zone was conducted using an ultra-wideband (2-10 GHz) frequency modulated continuous wave (FMCW) radar. The radar was mounted on a sled and pulled by a robot that was specifically designed to operate in a harsh polar environment. Our FMCW radar had good penetration through Antarctic snow and we observed snow stratigraphy to a depth of 20 m. The radar images also revealed multiple crevasses in the shear zone. Our results demonstrate that autonomous survey using high frequency radar is feasible and safe approach for detecting hidden crevasses.

2d Ground-Penetrating Radar Avo Response To A 3d Dielectric Permittivity Anomaly, John H. Bradford

CGISS Publications and Presentations

To evaluate the amplitude vs offset response of GPR to small distributions of hydrocarbon contamination, I acquired multi-offset 450 MHz GPR data in TE and TM modes over a buried rectangular tank filled with gasoline saturated sand. All dimensions of the tank were less than one wavelength at the characteristic antenna frequency. The permittivity ratio at the moist sand/gasoline sand boundary, estimated by fitting the Fresnel equations to the observed amplitudes and by Brewster's Angle analysis, differed from that obtained through migration velocity analysis by no more than 12%. 2D FDTD modeling reproduced amplitude characteristics for 3 o f 4 …

Slip Distribution Of The 1952 Kamchatka Great Earthquake Based On Near-Field Tsunami Deposits And Historical Records, Breanyn Macinnes, Robert Weiss, Joanne Bourgeois, Tatiana K. Pinegina

All Faculty Scholarship for the College of the Sciences

We explore the magnitude and slip distribution of the 1952 Kamchatka earthquake (M_W 8.8–9.0) using constraints from the 1952 Kamchatka tsunami. Our new field data provide more comprehensive coverage of the near-field tsunami than had been available to date. We examine the effects of internal slip distribution within complex earthquake ruptures on near-field tsunami runup and evaluate some of the limitations of this approach. Our approach compares tsunami-deposit distribution with simulated runup from tsunamis generated by different configurations of seafloor deformation from hypothetical earthquakes resembling that of the 1952 Kamchatka earthquake. We identify areas of high slip because different …

Ground-Penetrating-Radar Reflection Attenuation Tomography With An Adaptive Mesh, Emily A. Hinz, John H. Bradford

CGISS Publications and Presentations

Ground-penetrating radar (GPR) attenuation-difference analysis can be a useful tool for studying fluid transport in the subsurface. Surface-based reflection attenuation-difference tomography poses a number of challenges that are not faced by crosshole attenuation surveys. We create and analyze a synthetic attenuation-difference GPR data set to determine methods for processing amplitude changes and inverting for conductivity differences from reflection data sets. Instead of using a traditional grid-based inversion, we use a data-driven adaptive-meshing algorithm to alter the model space and to create amore even distribution of resolution. Adaptive meshing provides a method for improving the resolution of the model space while …

Arctic Landscapes In Transition: Responses To Thawing Permafrost, James P. Mcnamara

Geosciences Faculty Publications and Presentations

Observations indicate that over the past several decades, geomorphic processes in the Arctic have been changing or intensifying. Coastal erosion, which currently supplies most of the sediment and carbon to the Arctic Ocean [Rachold et al., 2000], may have doubled since 1955 [Mars and Houseknecht, 2007]. Further inland, expansion of channel networks [Toniolo et al., 2009] and increased river bank erosion [Costard et al., 2007] have been attributed to warming. Lakes, ponds, and wetlands appear to be more dynamic, growing in some areas, shrinking in others, and changing distribution across lowland regions …

Reproducibility Of Soil Moisture Ensembles When Representing Soil Parameter Uncertainty Using A Latin Hypercube-Based Approach With Correlation Control, Alejandro N. Flores, Dara Entekhabi, Rafael L. Bras

Geosciences Faculty Publications and Presentations

Representation of model input uncertainty is critical in ensemble‐based data assimilation. Monte Carlo sampling of model inputs produces uncertainty in the hydrologic state through the model dynamics. Small Monte Carlo ensemble sizes are desirable because of model complexity and dimensionality but potentially lead to sampling errors and correspondingly poor representation of probabilistic structure of the hydrologic state. We compare two techniques to sample soil hydraulic and thermal properties (SHTPs): (1) Latin Hypercube (LH) based sampling with correlation control and (2) random sampling from SHTP marginal distributions. A hydrology model is used to project SHTP uncertainty onto the soil moisture state …

Assessing The Potential To Detect Oil Spills In And Under Snow Using Airborne Ground-Penetrating Radar, John H. Bradford, David F. Dickens, Per Johan Brandvik

CGISS Publications and Presentations

With recent increased interest in oil and gas exploration and development in the Arctic comes increased potential for an accidental hydrocarbon release into the cryosphere, including within and at the base of snow. There is a critical need to develop effective and reliable methods for detecting such spills. Numerical modeling shows that ground-penetrating radar (GPR) is sensitive to the presence of oil in the snow pack over a broad range of snow densities and oil types. Oil spills from the surface drain through the snow by the mechanisms of unsaturated flow and form geometrically complex distributions that are controlled by …

High-Precision U-Pb Zircon Age Calibration Of The Global Carboniferous Time Scale And Milankovitch Band Cyclicity In The Donets Basin, Eastern Ukraine, Vladimir I. Davydov, James L. Crowley, Mark D. Schmitz, Vladislav I. Poletaev

Geosciences Faculty Publications and Presentations

High-precision ID-TIMS U-Pb zircon ages for 12 interstratified tuffs and tonsteins are used to radiometrically calibrate the detailed lithostratigraphic, cyclostratigraphic, and biostratigraphic framework of the Carboniferous Donets Basin of eastern Europe. Chemical abrasion of zircons, use of the internationally calibrated EARTHTIME mixed U-Pb isotope dilution tracer, and improved mass spectrometry guided by detailed error analysis have resulted in an age resolution of

Ground Motion For The Maximum Credible Earthquake In Kentucky, Zhenming Wang

Report of Investigations--KGS

Although they are not frequent, earthquakes occur in and around Kentucky and pose certain hazards. Assessing seismic hazards is challenging, however, because of a lack of observations. The best estimates of ground motions that could be expected if the maximum credible earthquake occurs in or around Kentucky are depicted in maps showing peak ground acceleration and short-period (0.2 second) and long-period (1.0 second) response accelerations with 5 percent critical damping on hard rock. Another consideration for seismic safety is that the maximum credible earthquake has a long recurrenece interval, from 500 to 1,000 years in the New Madrid Seismic Zone …

Insights Into Rock-Ice Avalanche Dynamics By Combined Analysis Of Seismic Recordings And A Numerical Avalanche Mode, Demian Schneider, Perry Bartelt, Jacqueline Caplan-Auerbach, Marc Christen, Christian Huggel, Brian W. Mcardell

Geology Faculty Publications

Rock‐ice avalanches larger than 1 × 10⁶ m³ are high‐magnitude, low‐frequency events that may occur in all ice‐covered, high mountain areas around the world and can cause extensive damage if they reach populated regions. The temporal and spatial evolution of the seismic signature from two events was analyzed, and recordings at selected stations were compared to numerical model results of avalanche propagation. The first event is a rock‐ice avalanche from Iliamna volcano in Alaska which serves as a “natural laboratory” with simple geometric conditions. The second one originated on Aoraki/Mt. Cook, New Zealand Southern Alps, and is characterized …

A Study Of Fold Characteristics And Deformation Style Using The Evolution Of The Land Surface: Zagros Simply Folded Belt, Iran, Caroline M. Burberry, John W. Cosgrove, Jian-Guo Liu

Department of Earth and Atmospheric Sciences: Faculty Publications

Deformation styles within a fold-thrust belt can be understood in terms of the spatial organization and geometry of the fold structures. In young fold-thrust belts such as the Zagros, this geometry is reflected topographically by concordant landform morphology. Thus, the distribution of deformation structures can be characterized using satellite image analysis, digital elevation models, the drainage network and geomorphological indicators. The two distinct fold types considered in this study (fault-bend folds and detachment folds) both trending NW-SE, interact with streams flowing NE-SW from the High Zagros Mountains into the Persian Gulf. Multiple abandoned stream channels cross fault-bend folds related to …

Mixing By Shear Instability At High Reynolds Number, W. R. Geyer, A. C. Lavery, M. E. Scully, J. H. Trowbridge

CCPO Publications

Shear instability is the dominant mechanism for converting fluid motion to mixing in the stratified ocean and atmosphere. The transition to turbulence has been well characterized in laboratory settings and numerical simulations at moderate Reynolds number-it involves "rolling up", i.e., overturning of the density structure within the cores of the instabilities. In contrast, measurements in an energetic estuarine shear zone reveal that the mixing induced by shear instability at high Reynolds number does not primarily occur by overturning in the cores; rather it results from secondary shear instabilities within the zones of intensified shear separating the cores. This regime is …

Geochemical Investigation Of An Offshore Sewage Sludge Deposit, Barcelona, Catalonia, Spain, Michael A. Kruge, Albert Permanyer, Jordi Serra, Danlin Yu

Department of Earth and Environmental Studies Faculty Scholarship and Creative Works

For 20 years ending in the 1990’s the city of Barcelona discharged the products from a large primary sewage treatment plant directly into the Mediterranean Sea via underwater conduits. About ca. 3 million m³ of relict sewage sludge, rich in organic matter and heavy metals, has spread over an elongated area offshore, due to successive ruptures of the conduits. The use of the discharge pipes ceased, but he sludge deposit remains in place for the time being.

To understand the history and present state of the sludge deposit in advance of future remediation, a program of geophysical mapping, sampling, …