Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 213 for “"eruptions"”.
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Theoretical mechanisms for solar eruptions
… thesis presents new theoretical models of solar eruptions which are derived from older models that involve a loss of equilibrium of the Sun's coronal magnetic field. These models consist of a magnetic flux rope nested within an arcade of magnetic loop. Prior to an eruption, the flux rope floats …
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Fracture mechanics of volcanic eruptions
… is a key tool in the forecasting of volcanic eruptions. The onset of an eruption is often preceded and accompanied by an increase in local seismic activity, driven by fracturing within the edifice. For closed systems, with a repose interval of the order of a century or more, this fracturing …
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Dynamics of ash eruptions at Vesuvius
… related to mid-low intensity, long lasting eruptions, has been increasingly described to occur at different volcanoes worldwide. Focusing on this type of deposits, a retrospective analysis of the stratigraphic successions at Vesuvius revealed that such type of eruptions have occurred …
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Dynamics of deep-submarine explosive eruptions
… findings of this study for submarine explosive eruptions and estimate the dispersal distances of pyroclasts in the submarine environment. Next, in chapter 4, we consider the effect of a uniform lateral crossflow on the dynamics of particle-laden fountains. We perform a series of analogue …
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3D and 4D Modeling of Ignimbrite Eruptions
… surrounding the volcanoes. Early detection of eruptions is the most important aspect when trying to reduce casualties from an eruption. The magma chamber at Yellowstone has been mapped previously using Seismic data and other methods, but more information is needed to predict the next eruptive …
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GEOCHEMISTRY OF LARGE EXPLOSIVE ERUPTIONS FROM THE MAIN ETHIOPIAN RIFT
… Quaternary, numerous high-magnitude explosive eruptions fed by SiO2-rich magmas, blanketed extensive areas both within and beyond the Rift Valley, making their deposits important stratigraphic markers at a regional scale. These eruptions represent the culmination of various processes leading to …
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Embayments in explosive, silicic eruptions : a textural, numerical, and experimental assessment.
… researchers going forward. My work on rhyolitic eruptions shows that embayments are common across eruptions. The range in embayment shapes and textures preserves a record of three separate timescales: diffusion speedometry, emptying, and faceting.
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Geochemical and volcanological aspects of rhyolite eruptions from Taupo Volcanic Zone, New Zealand
… zone on Earth, with more than 50 rhyolitic eruptions from its active volcanic centres, Okataina (OVC) and Taupo (TVC), in the last 50 kyr. The millennial-scale frequency of eruptions in the TVZ implies that the magmatic systems may not be analogous to those documented at other rhyolitic …
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Perchlorate Variations Over 300 Years: Influence of Human Activities, Volcanic Eruptions and Bolide Events
… a link between large, stratospheric volcanic eruptions and brief periods of increased perchlorate concentrations has been discovered. These volcanic eruptions increase stratospheric H2SO4 aerosols, which provides a surface for heterogeneous chlorine activation, resulting in increased …
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Study of magnetic helicity in solar active regions and its relationship with solar eruptions
… energy buildup and instability leading to solar eruptions. However, in spite of many years of study, detailed aspects of initiation mechanisms of eruptive events are still not well understood. The objective of this dissertation is to understand a long-term (a few days) variation of magnetic …
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A comprehensive study of evolution of photospheric magnetic field and flows associated with solar eruptions
The rapid, irreversible change of the photospheric magnetic field has been recognized as an important element of the solar flare process. Recent theoretical work has shown that such a change would imply Lorentz force perturbations acting on both the outer solar atmosphere and the solar surface. …
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CO2 Adsorption On Volcanic Ash: Net Contribution Of Volcanic Eruptions To The Global Carbon Cycle
… to be only a source of co2, but pyroclastic eruptions can also potentially serve as a sink. Adsorption was investigated for 6 volcanic ash samples of andesitic composition from four volcanoes: Okmok, Redoubt, Spurr, and Tungurahua. The eruption of volcano redoubt released 0.75 x 109 metric …
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UNDERSTANDING ERUPTIVE DYNAMICS, PLUME DISPERSAL AND PARTICLE TRANSPORT FOR RISK ASSESSMENT IN PAROXYSMAL MAFIC ERUPTIONS
… to reducing the risk associated with these eruptions. This thesis presents a study of several lava-fountain episodes at Etna that occurred between 2021 and 2024. Its aim is to improve our understanding of eruptive dynamics and better characterize key eruptive parameters used in monitoring …
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Utilizing Changes in Repeating Earthquakes to Monitor Evolving Processes and Structure Before and During Volcanic Eruptions
… have been observed prior to several volcanic eruptions, are thought to occur in response to volumetric strain and the opening or closing of cracks in the subsurface. We compared continuous records of velocity change against other geophysical data, and found that velocities at Mount St. Helens …
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The eruptions of Örӕfajökull 1362 (Iceland) and Lanzarote 1730-36 (Canary Islands) : sulphur emissions and volcanology
This thesis presents new data on the volcanology, erupted volumes, and sulphur emissions of the AD 1362 Örӕfajökull eruption and the AD 1730-36 Lanzarote eruption, and relates these findings to their atmospheric and environmental impacts. The Örӕfajökull eruption was an explosive Plinian event with …
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