• Examining sources of primary production and bottom-up limitations in nearshore ecosystems of the northeast Pacific Ocean using fish based indicators

      Biela, Vanessa Rebeca von; Kruse, Gordon H.; Zimmerman, Christian E.; Okkonen, Stephen R.; Mueter, Franz J.; Black, Bryan A. (2015-05)
      Our ability to forecast the fate of ecosystems and species hinges on an understanding of how biological systems respond to their environment. In this dissertation, natural indicators of diet (stable isotopes) and production (otolith growth increment width) in two common fishes were used to investigate energy pathways and biophysical relationships in nearshore kelp forests spanning two large marine ecosystems with contrasting oceanography, the upwelling system of the California Current and the downwelling system of the Alaska Coastal Current. Stable isotope analysis indicated high proportions of kelp-derived carbon in two common predatory fish, pelagic-feeding Black Rockfish and benthic-feeding Kelp Greenling. Routinely using both kelp and phytoplankton energy channels reflects strong benthic-pelagic coupling in nearshore marine food webs and may confer food web resilience to perturbations in either energy channel. A network of annual otolith growth chronologies were used to test bottom-up limits of production for nearshore systems and later explore other possible correlates of production. Results of hypothesis tests were consistent with bottom-up forcing of nearshore marine ecosystems, with light and nutrients constraining primary production in pelagic food webs and temperature constraining benthic food webs. A separate exploratory analysis indicated that biophysical relationships were common with (1-2 years) and without time lags and suggested that differences in the abundance and quality of prey influenced the growth of fish through bottom-up processes. The findings from the separate exploratory analysis were generally consistent with findings from hypothesis testing. Lagged relationships were consistent with increasing higher nearshore prey abundance during warm conditions in the Alaska Coastal Current and during cool conditions in the California Current in both pelagic and benthic food webs. Relationships without time lags indicated that benthic prey quality increased during warm conditions in both current systems, while the quality of pelagic nearshore prey increased during cool conditions in the California Current and warm conditions in the Alaska Current. Overall, results of this dissertation demonstrate that kelp provides a source of energy to higher trophic level predators and that continued warming will likely have a negative influence at lower latitudes first (e.g., California Current), while production in higher latitudes (e.g., Gulf of Alaska) may initially increase.
    • Examining the advocacy coalition framework for insight into shale gas development in US and UK political systems

      Wolfley, Kathryn (2014-12)
      The project considers the Advocacy Coalition Framework from the discipline of policymaking which is used to examine contentious and politically complex policy issues, particularly in energy and environmental development and planning. Shale gas development in the United States has been noted for its dramatic economic and political effects, leading some countries to pursue development of their own shale resources. The United Kingdom's tentative steps into the industry have engendered efforts to understand American experiences and conceptualize how their own country may or may not accommodate such development. The project attempts to highlight the current or potential issues or benefits entering the discourse and extrapolate insights from the Advocacy Coalition Framework to enhance and inform shale gas development as a social issue in addition to existing as an economic or technological disruption. Thoughts on attitudes between disciplines tangent to shale gas development are also expressed.
    • Examining the feasibility of implementing a matrix model intensive outpatient program in a remote Alaskan setting

      Ponziano, Frank; Gifford, Valerie; Renes, Susan; McMorrow, Samantha (2015)
      Significance: The Matrix Model is possibly the only evidenced-based, intensive outpatient approach for addiction that has been shown to be effective at treating addiction. However, the model has not been evaluated for its effectiveness in remote Alaskan settings, such as Fairbanks, Alaska. Specific Aim: This study examined the feasibility of the Matrix Model compared to Treatment as Usual (TAU) in Fairbanks, Alaska. TAU is defined as any other outpatient substance abuse treatment (SAT) other than Matrix Model treatment program. The model's philosophy will be examined, and a method for determining its feasibility for implementation in Fairbanks, Alaska, will be outlined. This project will provide a method for an agency to examine their readiness and philosophical compatibility for the Matrix Model. This research intends to explore contextual variables, such as environment, culture, policy, participant barriers, funding, and organizational philosophy. Methods: This study has reviewed the literature regarding evidence-based, intensive outpatient programs, other treatment philosophies, and the contextual variables that affect program implementation in the literature. Moreover, this study provides an analysis of the Matrix Model versus TAU to help guide a Fairbanks agency considering Matrix Model Intensive Outpatient Program (IOP). IOP is a 12 to 16 week intensive outpatient SAT that meets for 9 or more hours per week that integrates individual, family, and group counseling along with weekly drugs screens. Implications: This project aims to contribute to the body of knowledge regarding the Matrix Models effectiveness compared to TAU in remote Alaskan settings.
    • Examining the role of sea ice and meteorology in Arctic boundary layer halogen chemistry

      Peterson, Peter Kevin; Simpson, William; Trainor, Thomas; Tape, Carl; Douglas, Thomas (2015-05)
      Given the ubiquitous nature of ice, chemistry taking place on ice surfaces has a substantial effect on the environment, particularly in the polar regions. The return of sunlight to the polar regions releases halogen radicals (e.g. Br, Cl and their oxides, e.g. BrO) generated from salts on ice surfaces. These radicals fundamentally alter the chemistry of the Arctic boundary layer through processes such as boundary-layer ozone depletion events and mercury deposition events. Current understanding of the chemical processes involved in Arctic halogen chemistry is inhibited by a lack of knowledge about the ice surfaces on which this chemistry is thought to take place, as well as the sparsity of long-term field observations of this chemistry and its effects. This dissertation addresses both needs through a combination of laboratory experiments and long-term field studies. First, we use X-ray absorption computed micro-tomography at the Advanced Photon Source to image brine distributions within laboratory grown mimics of sea-ice features. These experiments showed that when brine is introduced to ice via wicking of brine from a saline surface, the resulting brine distribution is heterogeneous, with brine existing in distinct regions within the sample, rather than evenly spreading over the sample surface. To examine the horizontal and vertical extent of halogen chemistry in the Arctic boundary layer, we conducted long-term measurements of BrO at Barrow, Alaska using Multiple-Axis Differential Optical Absorption Spectroscopy (MAX-DOAS). We developed a method to reduce these measurements to timeseries of near-surface and total column amounts of BrO. These measurements showed that the vertical distribution is highly variable, ranging from shallow layer events confined to the lowest 200 m, to distributed column events, which have lower mixing ratios of BrO, but are more distributed throughout approximately the lowest kilometer of the atmosphere. We find that the observed vertical distributions of BrO are influenced by atmospheric stability. We found minimal influence of wind speed on either lower-tropospheric bromine activation (LT-VCD) or the vertical distribution of BrO, while examination of seasonal trends and the temperature dependence of the vertical distribution support the finding that atmospheric stability affects the distribution of BrO. While shallow layer events have higher concentrations of halogens, distributed column events tend to have higher overall amounts of activation, implying that in situ near surface measurements may be insufficient to constrain the role of environmental parameters in the activation of halogens. Examination of multiple years of data at Barrow, Alaska shows that time spent in first year ice (FYI) areas is weakly linearly correlated (R=0.38) with the activation of BrO. However, examining annual averages of BrO shows that despite the non-linear relationship between time in FYI areas and BrO, time spent in FYI areas still influences the interannual variability of BrO.
    • Examples of program music in piano literature: storm, ocean, devil, ghosts

      Stavrianou, Eleni-Persefoni; Zilberkant, Eduard; Post, William; Celaire, Jaunelle (2016-05)
      The purpose of this paper is to present background information on the author's graduate piano recital program, namely extended program notes on the music performed. It should be mentioned that, although not intended, the whole recital is, in a way or another, program music. It is divided in two parts: the first is about Storms and Water (with "The Tempest" by Beethoven and Une barque sur l' ocean by Ravel), and the second about Spirits (with Faust Waltz by Liszt and the Three Ghost Rags by William Bolcom). Alborada del gracioso by Ravel falls somehow in between these two parts - a gracioso (jester) is a character, thus a spirit; an entertaining one. In this paper, I will attempt to explain what inspired composers to add titles to their music - this extramusical aspect has always been very intriguing to me. In the case of Beethoven, the title was most probably given by someone else, therefore the "Tempest" is not intended to be programmatic. In the case of Liszt, the piece is a transcription of an opera, which can be considered a programmatic genre. Ravel's and Bolcom's compositions are undoubtedly program music, since the composers gave them descriptive titles and were inspired certainly by extramusical factors.
    • Exchange and interaction in western Aleutian prehistory: the efficacy of geochemical analysis of lithic raw material procurement on Amchitka Island

      Jew, Nicholas P.; Odess, Daniel; Gray, Patty; Severin, Kenneth (2007-05)
      There are two main objectives of this thesis; the first is to evaluate the efficacy of geochemical techniques for the identification of lithic raw materials used to make stone tools in the Aleutian Islands. The second objective is to use the data set acquired from the analytical methods to generate hypotheses pertaining to exchange and interaction on Amchitka Island. Looking at Amchitka's geology using x-ray fluorescence will provide the basis for examining the elemental characterization for identification of basalt materials. From this analysis, I compared the elemental concentration of basalt artifacts between six archaeological sites found on Amchitka. Through the use of principal components analysis, the basalt artifacts were chemically matched with those specimens containing similar elemental properties to determine if they derived from the same geologic sources on Amchitka. The generation of hypotheses was directed towards identifying potential basalt sources locations on Amchitka Island and archaeological sites which may be appropriate candidates for further investigations of exchange and interaction.
    • The exchange of water between Prince William Sound and the Gulf of Alaska

      Schmidt, George Michael (1977-05)
      Prince William Sound is a complex fjord-type estuarine system bordering the northern Gulf of Alaska. This study is an analysis of exchange between Prince William Sound and the Gulf of Alaska. Warm, high salinity deep water appears outside the Sound during summer and early autumn. Exchange between this ocean water and fjord water is a combination of deep and intermediate advective intrusions plus deep diffusive mixing. Intermediate exchange appears to be an annual phenomenon occurring throughout the summer. During this season, medium scale parcels of ocean water centered on temperature and NO maxima appear in the intermediate depth fjord water. Deep advective exchange also occurs as a regular annual event through the late summer and early autumn. Deep diffusive exchange probably occurs throughout the year, being more evident during the winter in the absence of advective intrusions.
    • Excitation of the ionized nitrogen molecule in the aurora

      Nielsen, Kim (2002-12)
      An understanding of the excitation mechanism of the ionospheric molecules during auroral activity is of vital importance for the overall ionospheric understanding including its interaction with the magnetosphere. In this thesis we study two emissions originating from the excited nitrogen molecule ion. The first negative (0,1) emission at 4278 Å originating from the B state, and Meinel (2,0) emission at 7852 Å originating from the A state during moderate to strong aurora have been observed with an imaging spectrograph at Poker Flat, Alaska. The B state has a short lifetime compared to the inverse collision frequency at auroral altitudes, while the A state can be deactivated during collisions at altitudes near 95 km. The B state can be populated by an up-welling of N₂ into sunlit regions. Both processes are expected to depend on auroral activity. If none of the processes are present we expect a constant ratio between the two emissions. Data for three nights have been studied and a constant ratio was found at all times. Thus neither deactivation of the A state or up-welling of the ion seem to appear during the observations presented here. The values of the ratio for the three nights are 2.53 plus-minus 0.38, 3.05 plus minus 0.22, and 3.40 plus minus 1.10, respectively.
    • Exhaust thimble for arctic environments

      Evans, Mark P.; Peterson, Rorik; Kim, Sun woo; Lin, Chuen-Sen (2016-05)
    • An existence theorem for solutions to a model problem with Yamabe-positive metric for conformal parameterizations of the Einstein constraint equations

      Knowles, Tyler D.; Maxwell, David; Rhodes, John A.; Rybkin, Alexei (2016-08)
      We use the conformal method to investigate solutions of the vacuum Einstein constraint equations on a manifold with a Yamabe-positive metric. To do so, we develop a model problem with symmetric data on Sn⁻¹ x S¹. We specialize the model problem to a two-parameter family of conformal data, and find that no solutions exist when the transverse-traceless tensor is identically zero. When the transverse traceless tensor is nonzero, we observe an existence theorem in both the near-constant mean curvature and far-from-constant mean curvature regimes.
    • Expectation maximization and latent class models

      Banos, Hector; Allman, Elizabeth; Faudree, Jill; Barry, Ron; Bueler, Edward (2016-05)
      Latent tree models are tree structured graphical models where some random variables are observable while others are latent. These models are used to model data in many areas, such as bioinformatics, phylogenetics, computer vision among others. This work contains some background on latent tree models and algebraic geometry with the goal of estimating the volume of the latent tree model known as the 3-leaf model M₂ (where the root is a hidden variable with 2 states, and is the parent of three observable variables with 2 states) in the probability simplex Δ₇, and to estimate the volume of the latent tree model known as the 3-leaf model M₃ (where the root is a hidden variable with 3 states, and is the parent of two observable variables with 3 states and one observable variable with 2 states) in the probability simplex Δ₁₇. For the model M₃, we estimate that the rough percentage of distributions that arise from stochastic parameters is 0:015%, the rough percentage of distributions that arise from real parameters is 64:742% and the rough percentage of distributions that arise from complex parameters is 35:206%. We will also discuss the algebraic boundary of these models and we observe the behavior of the estimates of the Expectation Maximization algorithm (EM algorithm), an iterative method typically used to try to find a maximum likelihood estimator.
    • Experiment Vs Nature: Using Amphiboles To Test Models Of Magma Storage And Pre-Eruptive Magma Dynamics Preceding The 2006 Eruption Of Augustine Volcano, Alaska

      Henton, Sarah Massey; Larsen, Jessica; Coombs, Michelle; Freymueller, Jeff; Izbekov, Pavel; Severin, Ken (2013)
      This study investigates magmatic conditions preceding the 2006 eruption of Augustine Volcano through the use of amphibole compositions and textures. Due to their restricted stability region and common occurrence in calc-alkaline magmas, amphiboles are important for investigating pre-eruptive magmatic conditions at subduction zone volcanoes. Chapter 1 presents a study into geochemical and textural variations of natural amphibole phenocrysts in the erupted magmas. Magnesiohornblendes in the high- and low-silica andesites exhibit limited compositional variability. Intermediate-silica andesites and quenched mafic enclaves contain amphiboles that vary in composition and classification (magnesiohornblende-magnesiohastinsitetschermakite). Compositional variations are controlled by temperature-dependent substitutions. Both high-and low-silica andesites represent magmas that were stored in the shallow crust at 4-8 km depth, remaining distinct due to a complex sub-surface plumbing system. Intermediate-silica andesites and quenched mafic inclusions represent newly formed hybrids of resident high- and low-silica andesite magmas and an intruding basalt. Chapter 2 presents the results of a phase equilibria study the refines the model for high-silica andesite storage. The natural phase assemblage was reproduced between 860-880�C and 120-200 MPa. Experimental plagioclase and groundmass glass compositions most closely replicate natural samples at ~130-140 MPa. Estimated storage conditions fall within the ranges suggested by natural petrological data and modeled storage depths from geodetic data. The high temperature stability of experimental quartz and biotite (not identified in natural samples) may reflect the high f<math> <f> <hsp sp="0.167"><inf>0<inf>2</inf></inf></f> </math>of the Augustine system as well as the rapid kinetics associated with the crystal-poor sintered starting material of some experiments. Chapter 3 presents results of the first experimental study to target heating-induced amphibole reaction rim formation. Experiments show that reaction rims form on remarkably short timescales. They share mineralogical and textural features with natural reaction rims previously thought to represent decompression processes. Reaction rims cannot be simply classified on the basis of semi-quantitative observations. Rather, in-depth data collection (e.g. X-rap mapping), and the calculation of kinetic parameters (e.g. crystal nucleation rates), is necessary. Chapter 4 presents a new MATLABRTM based program that performs mineral formula recalculations and the associated propagation of analytical uncertainty.
    • Experimental and computational studies of nanofluids

      Vajjha, Ravikanth S.; Das, Debendra K.; Lin, Chuen-Sen; Chukwu, Godwin A.; Shur, Yuri (2014-12)
      The goals of this dissertation were (i) to experimentally investigate the fluid dynamic and heat transfer performance of nanofluids in a circular tube, (ii) to study the influence of temperature and particle volumetric concentration of nanofluids on thermophysical properties, heat transfer and pumping power, (iii) to measure the rheological properties of various nanofluids and (iv) to investigate using a computational fluid dynamic (CFD) technique the performance of nanofluids in the flat tube of a radiator. Nanofluids are a new class of fluids prepared by dispersing nanoparticles with average sizes of less than 100 nm in traditional heat transfer fluids such as water, oil, ethylene glycol and propylene glycol. In cold regions of the world, the choice of base fluid for heat transfer applications is an ethylene glycol or propylene glycol mixed with water in different proportions. In the present research, a 60% ethylene glycol (EG) or propylene glycol (PG) and 40% water (W) by mass fluid mixture (60:40 EG/W or 60:40 PG/W) was used as a base fluid, which provides freeze protection to a very low level of temperature. Experiments were conducted to measure the convective heat transfer coefficient and pressure loss of nanofluids flowing in a circular tube in the fully developed turbulent regime. The experimental measurements were carried out for aluminum oxide (Al₂O₃), copper oxide (CuO) and silicon dioxide (SiO₂) nanoparticles dispersed in 60:40 EG/W base fluid. Experiments revealed that the heat transfer coefficient of nanofluids showed an increase with the particle volumetric concentration. Pressure loss was also observed to increase with the nanoparticle volumetric concentration. New correlations for the Nusselt number and the friction factor were developed. The effects of temperature and particle volumetric concentration on different thermophysical properties (e.g. viscosity, thermal conductivity, specific heat and density) and subsequently on the Prandtl number, Reynolds number and Nusselt number of three nanofluids were investigated. The three nanofluids studied were Al₂O₃, CuO and SiO₂ nanoparticles dispersed in a base fluid of 60:40 EG/W. Results showed that the Prandtl number of nanofluids increased with increasing particle volumetric concentration and decreased with an increase in the temperature. The Reynolds number of nanofluids for a specified geometry and velocity increased with an increase in temperature and decreased with an increase in particle volumetric concentration. The Mouromtseff numbers of nanofluids were higher than those of the conventional fluids under both laminar and turbulent flow conditions, proving the superiority of nanofluids in electronic cooling applications. Experiments were performed to investigate the rheological properties of various nanoparticles dispersed in a 60:40 PG/W base fluid. The nanoparticles studied were; Al₂O₃, CuO, SiO₂, zinc oxide (ZnO), titanium oxide (TiO₂) with particle diameters ranging from 15 to 75 nm and particle volumetric concentrations of up to 6%. All the nanofluids exhibited a non-Newtonian Bingham plastic behavior at the lower temperature range of 243 K to 273 K and a Newtonian behavior in the temperature range of 273 K to 363 K. A new correlation was developed for the viscosity of nanofluids as a function of temperature, particle volumetric concentration, particle diameter, the properties of nanoparticles and those of the base fluid. Measurements were also conducted for single wall, bamboo-like structured and hollow structured multi-wall carbon nanotubes dispersed in a base fluid of 20:80 PG/W. A low-volume concentration (0.229%) of these carbon nanotubes (CNT) nanofluids revealed a non-Newtonian behavior over a measured temperature range of 273 K to 363 K. From the experimental data, a new correlation was developed which related viscosity to temperature and the Péclet number for CNT nanofluids. A three-dimensional CFD study was performed to analyze the heat transfer and fluid dynamic performance of nanofluids flowing in the turbulent regime in a flat tube of an automotive radiator. Computations were carried out for the Al₂O₃ and CuO nanoparticles of 0 to 6% particle volumetric concentrations dispersed in a base fluid of 60:40 EG/W. The numerical study revealed that under equal pumping power basis, the Al₂O₃ and CuO nanofluids up to 3% and 2% particle volumetric concentrations respectively, provided higher heat transfer coefficients than those provided by the base fluid. From this study, several new correlations to determine the Nusselt number and friction factor for the nanofluids flowing in the flat tubes of a radiator were developed for the entrance as well as the fully developed regions.
    • Experimental and economic evaluation of GTL fluid flow properties and effect on TAPS

      Ramakrishnan, Hariharan (2000-12)
      In this study, procedures are outlined to recondition and sample crude oil from high-pressure Welker cylinders. Standard laboratory procedures are developed to determine viscosity and density properties of crude oil, GTL and their mixtures. The steps needed to ensure Quality Assurance and Project Plan (QAPjp) is given in detail. A calibration macro is written to automate viscometer calibration calculations. A preliminary economic model is developed to evaluate GTL transportation options. Viscosity and density are measured for various samples at different temperatures. The reproducibility of the results is found to be within 5%. Batching is more preferable then blending for the parameter values considered in the economic model. In brief, GTL option appears to be a feasible way of utilizing Alaskan North Slope (ANS) gas resources and increasing the lifetime of TAPS, if suitable advancement in GTL conversion technology results in a substantial reduction in capital investment.
    • Experimental and numerical fluid flow analysis of an intersecting channel flow-field for proton exchange membrane fuel cell applications

      Gudimetla, Venkata A.; Witmer, Dennis E.; Misra, Debasmita; Lin, Chuen-Sen (2006-12)
      The present work aims to analyze the geometry of a new flow-field plate called the intersecting channel flow-field, developed at the University of Alaska Fairbanks (UAF). Four different two-dimensional models have been investigated and analyzed for the uniform spatial mass flow distribution of air in the channels. Based on the outcome of the two-dimensional models, a three-dimensional model of the flow-field was analyzed using CFD and the results were compared with those from an experiment which was conducted at UAF. The results from the three-dimensional numerical analysis showed a minor deviation from the experimental results.
    • Experimental and numerical simulation of hydraulic fracturing

      Hoveidafar, Mohammad; Chen, Gang; Metz, Paul; Ahn, Il Sang; Zhang, Yin (2017-12)
      Hydraulic Fracturing (HF) has many applications in different fields such as stimulation of oil and gas reservoirs, in situ stress measurements, stress relief for tunneling projects as well as in underground mining applications such as block caving mining. In the HF process, high pressure fluid is injected into a well to generate fractures in tight rock formations. This technique is particularly suitable for developing hydrocarbon energy resources in tight rock formations such as shale with very low permeability. An experimental setup was designed and developed to simulate the HF process in the laboratory. Cubic plaster specimens were molded and HF experiments were conducted with simulated plaster models. Five laboratory tests were performed on cubic specimens under different stress conditions. Because the uniaxial compressive strength of the plaster was about 1600 psi, in all experiments the applied vertical stress was 1000 psi to avoid breaking the specimens before injection of fluid. The differential horizontal stress varied from 100 to 500 psi. These stress levels are related to shallow formations in a real environment. It was observed that increasing the differential horizontal stress by 100 psi, the minimum pressure required to initiate HF decreases about 100 psi. These results were in agreement by 2D failure criterion of HF. All in all, the small scale HF experiments were conducted successfully in the rock mechanics lab. It was observed that vertical hydraulic fractures would propagate along maximum horizontal stress, which is in agreement with propagation of HF theory. Three-dimensional (3D) numerical models were developed and computer simulations were conducted with ABAQUS, a commercially available finite element analysis (FEA) software. The numerical simulation results compared favorably with those from the laboratory experiments, and verification and analysis were carried out. Since the results obtained from the numerical model were in agreement with the results of experiments and verified the correctness of the model, further investigation was carried out with developed computer models. Several scenarios with different vertical stresses and different levels of horizontal stress were simulated. A statistical software, R, was used to generate a 3D failure criterion for the HF in shallow formations.... It can be stated that in shallow formations, vertical stress has the least effect among stress components on the minimum pressure required to initiate HF.
    • Experimental And Numerical Study Of Sonic Wave Propagation In Freezing Sand And Silt

      Li, Hui (2009)
      A numerical model for delineating the temperature-velocity relationship of freezing porous media and soil is developed in Matlab based on Leclaire's Biot-type three-phase theory. Leclaire's theory gives lower sonic velocities than the experimental results because it does not take into consideration the effect of the solid-ice frame when water is freezing. To take the solid-ice effective frame into account, the average bulk and shear moduli estimation are modified with a proposed procedure. The modification gives higher P-wave and S-wave velocities that fit experimental data well. A comprehensive suite of physical and acoustic laboratory experiments are conducted on artificial sands, sand-clay mixtures and Fairbanks silts to investigate the temperature-velocity relationship during the freezing process and the effects of grain size and fine clay content. A Multi-channel ultrasonic scanning system (MUSS) is designed, installed and programmed for the experimental computerized ultrasonic tomography (CUST) study. The inward and outward freezing process and freezing front development in Fairbanks silt samples are observed using computerized ultrasonic tomography (CUST) in the laboratory. The experiments generate sonic wave velocity and temperature distribution during the freezing process. The freezing front is clearly identified in the CUST as a function of time and temperature. Comprehensive numerical finite element method (FEM) simulations, which account for the conduction in porous media, the latent heat effect and the nonlinear thermal properties of soil, are performed on the inward and outward freezing process of Fairbanks silt based on the experimental conditions. In conjunction with the temperature-velocity model developed in the study, sonic wave velocity tomograms are generated. The results are comparable with those obtained by CUST. The study indicates that CUST is an effective method for studying freezing processes and has potential for indirect measurement of unfrozen water content variations in the soil without interfering with the freezing process.
    • Experimental And Petrologic Constraints On Magma Movement, Storage, And Interactions At Two Volcanoes In Katmai National Park, Alaska

      Coombs, Michelle Lynn; Eichelberger, John C. (2001)
      Between 1953 and 1974, ~0.5 km3 of lava and tephra erupted from a new vent on the southwest flank of Trident volcano in Katmai National Park, Alaska, forming an edifice now known as Southwest Trident. The eruption commenced soon after mixing of dacite and andesite magmas at shallow crustal levels. The dacite lava flows contain andesitic enclaves as well as compositional banding. Dacite phenocryst melt inclusions and phase equilibria experiments on the andesite imply that the two magmas last resided at a water pressure of 90 MPa, and contained ~3.5 wt % H2O, equivalent to 3 km depth. Diffusion profiles in phenocrysts suggest that mixing preceded eruption of the earliest lava by approximately one month. The enclaves in the dacite had experienced a complex history by the time they were erupted. Quantitative analysis of groundmass microphenocrysts in enclaves from the lava shows that the enclaves underwent a textural maturation. I have run experiments that replicate the path taken by andesite during magma mixing in which the andesite was annealed at 1000�C, cooled at various rates to 890�C, held for residence time t, and then quenched. The andesite experimentally cooled at the slower rates (2�C/h and 10�C/h) most resembles enclave groundmass. This is consistent with cooling of the andesite below an andesite-dacite interface, suggesting that pre-enclave formation crystallization caused vapor exsolution and enclave flotation. Decompression experiments on the dacite suggest an average ascent time for the eruption of 30 hours. The high silica rhyolite erupted during the June 1912 eruption of Katmai is notable both for its large volume and evolved composition. Hydrothermal, water-saturated experiments constrain the magma's pre-eruptive storage condition to a region in P-T space between 800�C and 100 MPa and 850�C and 40 MPa. Amphibole is only present in the rhyolite of Novarupta dome, the last product of the eruption. Novarupta dome rhyolite probably was stored under the same conditions but underwent magma mixing with andesite and dacite prior to effusion.