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- Antarctica (1)
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- Asteroid Vesta (1)
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Articles 1 - 7 of 7
Full-Text Articles in Physical Sciences and Mathematics
The Isotropic And Anisotropic Structure Of Antarctica From Seismic Inversion, Zhengyang Zhou
The Isotropic And Anisotropic Structure Of Antarctica From Seismic Inversion, Zhengyang Zhou
Arts & Sciences Electronic Theses and Dissertations
This dissertation utilizes multiple techniques of earthquake tomography to investigate the seismic structure of the crust and mantle beneath Antarctica. The isotropic structure of the Antarctic crust and upper mantle is now constrained by several seismic studies, but until now few studies have investigated the anisotropic structure. Therefore, in this study, I focus on the anisotropic structure, which is crucial information to understanding current or historic deformation and flow patterns, as well as the organic process of Antarctica. I use the data from the seismic stations deployed on the Antarctica continent during the past 20 years, as well as other …
Internal Structures And Spin Evolutions Of Small Bodies In The Solar System And Their Geophysical Implications: A Case Study On Ceres, Vesta, And Arrokoth, Xiaochen Mao
Arts & Sciences Electronic Theses and Dissertations
Asteroids and Kuiper belt objects are for the most part the remnant planetesimals that have not been able to form into planets. These small bodies’ evolutionary pathways encode information from the early days of the Solar System. Recent space missions such as Dawn and New Horizons have now made detailed geological investigations of small bodies (i. e. , Ceres, Vesta, and Arrokoth) possible. In this thesis, I use geophysical modeling to study small body internal structure and to investigate spin history under the influence of impacts. I analyze the gravity and shape data obtained by Dawn of Ceres and make …
Seismicity And Shallow Structure At The Mariana Subduction Zone, Melody Eimer
Seismicity And Shallow Structure At The Mariana Subduction Zone, Melody Eimer
Arts & Sciences Electronic Theses and Dissertations
This dissertation examines the incoming Pacific plate and the overriding forearc at the Mariana Subduction Zone using passive and active source seismology. The incoming plate, with water bound in the plate sediment, crust and mantle, is of interest to help constrain the global water cycle. The seismogenic zone at Mariana is noted for being an aseismic end-member, while extensional faults and active serpentine mud volcanoes characterize the forearc. I use an ocean bottom seismograph (OBS) deployment spanning both the incoming Pacific Plate and the forearc to study the seismicity and shallow structure. The passive source component of the deployment consists …
Evolution Of Olivine Crystallographic Preferred Orientation In The Upper Mantle -- Implications For The Interpretation Of Seismic Anisotropy, Yuval Boneh
Arts & Sciences Electronic Theses and Dissertations
Earth’s plate tectonics is the outermost manifestation of mantle convection. Understanding plate tectonics at the global scale requires understanding of regional processes near plate boundaries. Flow patterns in the upper mantle are generally inferred from observations of anisotropy of seismic wave speed. In plate interiors, where flow patterns are assumed to be simple, interpretation of seismic anisotropy is straightforward. However, near plate boundaries, where flow patterns are complex, different strategies for interpreting seismic anisotropy may be required. This dissertation examines, using experimental and numerical tools, the effects of complex flow patterns on the evolution of olivine crystallographic preferred orientation (CPO). …
Seismic Array Studies Of Antarctica And Madagascar, Martin James Pratt
Seismic Array Studies Of Antarctica And Madagascar, Martin James Pratt
Arts & Sciences Electronic Theses and Dissertations
The scope of this dissertation is broad, involving seismic array studies from Antarctica and Madagascar, and includes aspects of glaciology and oceanography as well as solid Earth geophysics. Chapter 2 focuses on the study of stickslip motion of the Whillans Ice Stream, West Antarctica. It includes methods combining seismic array and GPS time series, from ice stream based-sensors, to determine source dynamics in the framework of an earthquake source. The source characteristics are then analyzed to explain far-field seismic observations of ice stream- sourced surface waves detected throughout West Antarctica. Locations of asperities, or sticky- spots, that cause the Whillans …
Plate Tectonics Initiation On Earth-Like Planets: Insights From Numerical And Theoretical Analysis Of Convection-Induced Lithospheric Failure, Teresa Wong
Arts & Sciences Electronic Theses and Dissertations
Plate tectonics is central to many aspects of the geology and evolution of terrestrial planets, yet it is only observed on the Earth while all other known planets are covered with a stagnant lithosphere. Plate motions on the Earth are mostly driven by the pull of subducting slabs, therefore understanding the initiation of subduction is crucial to understanding plate tectonics initiation. On a one-plate planet which lacks the forces due to plate motions, some other mechanisms will have to cause the first episode of subduction to mobilize the surface. Sublithospheric convection has been proposed as a possible mechanism that induce …
Seismic Studies Of The Tonga Subduction Zone And The Lau Back-Arc Basin, Songqiao Wei
Seismic Studies Of The Tonga Subduction Zone And The Lau Back-Arc Basin, Songqiao Wei
Arts & Sciences Electronic Theses and Dissertations
This dissertation utilizes multiple techniques of seismic tomography and earthquake location to investigate the upper mantle structure and intermediate-depth seismicity of the Tonga subduction zone, the Lau back-arc basin, and adjacent regions. Data for these studies consist of broadband records from 49 ocean bottom seismographs and 17 island-based seismic stations deployed for one year in 2009-2010, as well as more limited earlier datasets. I conducted tomographic studies of Rayleigh wave velocity and body wave attenuation to examine the thermal variations and the distribution of partial melt in the mantle wedge. The shear-wave velocity structure is first determined using only teleseismic …