Evidence For Static Stress Changes Triggering The 1999 Eruption Of Cerro Negro Volcano, Nicaragua And Regional Aftershock Sequences, 2011 University of South Florida
Evidence For Static Stress Changes Triggering The 1999 Eruption Of Cerro Negro Volcano, Nicaragua And Regional Aftershock Sequences, M. Diez, P. C. La Femina, Charles B. Connor, W. Strauch, Tenorio V. Tenorio
Remarkable evidence of coupling between tectonic and magmatic events emerges from investigation of three tectonic earthquakes, aftershock sequences and eruption of Cerro Negro volcano, Nicaragua in 1999. Here, we explain this coupling through static stress changes following three Mw 5.2 earthquakes. We use focal mechanism solutions to estimate fault system geometry and magnitude of slip from these events, which are then used to calculate the change in minimum horizontal principal stress (σ3) for the region and the change in Coulomb failure stress on optimally oriented fault planes. Results of these simulations indicate that σ3 was reduced by ∼0.08 ...
Exploring Links Between Physical And Probabilistic Models Of Volcanic Eruptions: The Soufriere Hills Volcano, Montserrat, 2011 University of South Florida
Exploring Links Between Physical And Probabilistic Models Of Volcanic Eruptions: The Soufriere Hills Volcano, Montserrat, Charles B. Connor, R. S. J. Sparks, R. M. Mason, Costanza Bonadonna, S. R. Young
Probabilistic methods play an increasingly important role in volcanic hazards forecasts. Here we show that a probability distribution characterized by competing processes provides an excellent statistical fit (>99% confidence) to repose intervals between 75 vulcanian explosions of Soufrière Hills Volcano, Montserrat in September–October, 1997. The excellent fit is explained by a physical model in which there are competing processes operating in the upper volcano conduit on different time scales: pressurization due to rheological stiffening and gas exsolution, and depressurization due to development of permeability and gas escape. Our experience with the Soufrière Hills Volcano eruption sequence suggests that volcanic ...
Modeling Long-Term Volcanic Hazards Through Bayesian Inference: An Example From The Tohoku Volcanic Arc, Japan, 2011 Tono Geoscience Center, Japan Nuclear Cycle Development Institute
Modeling Long-Term Volcanic Hazards Through Bayesian Inference: An Example From The Tohoku Volcanic Arc, Japan, Andrew J. Martin, Koji Umeda, Charles B. Connor, Jennifer N. Weller, Dapeng Zhao, Masaki Takahashi
The need to quantitatively estimate future locations of volcanoes in the long-term is of increasing importance, partly as a result of the requirement of constructing certain types of installations in regions of low geologic risk. The complex geological factors and natural processes controlling the locations of volcanoes make it problematic to estimate future patterns deterministically. Instead, the probabilistic approach can be developed with quite high levels of confidence; however, for regions with few or no volcanoes, there is a need to include additional geological and geophysical data that may indicate the likelihood of future volcanism. We achieve this using Bayesian ...
Probabilistic Modeling Of Tephra Dispersal: Hazard Assessment Of A Multiphase Rhyolitic Eruption At Tarawera, New Zealand, 2011 University of South Florida
Probabilistic Modeling Of Tephra Dispersal: Hazard Assessment Of A Multiphase Rhyolitic Eruption At Tarawera, New Zealand, Costanza Bonadonna, Charles B. Connor, B. F. Houghton, Laura Connor, Marc A. Byrne, A. Laing, T. K. Hincks
The Tarawera Volcanic Complex comprises 11 rhyolite domes formed during five major eruptions between 17,000 B.C. and A.D. 1886, the first four of which were predominantly rhyolitic. The only historical event erupted about 2 km3 of basaltic tephra fall (A.D. 1886). The youngest rhyolitic event erupted a tephra fall volume more than 2 times larger and covered a wider area northwest and southeast of the volcano (∼A.D. 1315 Kaharoa eruption). We have used the Kaharoa scenario to assess the tephra fall hazard from a future rhyolitic eruption at Tarawera of a similar scale. The ...
Modeling Tephra Sedimentation From A Ruapehu Weak Plume Eruption, 2011 University of South Florida
Modeling Tephra Sedimentation From A Ruapehu Weak Plume Eruption, Costanza Bonadonna, J. C. Phillips, B. F. Houghton
We present a two-dimensional model for sedimentation of well-mixed weak plumes, accounting for lateral spreading of the cloud, downwind advection, increase of volumetric flux in the rising stage, and particle transport during fallout. The 17 June 1996 subplinian eruption of Ruapehu produced a bent-over plume that rose to a height of 8.5 km in a wind field with an average velocity of 24 m s−1 and generated a narrow deposit on land extending up to 200 km from vent. The sedimentation from the Ruapehu plume was dominated by coarse ash, with all the blocks and most of the ...
Sedimentology And Age Constraints Of Pleistocene Outburst Flood-Related Deposits In The Palouse Hills, Southeastern Washington, Karen Gastineau
The well-documented late Wisconsinan Missoula Floods have recently been shown to be only the final sequence in a process that has been ongoing for at least the second half of the Pleistocene. An outcrop in southern Walla Walla County, Washington shows complex stratigraphic relationships, including potential flood-cut unconformities that suggest a history related to earlier catastrophic glacial outburst floods. The outcrop contains 11 distinct units defined by changes in composition, the presence of soils, toptruncated clastic dikes, clasts of exotic lithologies, and obvious unconformities. The basal unit is a two-meter thick, poorly consolidated quartz sand with large-scale cross-bedding indicating eolian ...
Cracking Up : Lithological Controls On Non-Tectonic Rock Cracks, Mojave Desert, California, Sarah G. Evans
Physical weathering affects erosion rates, sediment production, and atmospheric concentrations of CO2, yet non-tectonic-related crack formation is poorly understood. Thermal stresses related to diurnal directional insolation may play the primary role in generating cracks initially, but it is unknown how specific rock properties affect this process. In this study we utilized field data from the 130 ka Providence Mountain alluvial fans and the ~140 ka Cima Volcanic Field basalt flows in the Mojave Desert to determine if crack population characteristics vary as a function of lithology. We measured crack density and orientation for more than 400 rocks along 19 transects ...
Topographic Lineaments And Expression Of Fracture Arrays In The Edelman And North Paint Rock Creek Lineaments, Bighorn Mountains, Wyoming, Charles Cashman Trexler
The Bighorn Mountains of north central Wyoming are a basement-cored arch formed during the Laramide Orogeny. Working in association with the Bighorn Arch Seismic Experiment, the Keck Bighorns project seeks to understand the structures within the crystalline basement and sedimentary cover rocks during formation of the arch. Little is known of the origin of the brittle structures within the crystalline rocks at the core of the arch, and distinguishing Laramide-related faults and folds from Precambrian structures is not an easy task. Erosion of these structures has produced topographic lineaments throughout the range. Combined field measurements and GIS-based topographic lineament analysis ...
Variations In The Soil Properties Of The Premier Vineyards Of The Columbia Basin : Implications For Terroir, Erica M. Pitcavage
The Columbia River Basin of Washington is the second most productive wine region in the United States. Most Columbia Basin vineyards lie within the Columbia Valley and Columbia Gorge American Viticultural Areas (AVAs), which together include 46,862 km2 in Washington and north-central Oregon. Eight sub-AVAs have been recognized within the Columbia Valley AVA. These AVAs contain many soil types, which have implications for the terroir of the vineyards. Most soils in the Columbia Basin are derived from loess that overlies basaltic bedrock and Pleistocene Missoula Floods deposits. The influence of the underlying Miocene Columbia River Basalt bedrock on soil ...
Stream Erosion And Beach Deposition During The December 2007 Storm, Hood Canal, Washington, Elizabeth K. Phillips
A strong winter storm hit western Washington and Oregon in the first week of December 2007. An accumulation of snow was closely followed by high sustained winds with gusts up to 130 kph (80 mph), much warmer temperatures, and about 300 mm of rain, causing record flooding, substantial tree blowdown, and significant damage to roads and property. An example of the geomorphic effects is found in an area along Hood Canal just north of Dewatto Bay where abnormal discharges along high-gradient streams (12°-17°) in small drainage basins (0.073-0.259 km2 ) resulted in severe erosion and the deposition of ...
The Glaciofluvial Environment On Linnebreen, Spitsbergen, Svalbard, 2011 Whitman College
The Glaciofluvial Environment On Linnebreen, Spitsbergen, Svalbard, Simon L. Pendleton
Thesis characterizing the glaciofluvial environment of the Linnébreen glacier in Svalbard, Norway and subsequent effects on high Arctic lacustrine sediment deposition. Climate forcings on the glacier control sediment production from the glacier and therefore should be recorded likewise in the lake sediment profiles. By understanding the relationships between local climate and sediment flux, a better understanding and correlation between climate and deposited sediment can be established.
Mineralogy And Geochemistry Of The Bauxite Deposits (Cretaceous), Wilkinson County, Georgia., 2011 Georgia State University
Mineralogy And Geochemistry Of The Bauxite Deposits (Cretaceous), Wilkinson County, Georgia., Adebayo O. Ayorinde
Cretaceous bauxite deposits from Hall and Veneer mines, Wilkinson County, Georgia are composed of kaolinite, gibbsite, goethite, anatase, nordstrandite and bohemite. Quartz and micas are absent in the samples. The presence of boehmite and goethite are evidence of intense weathering forming the bauxite deposits. The extremely high values of the Chemical Index of Alteration (CIA) which is over 99, and the low values of the alkali metals and alkali earth metals, support an intense weathering origin for the bauxite deposit. There is evidence of deposition in the mines based on the presence of pisoids in the bauxite samples and the ...
Particle Size, Critical Shear Stress, And Benthic Invertebrate Distribution And Abundance In A Gravel-Bed River Of The Southern Appalachians, Helen Mayoral
To determine the relationship between the abundance and density of benthic invertebrates, and the critical shear stress of individual grain sizes, a reach along Smith Creek, was divided into ten 2m x 2m quadrants. Within each quadrant, five randomly selected clasts for each grain size ranging from 2.26 to 25.6 cm were cleaned for benthic invertebrates. Wolman pebble counts for each quadrant were also conducted and used to determine the critical Shields stress per grain size fraction from the model given by Wiberg and Smith (1987) that explicitly accounts for particle hiding/sheltering effects in mixed-bed rivers. Particle ...
Intensive Study Of Ambient Carbon Dioxide Variability In Urban Atlanta, 2011 Georgia State University
Intensive Study Of Ambient Carbon Dioxide Variability In Urban Atlanta, Brian L. Vann Mr.
Urban areas contain multiple sources and sinks of carbon dioxide, yet spatial and temporal information explaining its variability, diurnal patterns, and effects from human activity are limited. The city of Atlanta, due to conflicting air masses, geographic location, and population growth, is as an excellent location to study carbon dioxide concentrations across its urban landscape. Mobile measurements of ambient CO2 concentrations were obtained at 1.5m above ground level along a transect in winter 2010 within the perimeter of Atlanta. Analyses of winter 2010 CO2 variability at GSU’s stationary CO2 monitor was also explored. The results ...
The Formation History Of Layered Chondrules In Acfer-139 (Cr2), 2011 Western Kentucky University
The Formation History Of Layered Chondrules In Acfer-139 (Cr2), Matt Downen
Honors College Capstone Experience/Thesis Projects
Chondrules are spherical grains made of silicates and metal that represent some of the oldest materials our solar system. Acfer-139 (CR) is a carbonaceous chondrite with large multilayered chondrules. The multilayered chondrules are composed of a silicate core surrounded by alternating layers of silicates and metals. Serial sectioning was used to analyze the sample in three dimensions. EMPA and LA-ICP-MS were used to create elemental maps of Acfer-139 (CR2) and determine the geochemistry of different layers in each thick section cut. XRCMT was used to construct a 3-D model of a large multilayered chondrule named Ch-1 with concentric layers of ...
Evapotranspiration In The Riparian Zone Of The Lower Boise River With Implications For Groundwater Flow, 2011 Boise State University
Evapotranspiration In The Riparian Zone Of The Lower Boise River With Implications For Groundwater Flow, Brady Allen Johnson
Boise State University Theses and Dissertations
Riparian zones in semi-arid regions often exhibit high rates of evapotranspiration (ET) in spite of low soil moisture content due to vegetation that is able to withdraw water from shallow aquifers. This work better defines the relationship between ET and the saturated zone by comparing the observed water table drawdown to analytically modeled drawdown in fully penetrating wells of an unconfined aquifer in response to daily ET flux. ET at the Boise Hydrogeophysical Research Site or BHRS (a riparian zone in a temperate, semi arid environment) is calculated following the approach of Batra et al. (2006) but uses site (or ...
An Accurate Ray-Based Offset-To-Angle Transform From Normal Moveout Uncorrected Multicomponent Data In A Transversely Isotropic Medium With Vertical Symmetry Axis, P. K. Mukhopadhyay, Subhashis Mallick
Geology and Geophysics Faculty Publications
A new ray-based approach for converting multicomponent normal moveout uncorrected offset domain prestack seismic data into angles is presented. From any two-way zero-offset time sample and a given angle of incidence, the exact ray and a few neighboring rays that contribute to the given angle of incidence are traced through the medium to their corresponding source and receiver locations to compute their raypath lengths, traveltimes, and offsets. A polynomial then is fitted locally between these computed offsets and their corresponding traveltimes. Next the traveltimes for the actual offsets on data that lie within these traced rays are computed from this ...
Carbon And Sulfur Cycling In Early Paleozoic Oceans, 2011 University of Tennessee, Knoxville
Carbon And Sulfur Cycling In Early Paleozoic Oceans, Cara Kim Thompson
Here, I evaluate biospheric evolution during the Ordovician using high-resolution inorganic carbon and sulfur (carbonate-associated sulfate and pyrite) isotope profiles for Early Ordovician to early Late Ordovician strata from geographically distant sections in Western Newfoundland and the Argentine Precordillera. Additionally, I present new, high-resolution U-Pb ages for volcanic ash beds within strata of the Argentine Precordillera. Carbon isotope data record subdued variation that is typical of Early- to Middle Ordovician strata worldwide. By contrast, sulfur-isotopic compositions of carbonate-associated sulfate reveal a complex signal of short-term, rhythmic variation superimposed over a longer-term signal. This short-term, rhythmic variation occurs in all sections ...
Aerial Reconnaissance Of Stream Terraces And Landslides Within Bitterwater Creek Watershed In Kern County, California, 2011 California Polytechnic State University - San Luis Obispo
Aerial Reconnaissance Of Stream Terraces And Landslides Within Bitterwater Creek Watershed In Kern County, California, Zachary Smith
Natural Resources Management and Environmental Sciences
No abstract provided.
Remote Sensing Of Sediments And Volatiles On The Martian Surface And Terrestrial Analog Sites, 2011 University of Tennessee
Remote Sensing Of Sediments And Volatiles On The Martian Surface And Terrestrial Analog Sites, Craig James Hardgrove
The role of water and volatiles in the solar system is of critical interest in planetary science. Evidence for the past action of water or direct observation of water on a planetary body can indicate the potential to harbor life and is critical to human exploration of the solar system. We study two very different remote sensing techniques that address the issue of identifying water-related processes on the surface of other planetary bodies, and in particular, Mars. The first technique, combined thermal infrared and visible imaging, has been used extensively on Mars for determining the thermal inertia of surface materials ...