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2014

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Articles 331 - 360 of 360

Full-Text Articles in Geology

Nongeocentric Axial Dipole Field Behavior During The Mono Lake Excursion, Robert M. Negrini, Daniel T. Mccuan, Robert A. Horton, James D. Lopez, William S. Cassata, James E. T. Channell, Kenneth L. Verosub, Jeffrey R. Knott, Robert S. Coe, Joseph C. Liddicoat, Steven P. Lund, Larry Benson, Andrei M. Sarna-Wojcicki Jan 2014

Nongeocentric Axial Dipole Field Behavior During The Mono Lake Excursion, Robert M. Negrini, Daniel T. Mccuan, Robert A. Horton, James D. Lopez, William S. Cassata, James E. T. Channell, Kenneth L. Verosub, Jeffrey R. Knott, Robert S. Coe, Joseph C. Liddicoat, Steven P. Lund, Larry Benson, Andrei M. Sarna-Wojcicki

United States Geological Survey: Staff Publications

A new record of the Mono Lake excursion (MLE) is reported from the Summer Lake Basin of Oregon, USA. Sediment magnetic properties indicate magnetite as the magnetization carrier and imply suitability of the sediments as accurate recorders of the magnetic field including relative paleointensity (RPI) variations. The magnitudes and phases of the declination, inclination, and RPI components of the new record correlate well with other coeval but lower resolution records from western North America including records from the Wilson Creek Formation exposed around Mono Lake. The virtual geomagnetic pole (VGP) path of the new record is similar to that from …


Wetland Reserve Program Enhances Site Occupancy And Species Richness In Assemblages Of Anuran Amphibians In The Mississippi Alluvial Valley, Usa, Susan C. Walls, J. Hardin Waddle, Stephen P. Faulkner Jan 2014

Wetland Reserve Program Enhances Site Occupancy And Species Richness In Assemblages Of Anuran Amphibians In The Mississippi Alluvial Valley, Usa, Susan C. Walls, J. Hardin Waddle, Stephen P. Faulkner

United States Geological Survey: Staff Publications

We measured amphibian habitat use to quantify the effectiveness of conservation practices implemented under the Wetland Reserve Program (WRP), an initiative of the U.S. Department of Agriculture’s Natural Resources Conservation Service. From February to June 2007, we quantified calling male anurans in cultivated cropland, former cultivated cropland restored through the WRP, and mature bottomland hardwood forest. Sites were located in two watersheds within the Mississippi Alluvial Valley of Arkansas and Louisiana, USA. We estimated detection probability and site occupancy within each land use category using a Bayesian hierarchical model of community species occurrence, and derived an estimate of species richness …


Mapping Irrigated Areas In Afghanistan Over The Past Decade Using Modis Ndvi, Md. Shahriar Pervez, Michael Budde, James Rowland Jan 2014

Mapping Irrigated Areas In Afghanistan Over The Past Decade Using Modis Ndvi, Md. Shahriar Pervez, Michael Budde, James Rowland

United States Geological Survey: Staff Publications

Agricultural production capacity contributes to food security in Afghanistan and is largely dependent on irrigated farming, mostly utilizing surface water fed by snowmelt. Because of the high contribution of irrigated crops (> 80%) to total agricultural production, knowing the spatial distribution and year-to-year variability in irrigated areas is imperative to monitoring food security for the country. We used 16-day composites of the Normalized Difference Vegetation Index (NDVI) from the Moderate Resolution Imaging Spectroradiometer (MODIS) sensor to create 23-point time series for each year from 2000 through 2013. Seasonal peak values and time series were used in a threshold-dependent decision tree …


Structural Equation Models Of Vmt Growth In Us Urbanised Areas, Reid Ewing, Shima Hamidi, Frank Gallivan, Arthur C. Nelson, James B. Grace Jan 2014

Structural Equation Models Of Vmt Growth In Us Urbanised Areas, Reid Ewing, Shima Hamidi, Frank Gallivan, Arthur C. Nelson, James B. Grace

United States Geological Survey: Staff Publications

Vehicle miles travelled (VMT) is a primary performance indicator for land use and transportation, bringing with it both positive and negative externalities. This study updates and refines previous work on VMT in urbanised areas, using recent data, additional metrics and structural equation modelling (SEM). In a cross-sectional model for 2010, population, income and freeway capacity are positively related to VMT, while gasoline prices, development density and transit service levels are negatively related. Findings of the cross-sectional model are generally confirmed in a more tightly controlled longitudinal study of changes in VMT between 2000 and 2010, the first model of its …


Merging Remote Sensing Data And National Agricultural Statistics To Model Change In Irrigated Agriculture, Jesslyn F. Brown, Md Shahriar Pervez Jan 2014

Merging Remote Sensing Data And National Agricultural Statistics To Model Change In Irrigated Agriculture, Jesslyn F. Brown, Md Shahriar Pervez

United States Geological Survey: Staff Publications

Over 22 million hectares (ha) of U.S. croplands are irrigated. Irrigation is an intensified agricultural land use that increases crop yields and the practice affects water and energy cycles at, above, and below the land surface. Until recently, there has been a scarcity of geospatially detailed information about irrigation that is comprehensive, consistent, and timely to support studies tying agricultural land use change to aquifer water use and other factors. This study shows evidence for a recent overall net expansion of 522 thousand ha across the U.S. (2.33%) and 519 thousand ha (8.7%) in irrigated cropped area across the High …


Comparing Crop Land Net Primary Production Estimates From Inventory, A Satellite-Based Model, And A Process-Based Model In The Midwest Of The United States Zhengpeng, Zhengpeng Li, Shuguang Liu, Zhengxi Tan, Normann B. Bliss, Claudia J. Young, Tristram O. West, Stephen M. Ogle Jan 2014

Comparing Crop Land Net Primary Production Estimates From Inventory, A Satellite-Based Model, And A Process-Based Model In The Midwest Of The United States Zhengpeng, Zhengpeng Li, Shuguang Liu, Zhengxi Tan, Normann B. Bliss, Claudia J. Young, Tristram O. West, Stephen M. Ogle

United States Geological Survey: Staff Publications

Accurately quantifying the spatial and temporal variability of net primary production (NPP) for crop-lands is essential to understand regional cropland carbon dynamics. We compared three NPP estimates for croplands in the Midwestern United States: inventory-based estimates using crop yield data from the U.S. Department of Agriculture (USDA) National Agricultural Statistics Service (NASS); estimates from the satellite-based Moderate Resolution Imaging Spectro radiometer (MODIS) NPP product; and esti-mates from the General Ensemble bio geochemical Modeling System (GEMS) process-based model. The three methods estimated mean NPP in the range of 469–687 g C m−2yr−1and total NPP in the range …


Summary Of The Snowmastodon Project Special Volume: A High-Elevation, Multi-Proxy Biotic And Environmental Record Of Mis 6–4 From The Ziegler Reservoir Fossil Site, Snowmass Village, Colorado, Usa, Ian M. Miller, Jeffrey S. Pigati, R. Scott Anderson, Kirk R. Johnson, Shannon A. Mahan, Thomas A. Ager, Richard G. Baker, Maarten Blaauw, Jordon Bright, Peter M. Brown, Bruce Bryant, Zachary T. Calamari, Paul E. Carrara, Michael D. Cherney, John R. Demboski, Scott A. Elias, Daniel C. Fisher, Harrison J. Gray, Danielle R. Haskett, Jeffrey S. Honke, Stephen T. Jackson, Gonzalo Jiménez- Moreno, Douglas Kline, Eric M. Leonard, Nathaniel A. Lifton, Carol Lucking, H. Gregory Mcdonald, Dane M. Miller, Daniel R. Muhs, Stephen E. Nash, Cody Newton, James B. Paces, Lesley Petrie, Mitchell A. Plummer, David F. Porinchu, Adam N. Rountrey, Eric Scott, Joseph J.W. Sertich, Saxon E. Sharpe, Gary L. Skipp, Laura E. Strickland, Richard K. Stucky, Robert S. Thompson, Jim Wilson Jan 2014

Summary Of The Snowmastodon Project Special Volume: A High-Elevation, Multi-Proxy Biotic And Environmental Record Of Mis 6–4 From The Ziegler Reservoir Fossil Site, Snowmass Village, Colorado, Usa, Ian M. Miller, Jeffrey S. Pigati, R. Scott Anderson, Kirk R. Johnson, Shannon A. Mahan, Thomas A. Ager, Richard G. Baker, Maarten Blaauw, Jordon Bright, Peter M. Brown, Bruce Bryant, Zachary T. Calamari, Paul E. Carrara, Michael D. Cherney, John R. Demboski, Scott A. Elias, Daniel C. Fisher, Harrison J. Gray, Danielle R. Haskett, Jeffrey S. Honke, Stephen T. Jackson, Gonzalo Jiménez- Moreno, Douglas Kline, Eric M. Leonard, Nathaniel A. Lifton, Carol Lucking, H. Gregory Mcdonald, Dane M. Miller, Daniel R. Muhs, Stephen E. Nash, Cody Newton, James B. Paces, Lesley Petrie, Mitchell A. Plummer, David F. Porinchu, Adam N. Rountrey, Eric Scott, Joseph J.W. Sertich, Saxon E. Sharpe, Gary L. Skipp, Laura E. Strickland, Richard K. Stucky, Robert S. Thompson, Jim Wilson

United States Geological Survey: Staff Publications

In North America, terrestrial records of biodiversity and climate change that span Marine Oxygen Isotope Stage (MIS) 5 are rare. Where found, they provide insight into how the coupling of the ocean–atmosphere system is manifested in biotic and environmental records and how the biosphere responds to climate change. In 2010–2011, construction at Ziegler Reservoir near Snowmass Village, Colorado (USA) revealed a nearly continuous, lacustrine/wetland sedimentary sequence that preserved evidence of past plant communities between ~140 and 55 ka, including all of MIS 5. At an elevation of 2705 m, the Ziegler Reservoir fossil site also contained thousands of well-preserved bones …


Radiocarbon Dating Loess Deposits In The Mississippi Valley Using Terrestrial Gastropod Shells (Polygyridae, Helicinidae, And Discidae), Jeffrey S. Pigati, John Mcgeehin, Daniel R. Muhs, David A. Grimley, Jeffrey C. Nekola Jan 2014

Radiocarbon Dating Loess Deposits In The Mississippi Valley Using Terrestrial Gastropod Shells (Polygyridae, Helicinidae, And Discidae), Jeffrey S. Pigati, John Mcgeehin, Daniel R. Muhs, David A. Grimley, Jeffrey C. Nekola

United States Geological Survey: Staff Publications

Small terrestrial gastropod shells (mainly Succineidae) have been used successfully to date late Quaternary loess deposits in Alaska and the Great Plains. However, Succineidae shells are less common in loess deposits in the Mississippi Valley compared to those of the Polygyridae, Helicinidae, and Discidae families. In this study, we conducted several tests to determine whether shells of these gastropods could provide reliable ages for loess deposits in the Mississippi Valley. Our results show that most of the taxa that we investigated incorporate small amounts (1–5%) of old carbon from limestone in their shells, meaning that they should yield ages that …


Geologic Setting And Stratigraphy Of The Ziegler Reservoir Fossil Site, Snowmass Village, Colorado, Jeffrey S. Pigati, Ian M. Miller, Kirk R. Johnson, Jeffrey S. Honke, Paul E. Carrara, Daniel R. Muhs, Gary Skipp, Bruce Bryant Jan 2014

Geologic Setting And Stratigraphy Of The Ziegler Reservoir Fossil Site, Snowmass Village, Colorado, Jeffrey S. Pigati, Ian M. Miller, Kirk R. Johnson, Jeffrey S. Honke, Paul E. Carrara, Daniel R. Muhs, Gary Skipp, Bruce Bryant

United States Geological Survey: Staff Publications

The geologic setting of the Ziegler Reservoir fossil site is somewhat unusual—the sediments containing the Pleistocene fossils were deposited in a lake on top of a ridge. The lake basin was formed near Snowmass Village, Colorado (USA) when a glacier flowing down Snowmass Creek Valley became thick enough to overtop a low point in the eastern valley wall and entered the head of Brush Creek Valley. When the glacier retreated at about 155–130 ka, near the end of Marine Oxygen Isotope Stage 6, the Brush Creek Valley lobe left behind a moraine that impounded a small alpine lake. The lake …


Toxicity Of Pb‐Contaminated Soil To Japanese Quail (Coturnix Japonica) And The Use Of The Blood–Dietary Pb Slope In Risk Assessment, W. Nelson Beyer, Yu Chen, Paula Henry, Thomas May, David Mosby, Barnett A. Rattner, Valerie I. Shearn-Bochsler, Daniel Sprague, John Weber Jan 2014

Toxicity Of Pb‐Contaminated Soil To Japanese Quail (Coturnix Japonica) And The Use Of The Blood–Dietary Pb Slope In Risk Assessment, W. Nelson Beyer, Yu Chen, Paula Henry, Thomas May, David Mosby, Barnett A. Rattner, Valerie I. Shearn-Bochsler, Daniel Sprague, John Weber

United States Geological Survey: Staff Publications

This study relates tissue concentrations and toxic effects of Pb in Japanese quail (Coturnix japonica) to the dietary exposure of soil‐borne Pb associated with mining and smelting. From 0% to 12% contaminated soil, by weight, was added to 5 experimental diets (0.12 to 382mg Pb/kg, dry wt) and fed to the quail for 6 weeks. Benchmark doses associated with a 50% reduction in delta‐aminolevulinic acid dehydratase activity were 0.62mg Pb/kg in the blood, dry wt, and 27mg Pb/kg in the diet. Benchmark doses associated with a 20% increase in the concentration of erythrocyte protoporphyrin were 2.7mg Pb/kg in …


Testing Metapopulation Concepts: Effects Of Patch Characteristics And Neighborhood Occupancy On The Dynamics Of An Endangered Lagomorph, Mitchell J. Eaton, Phillip T. Hughes, James E. Hines, James D. Nichols Jan 2014

Testing Metapopulation Concepts: Effects Of Patch Characteristics And Neighborhood Occupancy On The Dynamics Of An Endangered Lagomorph, Mitchell J. Eaton, Phillip T. Hughes, James E. Hines, James D. Nichols

United States Geological Survey: Staff Publications

Metapopulation ecology is a field that is richer in theory than in empirical results. Many existing empirical studies use an incidence function approach based on spatial patterns and key assumptions about extinction and colonization rates. Here we recast these assumptions as hypotheses to be tested using 18 years of historic detection survey data combined with four years of data from a new monitoring program for the Lower Keys marsh rabbit. We developed a new model to estimate probabilities of local extinction and colonization in the presence of nondetection, while accounting for estimated occupancy levels of neighboring patches. We used model …


Probit Models For Capture-Recapture Data Subject To Imperfect Detection, Individual Heterogeneity And Misidentification, Brett T. Mcclinktock, Larissa L. Bailey, Brian P. Dreher, William A. Link Jan 2014

Probit Models For Capture-Recapture Data Subject To Imperfect Detection, Individual Heterogeneity And Misidentification, Brett T. Mcclinktock, Larissa L. Bailey, Brian P. Dreher, William A. Link

United States Geological Survey: Staff Publications

As noninvasive sampling techniques for animal populations have become more popular, there has been increasing interest in the development of capture-recapture models that can accommodate both imperfect detection and misidentification of individuals (e.g., due to genotyping error). However, current methods do not allow for individual variation in parameters, such as detection or survival probability. Here we develop misidentification models for capture-recapture data that can simultaneously account for temporal variation, behavioral effects and individual heterogeneity in parameters. To facilitate Bayesian inference using our approach, we extend standard probit regression techniques to latent multinomial models where the dimension and zeros of the …


Testing Metapopulation Concepts: Effects Of Patch Characteristics And Neighborhood Occupancy On The Dynamics Of An Endangered Lagomorph, Mitchell J. Eaton, Phillip T. Hughes, James E. Hines, James D. Nichols Jan 2014

Testing Metapopulation Concepts: Effects Of Patch Characteristics And Neighborhood Occupancy On The Dynamics Of An Endangered Lagomorph, Mitchell J. Eaton, Phillip T. Hughes, James E. Hines, James D. Nichols

United States Geological Survey: Staff Publications

Metapopulation ecology is a field that is richer in theory than in empirical results. Many existing empirical studies use an incidence function approach based on spatial patterns and key assumptions about extinction and colonization rates. Here we recast these assumptions as hypotheses to be tested using 18 years of historic detection survey data combined with four years of data from a new monitoring program for the Lower Keys marsh rabbit. We developed a new model to estimate probabilities of local extinction and colonization in the presence of nondetection, while accounting for estimated occupancy levels of neighboring patches. We used model …


Probit Models For Capture-Recapture Data Subject To Imperfect Detection, Individual Heterogeneity And Misidentification1, Brett T. Mcclintock, Larissa L. Bailey, Brian P. Dreher, William A. Link Jan 2014

Probit Models For Capture-Recapture Data Subject To Imperfect Detection, Individual Heterogeneity And Misidentification1, Brett T. Mcclintock, Larissa L. Bailey, Brian P. Dreher, William A. Link

United States Geological Survey: Staff Publications

As noninvasive sampling techniques for animal populations have become more popular, there has been increasing interest in the development of capture-recapture models that can accommodate both imperfect detection and misidentification of individuals (e.g., due to genotyping error). However, current methods do not allow for individual variation in parameters, such as detection or survival probability. Here we develop misidentification models for capture-recapture data that can simultaneously account for temporal variation, behavioral effects and individual heterogeneity in parameters. To facilitate Bayesian inference using our approach, we extended standard probit regression techniques to latent multinomial models where the dimension and zeros of the …


Loess Records, Daniel R. Muhs, Stephen R. Cattle, Onn Crouvi, Denis-Didier Rousseau, Jimin Sun, Marcelo A. Zárate Jan 2014

Loess Records, Daniel R. Muhs, Stephen R. Cattle, Onn Crouvi, Denis-Didier Rousseau, Jimin Sun, Marcelo A. Zárate

United States Geological Survey: Staff Publications

Loess is aeolian sediment, dominated by silt-sized particles, that is identifiable in the field as a distinct sedimentary body. It covers a significant portion of the land surface of the Earth and as such constitutes one of the most important archives of long-term dust deposition. Large tracts of loess cover Europe, Asia, South America, and North America, and smaller loess bodies are found covering parts of Africa, the Middle East, New Zealand, and Australia. Loess thickness, particle size, and carbonate content decrease downwind from sources, trends that are powerful tools for reconstructing paleowinds. Many loess sections consist of relatively thick …


Evidence Of Repeated Wildfires Prior To Human Occupation On San Nicolas Island, California, Jeffrey S. Pigati, John P. Mcgeehin, Gary L. Skipp, Daniel R. Muhs Jan 2014

Evidence Of Repeated Wildfires Prior To Human Occupation On San Nicolas Island, California, Jeffrey S. Pigati, John P. Mcgeehin, Gary L. Skipp, Daniel R. Muhs

United States Geological Survey: Staff Publications

Understanding how early humans on the California Channel Islands might have changed local fire regimes requires a baseline knowledge of the frequency of natural wildfires on the islands prior to human occupation. A sedimentary sequence that was recently discovered in a small canyon on San Nicolas Island contains evidence of at least 24 burn events that date to between ~37 and 25 ka (thousands of calibrated 14C years before present), well before humans entered North America. The evidence includes abundant macroscopic charcoal, blackened sediments, and discrete packages of oxidized, reddish-brown sediments that are similar in appearance to sedimentary features …


Simultaneous Adsorption Of 11 Volatile Organic Compounds By An Activated Carbon Made From Polystyrene Sulfonic Acid-Based Organic Salt, Alejandro Smith Jan 2014

Simultaneous Adsorption Of 11 Volatile Organic Compounds By An Activated Carbon Made From Polystyrene Sulfonic Acid-Based Organic Salt, Alejandro Smith

Dissertations and Theses

Activated carbon is used in water treatment worldwide due to its ability to adsorb many different contaminants from water. The high adsorption capacity of activated carbon is linked to its high internal surface area and micro/meso- porosity. In this work an activated carbon obtained from polystyrene sulfonic acid-based organic salt was examined to simultaneously adsorb eleven volatile organic compounds from aqueous solution. Adsorption data were modeled with different isotherms to determine the equilibrium adsorptive capacities for these compounds. The performance of the polymer-based activated carbon was then compared with that of a commercial wood-based activated carbon. The results indicate that …


Calcite Dissolution Under Turbulent Flow Conditions: A Remaining Conundrum, Matthew D. Covington Jan 2014

Calcite Dissolution Under Turbulent Flow Conditions: A Remaining Conundrum, Matthew D. Covington

Geosciences Faculty Publications and Presentations

A significant body of experimental and theoretical work has examined the dissolution rates of calcite, and other carbonate minerals, under varying chemical and hydrodynamic conditions (see Morse & Arvidson (2002) for a comprehensive review). The relationships derived from this work have been applied extensively to the development of mechanistic models of speleogenesis (e.g. Dreybrodt 1996; Dreybrodt et al. 2005; Birk et al. 2005; Rehrl et al. 2008; Kaufmann 2009; Szymczak & Ladd 2011). However, the primary focus of these models has been on the early stages of cave formation, with less attention toward the later stages of cave evolution and …


Geoneutrino Production Of The Northern Black Hills, South Dakota, United States Of America, Eric Eric Zimney Jan 2014

Geoneutrino Production Of The Northern Black Hills, South Dakota, United States Of America, Eric Eric Zimney

Theses and Dissertations

Current neutrino observatories operate underground to isolate the detector from cosmic rays and background radiation. However, background radiation from local sources has yet to be accounted for. Current models for neutrino contributions from terrestrial rocks are formulated from bulk compositional estimates of the whole Earth. To better understand local background radiation from geologic sources surfaces rocks were collected throughout the area surrounding the Homestake Mine, South Dakota, home of the Sanford Underground Research Laboratory. The surface rocks were analyzed for radioactivity and neutrino luminosity, producing heat maps indicating the levels of neutrino production throughout the area. The area around the …


Classification Of Four Meteorite Samples, Karla Farley Jan 2014

Classification Of Four Meteorite Samples, Karla Farley

University Honors Theses

The petrography, mineralogy, and mineral chemistry of four unclassified Northwest Africa meteorites in the Cascadia Meteorite Laboratory collection (CML0005, 0023, 0024, 0032) were studied using optical microscopy and scanning electron microscopy. The data will be used to classify the meteorites and to obtain official names for the meteorites. CML0023 has the preliminary classification of L6 (S3) W1, CML0024 has L6 (S3) W1, and CML0032 has L6 (S2) W1. CML0005 has chemistry and mineralogy that indicate it is an anomalous acapulcoite.


Investigation Of Strategies To Promote Effective Teacher Professional Development Experiences In Earth Science, Carol A. Engelmann Jan 2014

Investigation Of Strategies To Promote Effective Teacher Professional Development Experiences In Earth Science, Carol A. Engelmann

Dissertations, Master's Theses and Master's Reports - Open

This dissertation serves as a call to geoscientists to share responsibility with K-12 educators for increasing Earth science literacy. When partnerships are created among K-12 educators and geoscientists, the synergy created can promote Earth science literacy in students, teachers, and the broader community. The research described here resulted in development of tools that can support effective professional development for teachers. One tool is used during the planning stages to structure a professional development program, another set of tools supports measurement of the effectiveness of a development program, and the third tool supports sustainability of professional development programs. The Michigan Teacher …


Doing More With Short Period Data: Determining Magnitudes From Clipped And Over-Run Seismic Data At Mount St. Helens, John J. Wellik Ii Jan 2014

Doing More With Short Period Data: Determining Magnitudes From Clipped And Over-Run Seismic Data At Mount St. Helens, John J. Wellik Ii

Dissertations, Master's Theses and Master's Reports - Open

How can we calculate earthquake magnitudes when the signal is clipped and over-run? When a volcano is very active, the seismic record may saturate (i.e., the full amplitude of the signal is not recorded) or be over-run (i.e., the end of one event is covered by the start of a new event). The duration, and sometimes the amplitude, of an earthquake signal are necessary for determining event magnitudes; thus, it may be impossible to calculate earthquake magnitudes when a volcano is very active. This problem is most likely to occur at volcanoes with limited networks of short period seismometers. This …


Static And Dynamic Stress Change At 27 Volcanoes Of The Central American Volcanic Arc After The Mw. 7.6 Costa Rica Earthquake Of 5 September 2012, Lorenzo Gratton Jan 2014

Static And Dynamic Stress Change At 27 Volcanoes Of The Central American Volcanic Arc After The Mw. 7.6 Costa Rica Earthquake Of 5 September 2012, Lorenzo Gratton

Dissertations, Master's Theses and Master's Reports - Open

Large earthquakes may strongly influence the activity of volcanoes through static and dynamic processes. In this study, we quantify the static and dynamic stress change on 27 volcanoes in Central America, after the Mw 7.6 Costa Rica earthquake of 5 September 2012. Following this event, 8 volcanoes showed signs of activity. We calculated the static stress change due to the earthquake on hypothetical faults under these volcanoes with Coulomb 3.3. For the dynamic stress change, we computed synthetic seismograms to simulate the waveforms at these volcanoes. We then calculated the Peak Dynamic Stress (PDS) from the modeled peak ground …


Fault Morphology Within The Southern Kenyan Portion Of The East African Rift Valley, Justin B. Wargelin Jan 2014

Fault Morphology Within The Southern Kenyan Portion Of The East African Rift Valley, Justin B. Wargelin

Dissertations, Master's Theses and Master's Reports - Open

Faults form quickly, geologically speaking, with sharp, crisp step-like profiles. Logic dictates that erosion wears away this "sharpness" or angularity creating more rounded features. As erosion occurs, debris accumulates at the base of the scarp slope. The stable end point of this process is when the scarp slope approaches an ideal sigmoid shape.

This theory of fault end process, in combination with a new method developed in this report for fault profile delineation, has the potential to enable observation and categorization of fault profiles over large, diverse swaths of fault formation-- in remote areas such as the Southern Kenyan Rift …


Did A Submarine Landslide Contribute To The 2011 Tohoku Tsunami?, David R. Tappin, Stephan T. Grilli, Jeffrey C. Harris, Robert J. Geller, Timothy Masterlark, James T. Kirby, Fengyan Shi, Gangfeng Ma, K.K.S. Thingbaijam, P. Martin Mai Jan 2014

Did A Submarine Landslide Contribute To The 2011 Tohoku Tsunami?, David R. Tappin, Stephan T. Grilli, Jeffrey C. Harris, Robert J. Geller, Timothy Masterlark, James T. Kirby, Fengyan Shi, Gangfeng Ma, K.K.S. Thingbaijam, P. Martin Mai

Civil & Environmental Engineering Faculty Publications

Many studies have modeled the Tohoku tsunami of March 11, 2011 as being due entirely to slip on an earthquake fault, but the following discrepancies suggest that further research is warranted. (1) Published models of tsunami propagation and coastal impact underpredict the observed runup heights of up to 40. m measured along the coast of the Sanriku district in the northeast part of Honshu Island. (2) Published models cannot reproduce the timing and high-frequency content of tsunami waves recorded at three nearshore buoys off Sanriku, nor the timing and dispersion properties of the waveforms at offshore DART buoy #21418. (3) …


Seismic Anisotropy And Mantle Flow Beneath Africa And Arabia, Ahmed Abdalla Elsheikh Jan 2014

Seismic Anisotropy And Mantle Flow Beneath Africa And Arabia, Ahmed Abdalla Elsheikh

Doctoral Dissertations

"In spite of numerous studies, the mechanisms for the rifting, uplifting, and volcanism on the African plate remain enigmatic. The most popular hypotheses proposed for explaining these tectonic phenomena involve edge-driven small-scale mantle convection and the thermal or dynamic effects of one or more mantle plumes. In this study we use continental scale shear-wave splitting (SWS) measurements to provide additional constraints on the various models of rifting, uplifting, and volcanism of the Cameroon Volcanic Line (CVL) and the Arabian plate. The splitting of P-to-S converted phases at the core-mantle boundary on the receiver side (XKS including PKS, SKKS, and SKS) …


Biomineralization Of Carbonates In Modern Microbial Sediments And Its Implications For Co₂ Sequestration, Varun Gnanaprian Paul Jan 2014

Biomineralization Of Carbonates In Modern Microbial Sediments And Its Implications For Co₂ Sequestration, Varun Gnanaprian Paul

Doctoral Dissertations

"Several bacterial species influence carbonate mineral precipitation by modifying pH, alkalinity, Ca²⁺ activity and by providing nucleation sites for mineralization. Two studies have been undertaken to explore microbial influence in the mineralization of carbonates. In the first study, the ability of sulfate-reducing bacteria (SRB) to induce carbonate mineralization was investigated as a means to enhance mineral sequestration of CO₂. Sulfate-reducing bacteria enriched from hypersaline Storr's Lake, The Bahamas; Lake Estancia, New Mexico; and Great Salt Plains Lake, Oklahoma, were tested in reactors under varying CO₂ concentrations. Carbonate mineral precipitation was achieved only in reactors with Lake Estancia SRB community and …


Study Of Filled Dolines By Using 3d Stereo Image Processing And Electrical Resistivity Imaging, Mateja Breg Valjavec Jan 2014

Study Of Filled Dolines By Using 3d Stereo Image Processing And Electrical Resistivity Imaging, Mateja Breg Valjavec

International Journal of Speleology

This article deals with doline degradation due to uncontrolled waste dumping in the past in the Logatec Polje in Slovenia. It introduces a concept for determining 3D geometric characteristics (shape, depth, radius, area, and volume) of formerly concave landforms (i.e., recently filled dolines) by using a combination of two methods: (1) photogrammetric stereo processing of archival aerial photographs and (2) electrical resistivity imaging (ERI). To represent, visualize, and study the characteristics of the former surface morphology (i.e., the dolines before they were filled), a digital terrain model (DTM) for 1972 (DTM1972) was made using digital photogrammetry processing of five sequential …


Upper Pleistocene And Holocene Palaeoenvironmental Records In Cueva Mayor Karst (Atapuerca, Spain) From Different Proxies: Speleothem Crystal Fabrics, Palynology And Archaeology., Virginia Martínez-Pillado, Arantza Aranburu, Juan Luis Arsuaga, Blanca Ruiz-Zapata, Maria José Gil-García, Heather Stoll, Iñaki Yusta, Eneko Iriarte, José Miguel Carretero, R. Lawrence Edwards, Hai Cheng Jan 2014

Upper Pleistocene And Holocene Palaeoenvironmental Records In Cueva Mayor Karst (Atapuerca, Spain) From Different Proxies: Speleothem Crystal Fabrics, Palynology And Archaeology., Virginia Martínez-Pillado, Arantza Aranburu, Juan Luis Arsuaga, Blanca Ruiz-Zapata, Maria José Gil-García, Heather Stoll, Iñaki Yusta, Eneko Iriarte, José Miguel Carretero, R. Lawrence Edwards, Hai Cheng

International Journal of Speleology

The Cueva Mayor karst system of Atapuerca, in Northern Spain, hosts a highly significant record of human occupation from the Pleistocene. The climatic context of the human activities during the Pleistocene-Holocene for this inland site has not been well constrained, since existing records of the palaeoclimatic evolution of the Northern Iberian Peninsula are from more distal coastal and high-elevation sites. In this study, we interpret the palaeoenvironmental information recorded on the petrography of a stalagmite and the pollen spectra of the Sierra de Atapuerca karst system during the last 20 kyr. The integration of both types of records has allowed …


Electron Donor Contributions To Denitrification In The Elk Valley Aquifer, North Dakota, Amanda M. Krieger Jan 2014

Electron Donor Contributions To Denitrification In The Elk Valley Aquifer, North Dakota, Amanda M. Krieger

Theses and Dissertations

Six denitrification tracer tests were performed over eight and a half years in in situ mesocosms (ISMs) in the Elk Valley Aquifer (EVA) in east-central North Dakota. Groundwater samples were analyzed to determine how much nitrate was lost beyond that explained by dilution of the bromide tracer. Additional losses were attributed to denitrification. The denitrification rates varied from 0.10 to 0.23 mg N/L/day for the six tests. In general, the major electron donors for denitrification are organic carbon (OC), pyrite (FeS2), and ferrous iron silicate minerals. In the EVA tracer tests, increases in sulfate indicated that the oxidation of pyrite …