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Articles 1111 - 1140 of 1252
Full-Text Articles in Earth Sciences
Rhyolite And Trachyte Formation At Lake City Caldera: Insight From Quantitative Textural And Geochemical Analyses, Jordan Lubbers
Rhyolite And Trachyte Formation At Lake City Caldera: Insight From Quantitative Textural And Geochemical Analyses, Jordan Lubbers
Dissertations, Master's Theses and Master's Reports
Lake City Caldera (22.93 ± 0.02 Ma) is the youngest of 15 Tertiary calderas found within the Southern Rocky Mountain Volcanic Field (SRMVF). Extreme topographical relief of the area reveals the three dimensional exposure of a complex, high-k calc-alkaline, magmatic system, which provides us with the opportunity to study, in detail, how large silicic magmas evolve in the subsurface. The Lake City igneous system is comprised of two major units: a resurgent syenite intrusion and the Sunshine Peak Tuff (Lower, Middle, and Upper). Bulk-rock analyses indicate that the Lower and Middle Sunshine Peak tuff are crystal poor and rhyolitic in …
Petrophysical And Empirical And Theoretical Rock Physics Modeling For The Moki Formation In Two Fields In The Taranaki Basin, New Zealand, Deniz Yener
Dissertations, Master's Theses and Master's Reports
This work consists of conventional petrophysical analysis and sonic response determination from empirical relations, rock physics modelling, and fluid substitution for six wells in the Moki formation of New Zealand’s Taranaki Basin. The project composed of three parts encompassing conventional log analysis, rock-physics modeling using empirical and theoretical approaches, and finally rock-physics modeling for shaley sands using semi-empirical adaptations to Gassmann fluid substitution. Finally, comparisons are made between results for the different wells, based on their depths and mineralogy.
The first part of this study is presented as a petrophysical analysis, including crossplot analysis, conventional 3-mineral identification approach, and determination …
Cave Detection Using Seismic Methods At Madison Blue Spring State Park, Madison County, Florida, Charles Breithaupt
Cave Detection Using Seismic Methods At Madison Blue Spring State Park, Madison County, Florida, Charles Breithaupt
Dissertations, Master's Theses and Master's Reports
Locating caves and quantifying their geometries has significant importance in aquifer characterization, sinkhole mitigation, and contaminant transport monitoring. Several geophysical methods have been used for cave detection with limited success, but no reliable solution has been found. New developments in seismic techniques, however, show promising results indicating that cave voids may be more accurately detected.
We evaluated the capability of several seismic techniques to detect caves by collecting new seismic data over a known conduit connected to Madison Blue Spring, in northern Florida. These analyses validated the abilities of diffracted surface waves to detect water-filled caves by viewing these data …
Enhancement Of Margrave Deconvolution And Q Estimation In Highly Attenuating Media Using The Modified S-Transform, Adnan Djeffal
Enhancement Of Margrave Deconvolution And Q Estimation In Highly Attenuating Media Using The Modified S-Transform, Adnan Djeffal
Dissertations, Master's Theses and Master's Reports
We evaluate the performance of the Margrave deconvolution and spectral ratio methods using the Gabor, S-, and modified S transforms in highly attenuating media, where the quality factor changes with depth dramatically. Our results substantiate that the modified S-transform deconvolution is more robust in terms of generating fewer artifacts and providing better estimates of reflectivities than the Gabor transform. The results also show that using the modified S-transform in the spectral ratio method produces better Q estimates than the S-transform and the Fourier transform that is conventionally used in the spectral ratio method. This improvement in the estimates of reflectivities …
Reservoir Characterization Through Pre-Stack Seismic Analysis And Inversion In The Thrace Basin, Northwest Turkey, Emre Doguturk
Reservoir Characterization Through Pre-Stack Seismic Analysis And Inversion In The Thrace Basin, Northwest Turkey, Emre Doguturk
Dissertations, Master's Theses and Master's Reports
This study analyzes hydrocarbon reservoirs by using Amplitude-Versus-Offset (AVO) analysis and different inversion methods to investigate hydrocarbon reservoir in the Thrace Basin which is located in northwest Turkey.
A 3D seismic survey containing prestack data was provided by Turkish Petroleum Corporation as true amplitude NMO corrected 3D gathers.
The quality of this land data was poor for AVO applications, and steps were taken to make it useful. Radon filtering proved to be extremely useful for this purpose. Although application of this filter affected the AVO characteristics differently depending on the parameters selected for the filter, relative AVO characteristics remained useful …
Modeling Spring Catchment Discharge: A Case Study Of Candela, Panama, Central America, Jordan P. Van Sickle
Modeling Spring Catchment Discharge: A Case Study Of Candela, Panama, Central America, Jordan P. Van Sickle
Dissertations, Master's Theses and Master's Reports
Where the proper geological and hydrological conditions exist, natural springs have provided a reliable source of clean water to mankind for eons. Changing climates and land development can negatively impact spring source replenishment and threaten their reliability as a source of water. In the face of prospects of diminishing supplies and increasing population demands, community leaders question whether and how to invest in development for enhancing sustainability and protecting water quality, causing water managers to dispute their reliability given decreasing flows. Springs located in the rugged jungle of western Panama serve as the primary water supply for many indigenous communities, …
Preliminary Seismic Coda Wave Attenuation Study Of Pacaya Volcano, Guatemala, Maximilian Guettinger
Preliminary Seismic Coda Wave Attenuation Study Of Pacaya Volcano, Guatemala, Maximilian Guettinger
Dissertations, Master's Theses and Master's Reports
Pacaya volcano is a basaltic complex in the Central American Volcanic Arc in Guatemala. Pacaya has been in an open vent condition since 1961. During January 2015 we deployed 19 short period seismometer stations on Pacaya at distances less than 1.5 kilometers from the summit. The resulting data consisted of tremor and thousands of discrete events associated with ongoing outgassing. Where possible, individual events were identified and located. They were found to be high in the edifice near the vent. We used the decaying codas of these events to model the attenuation structure of the Pacaya edifice, following the energy …
Strike-Slip Neotectonic Regime And Related Structures In The Cappadocia Region: A Case Study In The Salanda Basin, Central Anatolia, Turkey, Ali̇ Koçyi̇ği̇t, Uğur Doğan
Strike-Slip Neotectonic Regime And Related Structures In The Cappadocia Region: A Case Study In The Salanda Basin, Central Anatolia, Turkey, Ali̇ Koçyi̇ği̇t, Uğur Doğan
Turkish Journal of Earth Sciences
The study area is a strike-slip basin of approximately 1-9 km wide, 66 km long and N65°W trending, located between the historical Kesikköprü in the west and the Sarıhıdır settlement in the east along the northern side of the Central Anatolian Volcanic Province. It was evolved on a regional erosional surface of a pre-Quaternary volcanosedimentary sequence during Quaternary. This is evidenced by the stratigraphical, structural, and seismic data. The total amounts of throw and dextral strike-slip displacement accumulated on the basin-boundary faults during the evolutionary history of the basin are 178 m and 5 km, respectively. The average slip rate …
Application Of Time-Frequency Analysis To Characterize Gas Shadows From The Clinton Interval In Ohio Seismic Reflection Data, Fangzhou Yan
Application Of Time-Frequency Analysis To Characterize Gas Shadows From The Clinton Interval In Ohio Seismic Reflection Data, Fangzhou Yan
Browse all Theses and Dissertations
The Smoothed Pseudo Wigner-Ville Distribution (SPWVD) is one method to simultaneously resolve time series in both time and frequency domains, allowing determination of frequency variation with time in non-stationary signals. Also, SPWVD reduces the cross-term interference. This analysis was applied to stacked, migrated seismic reflection data from Ohio to characterize gas shadows produced by known and potential gas reservoirs in the Clinton interval. In northeast Ohio, the Clinton interval is identified as occurring immediately beneath the Dayton Limestone, which is known as the driller’s Packer Shell in the subsurface. The analysis was first applied to a seismic reflection line acquired …
A Multi-Sensor View Of The 2012 Central Plains Drought From Space, Jun Wang, Amy L. Kessner, Clint Aegerter, Ambrish Sharma, Laura Judd, Brian D. Wardlow, Jinsheng You, Martha Shulski, Suat Irmak, Ayse Kilic, Jing Zeng
A Multi-Sensor View Of The 2012 Central Plains Drought From Space, Jun Wang, Amy L. Kessner, Clint Aegerter, Ambrish Sharma, Laura Judd, Brian D. Wardlow, Jinsheng You, Martha Shulski, Suat Irmak, Ayse Kilic, Jing Zeng
Department of Earth and Atmospheric Sciences: Faculty Publications
In summer of 2012, the Central Plains of the United States experienced its most severe drought since the ground-based data record began in the late 1900s. By using comprehensive satellite data from MODIS (Moderate Resolution Imaging Spectroradiometer) and TRMM (Tropical Rainfall Measuring Mission), along with in-situ observations, this study documents the geophysical parameters associated with this drought, and thereby providing, for the first time, a large-scale observation-based view of the extent to which the land surface temperature and vegetation can likely be affected by both the severe drought and the agricultural response (irrigation) to the drought. Over non-irrigated area, 2012 …
Accommodation Of Penetrative Strain During Deformation Above A Ductile Décollement, Bailey A. Lathrop, Caroline M. Burberry
Accommodation Of Penetrative Strain During Deformation Above A Ductile Décollement, Bailey A. Lathrop, Caroline M. Burberry
Department of Earth and Atmospheric Sciences: Faculty Publications
The accommodation of shortening by penetrative strain is widely considered as an important process during contraction, but the distribution and magnitude of penetrative strain in a contractional system with a ductile décollement are not well understood. Penetrative strain constitutes the proportion of the total shortening across an orogen that is not accommodated by the development of macroscale structures, such as folds and thrusts. In order to create a framework for understanding penetrative strain in a brittle system above a ductile décollement, eight analog models, each with the same initial configuration, were shortened to different amounts in a deformation apparatus. Models …
Late Glacial And Holocene History Of The Penobscot River In The Penobscot Lowland, Maine, Roger Leb. Hooke, Paul R. Hanson, Danile F. Belknap, Alice R. Kelley
Late Glacial And Holocene History Of The Penobscot River In The Penobscot Lowland, Maine, Roger Leb. Hooke, Paul R. Hanson, Danile F. Belknap, Alice R. Kelley
Conservation and Survey Division: Faculty and Staff Publications
When the Laurentide ice sheet retreated rapidly (~150 m/a) across the Penobscot Lowland between ~16 and ~15 ka, the area was isostatically depressed and became inundated by the sea. Silt and clay were deposited, but no significant moraines or deltas were formed. The Penobscot River was reborn at ~14 ka when ice retreated onto land in the upper reaches of the river’s East Branch. As isostatic rebound exceeded sea level rise from melting ice, the river extended itself southward. Between ~13.4 and 12.8 ka, it established a course across marine clay and underlying glacial till in the Lowland. Its gradient …
Developing The Framework For A Risk Map For Mite Vectored Viruses In Wheat Resulting From Pre-Harvest Hail Damage, Anthony L. Nguy-Robertson, Arthur Zygielbaum, Anthony J. Mcmechan, Gary L. Hein, Stephen N. Wegulo, Abby R. Stilwell, Travis M. Smith
Developing The Framework For A Risk Map For Mite Vectored Viruses In Wheat Resulting From Pre-Harvest Hail Damage, Anthony L. Nguy-Robertson, Arthur Zygielbaum, Anthony J. Mcmechan, Gary L. Hein, Stephen N. Wegulo, Abby R. Stilwell, Travis M. Smith
Department of Plant Pathology: Faculty Publications
There is a strong economic incentive to reduce mite-vectored virus outbreaks. Most outbreaks in the central High Plains of the United States occur in the presence of volunteer wheat that emerges before harvest as a result of hail storms. This study provides a conceptual framework for developing a risk map for wheat diseases caused by mite-vectored viruses based on pre-harvest hail events. Traditional methods that use NDVI were found to be unsuitable due to low chlorophyll content in wheat at harvest. Site-level hyperspectral reflectance from mechanically hailed wheat showed increased canopy albedo. Therefore, any increase in NIR combined with large …
Coherent Late-Holocene Climate-Driven Shifts In The Structure Of Three Rocky Mountain Lakes, Jeffrey R. Stone, Jasmine E. Saros, Gregory T. Pederson
Coherent Late-Holocene Climate-Driven Shifts In The Structure Of Three Rocky Mountain Lakes, Jeffrey R. Stone, Jasmine E. Saros, Gregory T. Pederson
United States Geological Survey: Staff Publications
Large-scale atmospheric pressure centers, such as the Aleutian and Icelandic Low, have a demonstrated relationship with physical lake characteristics in contemporary monitoring studies, but the responses to these phenomena are rarely observed in lake records. We observe coherent changes in the stratification patterns of three deep (>30 m) lakes inferred from fossil diatom assemblages as a response to shifts in the location and intensity of the Aleutian Low and compare these changes with similar long-term changes observed in the 18O record from the Yukon. Specifically, these records indicate that between 3.2 and 1.4 ka, the Aleutian Low shifted …
Using Satellite Vegetation And Compound Topographic Indices To Maphighly Erodible Cropland Buffers For Cellulosic Biofuel Cropdevelopments In Eastern Nebraska, Usa, Yingxin Gu, Bruce K. Wylie
Using Satellite Vegetation And Compound Topographic Indices To Maphighly Erodible Cropland Buffers For Cellulosic Biofuel Cropdevelopments In Eastern Nebraska, Usa, Yingxin Gu, Bruce K. Wylie
United States Geological Survey: Staff Publications
Cultivating annual row crops in high topographic relief waterway buffers has negative environmental effects and can be environmentally unsustainable. Growing perennial grasses such as switchgrass(Panicum virgatum L.) for biomass (e.g., cellulosic biofuel feedstocks) instead of annual row crops in these high relief waterway buffers can improve local environmental conditions (e.g., reduce soil erosion and improve water quality through lower use of fertilizers and pesticides) and ecosystem services (e.g.,minimize drought and flood impacts on production; improve wildlife habitat, plant vigor, and nitro-gen retention due to post-senescence harvest for cellulosic biofuels; and serve as carbon sinks). The main objectives of this …
Evaluating Methods To Establish Habitat Suitability Criteria: A Case Study In The Upper Delaware River Basin, Usa, H. S. Galbraith, C. J. Blakeslee, J. C. Cole, C. A. Talbert, K. O. Maloney
Evaluating Methods To Establish Habitat Suitability Criteria: A Case Study In The Upper Delaware River Basin, Usa, H. S. Galbraith, C. J. Blakeslee, J. C. Cole, C. A. Talbert, K. O. Maloney
United States Geological Survey: Staff Publications
Defining habitat suitability criteria (HSC) of aquatic biota can be a key component to environmental flow science. HSC can be developed through numerous methods; however, few studies have evaluated the consistency of HSC developed by different methodologies. We directly compared HSC for depth and velocity developed by the Delphi method (expert opinion) and by two primary literature meta-analyses (literature- derived range and interquartile range) to assess whether these independent methods produce analogous criteria for multiple species (rainbow trout, brown trout, American shad, and shallow fast guild) and life stages. We further evaluated how these two independently developed HSC affect calculations …
Evaluating Land Cover Influences On Model Uncertainties—A Case Study Of Cropland Carbon Dynamics In The Mid-Continent Intensive Campaign Region, Zhengpeng Li, Shuguang Liu, Xuesong Zhang, Tristram O. West, Stephen M. Ogle, Naijun Zhou
Evaluating Land Cover Influences On Model Uncertainties—A Case Study Of Cropland Carbon Dynamics In The Mid-Continent Intensive Campaign Region, Zhengpeng Li, Shuguang Liu, Xuesong Zhang, Tristram O. West, Stephen M. Ogle, Naijun Zhou
United States Geological Survey: Staff Publications
tQuantifying spatial and temporal patterns of carbon sources and sinks and their uncertainties acrossagriculture-dominated areas remains challenging for understanding regional carbon cycles. Character-istics of local land cover inputs could impact the regional carbon estimates but the effect has not beenfully evaluated in the past. Within the North American Carbon Program Mid-Continent Intensive (MCI)Campaign, three models were developed to estimate carbon fluxes on croplands: an inventory-basedmodel, the Environmental Policy Integrated Climate (EPIC) model, and the General Ensemble biogeo-chemical Modeling System (GEMS) model. They all provided estimates of three major carbon fluxes oncropland: net primary production (NPP), net ecosystem production (NEP), and …
Patuxent’S American Black Duck Studies From Chesapeake Bay To Maine And Beyond, Jerry R. Longcore
Patuxent’S American Black Duck Studies From Chesapeake Bay To Maine And Beyond, Jerry R. Longcore
United States Geological Survey: Staff Publications
The information in this chapter draws on published literature and unpublished reports written by staff members of the U.S. Geological Survey, Patuxent Wildlife Research Center (Patuxent), during its 75-year history. Reports by Bureau of Biological Survey (Biological Survey) and U.S. Fish and Wildlife Service (USFWS) personnel are included because the research entity currently known as Patuxent was formerly administered by these agencies. Some of the cited reports were prepared by USFWS scientists while they were not working at Patuxent. Literature resulting from work at other Federal and State agencies and private and academic institutions that influenced research at Patuxent on …
Amino Acid Specific Stable Nitrogen Isotope Values In Avian Tissues: Insights From Captive American Kestrels And Wild Herring Gulls, C.E. Hebert, B.N. Popp, K.J. Fernie, C. Ka’Apu-Lyons, B.A. Rattner, N. Wallsgrove
Amino Acid Specific Stable Nitrogen Isotope Values In Avian Tissues: Insights From Captive American Kestrels And Wild Herring Gulls, C.E. Hebert, B.N. Popp, K.J. Fernie, C. Ka’Apu-Lyons, B.A. Rattner, N. Wallsgrove
United States Geological Survey: Staff Publications
Through laboratory and field studies, the utility of amino acid compound-specific nitrogen isotope analysis (AA-CSIA) in avian studies is investigated. Captive American kestrels (Falco sparverius) were fed an isotopically characterized diet and patterns in δ15N values of amino acids (AAs) were compared to those in their tissues (muscle and red blood cells) and food. Based upon nitrogen isotope discrimination between diet and kestrel tissues, AAs could mostly be categorized as source AAs (retaining baseline δ15N values) and trophic AAs (showing 15N enrichment). Trophic discrimination factors based upon the source (phenylalanine, Phe) and trophic (glutamic acid, Glu) AAs were 4.1 (muscle) …
Non-Linear Responses Of Glaciated Prairie Wetlands To Climate Warming, W. Carter Johnson, Brett Werner, Glenn R. Guntenspergen
Non-Linear Responses Of Glaciated Prairie Wetlands To Climate Warming, W. Carter Johnson, Brett Werner, Glenn R. Guntenspergen
United States Geological Survey: Staff Publications
The response of ecosystems to climate warming is likely to include threshold events when small changes in key environmental drivers produce large changes in an ecosystem. Wetlands of the Prairie Pothole Region (PPR) are especially sensitive to climate variability, yet the possibility that functional changes may occur more rapidly with warming than expected has not been examined or modeled. The productivity and biodiversity of these wetlands are strongly controlled by the speed and completeness of a vegetation cover cycle driven by the wet and dry extremes of climate. Two thresholds involving duration and depth of standing water must be exceeded …
Pranked By Audubon: Constantine S. Rafinesque’S Description Of John James Audubon’S Imaginary Kentucky Mammals, Neal Woodman
Pranked By Audubon: Constantine S. Rafinesque’S Description Of John James Audubon’S Imaginary Kentucky Mammals, Neal Woodman
United States Geological Survey: Staff Publications
The North American naturalist Constantine S. Rafinesque spent much of the year 1818 engaged in a solo journey down the Ohio River Valley to explore parts of what was then the western United States. Along the way, he visited a number of fellow naturalists, and he spent more than a week at the Henderson, Kentucky, home of artist and ornithologist John James Audubon. During the succeeding two years, Rafinesque published descriptions of new species that resulted from his expedition, including eleven species of fishes that eventually proved to have been invented by Audubon as a prank on the credulous naturalist. …
Non-Linear Responses Of Glaciated Prairie Wetlands To Climate Warming, W. Carter Johnson, Brett Werner, Glenn R. Guntenspergen
Non-Linear Responses Of Glaciated Prairie Wetlands To Climate Warming, W. Carter Johnson, Brett Werner, Glenn R. Guntenspergen
United States Geological Survey: Staff Publications
The response of ecosystems to climate warming is likely to include threshold events when small changes in key environmental drivers produce large changes in an ecosystem. Wetlands of the Prairie Pothole Region (PPR) are especially sensitive to climate variability, yet the possibility that functional changes may occur more rapidly with warming than expected has not been examined or modeled. The productivity and biodiversity of these wetlands are strongly controlled by the speed and completeness of a vegetation cover cycle driven by the wet and dry extremes of climate. Two thresholds involving duration and depth of standing water must be exceeded …
Seasonal Evolution Of Active Layer Formation In Subarctic Peat Plateaux And Implications For Dissolved Organic Matter Composition And Transfer, Jennifer L. Hickman
Seasonal Evolution Of Active Layer Formation In Subarctic Peat Plateaux And Implications For Dissolved Organic Matter Composition And Transfer, Jennifer L. Hickman
Theses and Dissertations (Comprehensive)
Peat-accumulating wetlands are ecosystems whose rate of photosynthetic production of organic matter is greater than that of its decomposition, resulting in a build up of soil organic matter that may take centuries to fully decompose. Carbon (C) stocks within these ecosystems are a function of inputs from photosynthesis, and losses from heterotrophic decomposition. Due to the short growing season and overall cold climate of boreal and tundra regions, C has been accumulating within these landscapes, mostly in soil organic matter, since the last glaciation. Climate change, predicted to result in rising temperatures and increased precipitation, has begun to degrade the …
Partitioning Evapotranspiration In Forested Peatlands Within The Western Boreal Plain, Fort Mcmurray, Alberta, Canada, Elise C. Gabrielli
Partitioning Evapotranspiration In Forested Peatlands Within The Western Boreal Plain, Fort Mcmurray, Alberta, Canada, Elise C. Gabrielli
Theses and Dissertations (Comprehensive)
Forested peatlands in the Western Boreal Plain (WBP) represent hydrologically sensitive ecosystems that often support an open-crown forest of Picea mariana and/or Larix laricina. These systems store globally significant soil carbon, containing one-fourth to one-third of the world’s soil organic carbon pool (Turunen et al., 2002),serving a critical role in regulating atmospheric CO2. Recent studies indicate that the hydrological conditions are the critical determinant of a peatland’s carbon budget (Price et al., 2005; Aurela et al., 2007).To understand current hydrological conditions, it is essential to accurately estimate the rate of ET, due …
Adsorption Of Antibiotics By Vermiculite, Mosa J. Ferdous
Adsorption Of Antibiotics By Vermiculite, Mosa J. Ferdous
Dissertations and Theses
The occurrence of residual antibiotics in the environment has been a worldwide issue and warrants the development of inexpensive yet effective methods for antibiotics removal from contaminated water. In this thesis work, the adsorption of four antibiotics, namely chlorotetracycline (CTC), oxytetracycline (OTC), ofloxacin (OFL), and enrofloxacin (ENR), onto natural vermiculite has been studied using batch (static) and column (dynamic) adsorption techniques. The Langmuir and Freundlich isotherm models were initially used to explain the adsorption processes. The separation factor (RL) values derived from the Langmuir model and the 1/n values derived from Freundlich model in the present investigation were less than …
Modern Foraminiferal Assemblages Of The Denmark Strait, Laura Larocca
Modern Foraminiferal Assemblages Of The Denmark Strait, Laura Larocca
Dissertations and Theses
Foraminifera occupy a geological range from the early Cambrian to the present day. Their well preserved shells, high relative abundance, and short response time to changing environmental conditions make foraminifera ideal proxies for environmental change. Benthic foraminifera are a valuable but poorly understood paleobiological proxy for the reconstruction of environmental conditions on continental shelves occupied by arctic and subarctic waters. This study identifies, examines, and quantifies calcareous benthic foraminiferal faunas from a sediment core taken from the Denmark Strait. Our analysis of three-thousand individuals from ten discrete samples aim to provide a better understanding of the modern patterns of foraminiferal …
Analyzing Evapotranspiration In The Tropical Montane Cloud Forest At Sierra De Bahoruco, Dominican Republic, Emmanuel Rodriguez-Gonzalez
Analyzing Evapotranspiration In The Tropical Montane Cloud Forest At Sierra De Bahoruco, Dominican Republic, Emmanuel Rodriguez-Gonzalez
Dissertations and Theses
Lake Enriquillo is located in the southwestern extreme of Dominican Republic and has been experiencing a rapid expansion in surface area, along with other water bodies in the same region, since 2004 causing major flooding to the surrounding agricultural and cattle-raising lands, infrastructure and communities. Understanding why the lake is expanding at such rapid rate and accurately forecast how they will behave in the future is the main goal of The Hispaniola Lakes Project. The purpose of this project is to investigate the effects that hydrometeorological drivers are having on the forested areas located in Sierra de Bahoruco, which is …
3d Structural And Stratigraphic Architecture Of The Northwest Santa Barbara Basin And Implications For Submarine Landslide Generation, Alexis Wright
3d Structural And Stratigraphic Architecture Of The Northwest Santa Barbara Basin And Implications For Submarine Landslide Generation, Alexis Wright
Dissertations and Theses
Multiple submarine landslides have been previously documented on the north flank of the Santa Barbara Channel, and such failures are considered to be capable of generating local tsunamis hazards to the Santa Barbara region. 2D seismic-reflection datasets provide a general view of regional framework geology, including faulting and folding associated with north-south compression. However, better understanding of the relationships between faults, folds, stratigraphic architecture, and submarine landslides can be obtained with 3D seismic datasets. In this study we use an industry 3D seismic-reflection volume that encompasses the slope and shelfbreak surrounding the Gaviota submarine landslide (3.8 km2) to investigate structural …
Assessing The Utility Of Imaging Radar For Identifying White Sand Vegetation Structure, Jessica Rosenqvist
Assessing The Utility Of Imaging Radar For Identifying White Sand Vegetation Structure, Jessica Rosenqvist
Dissertations and Theses
White sand vegetation communities are wide spread across South America; found in Peru, Venezuela, Brazilian Amazon and Guyana. They are distributed in patches ranging from <1 km2 to greater than tens of square kilometers and their origins and locations are still not well understood. The communities are related to a variety of factors (soil type, flooding, nutrient content and fire); hence a precise definition for the ecosystem is still not fully defined. Nevertheless, the result of these variations creates a unique environment for endemic plant and animal species to thrive. Furthermore, analysis of these areas has been very scattered and identification of local white sand areas (<1 km2) have not been accomplished. In addition, identification of these locations has currently only used optical satellite imagery (Landsat, MODIS). Hence, in this project, we have attempted to use synthetic aperture radar to create a classification system to locate the white sand vegetation systems. The goal is to be able to apply this method to identify white sand vegetation distribution across South America. The region of focus for this thesis has been in Aracá, a large white sand area located in Brazil in the State of Amazonas. Due to the lack of ground reference data, a classified map by Capurucho et al. (2013), generated using Landsat data, was used as a comparison and reference. JAXA’s ALOS-1 PALSAR (L-band), ESA’s Sentinel-1A (C-band) and NASA’s SRTM sensors were used for land classification. As microwave signals penetrate clouds and haze, the advantage of using sensors with this wavelength allows for an unobstructed coverage of the landscape all year round. Different combinations of polarizations and wavelengths were used during the analysis to try and separate the white sand vegetation from water and terra firme forest. The resulting classification images showed a 30% agreement with the classification map by Capurucho et al. It is important to note, that this number is in fact an agreement percentage as the map used was a classification image and coarse in resolution (due to the lack of reference data). Therefore, this value does not imply a bad classification. Future work will include time-series data, precise ground reference points and data from other sensors such as ALOS-2 PALSAR, to improve the classification accuracy.
Evidence For The Drainage Of A Superglacial Lake As The Source Of Seismic Waves Recorded At A Regional Distance, Erik J. Orantes
Evidence For The Drainage Of A Superglacial Lake As The Source Of Seismic Waves Recorded At A Regional Distance, Erik J. Orantes
Dissertations and Theses
Surface melting during the summer leads to the formation of lakes on the Greenland Ice Sheet surface, known as supraglacial lakes. Some of these lakes drain through cracks in their beds and release the water into the ice sheet. Previous studies suggest that some of the water reaches the bedrock, enabling basal sliding, which could potentially increase glacial discharge (Sundal et al., 2009). Das et al. (2008) showed that supraglacial lake drainage can be accompanied by seismic activity, but little work has been done on the regional detection of such waves. The present study analyzes seismic data for the period …