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Earth Rotation and Deformation Signals Caused by Deep Earth Processes

Watkins, Andrew
http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1510767104519046

Abstract Details

2017, Master of Science (MS), Bowling Green State University, Geology.
The length of a day on Earth (abbreviated LOD) is not exactly 24 hours. There is a small excess LOD that varies on timescales ranging from a few days to thousands of years, generally on the order of milliseconds. One characteristic of LOD variations is a sinusoidal component with a period of ~6 years. The cause of the ~6-year signal is unknown, but is generally suspected to be exchanges of angular momentum between the mantle and the core. This study aimed to test the hypothesis that the ~6-year LOD signal is due to coupling between the mantle and fluid outer core. The flow of the core's fluid deforms the base of the mantle, leading to redistribution of Earth's mass (causing changes in the gravitational field) and deformation of the overlying crust. Surface deformation data from a global network of high-precision Global Positioning System (GPS) stations was analyzed, and the component that acts on the ~6-year timescale was isolated and inverted for the core's flow. Resulting angular momentum changes were computed for the outer core and compared to the LOD signal to search for evidence of core-mantle coupling. Outer core angular momentum changes obtained from GPS deformation data exhibit evidence of the suspected core-mantle coupling, but this result is sensitive to inversion parameters. Changes in the gravitational field were also modeled and found to be smaller than the errors in the currently available data.
Yuning Fu, PhD (Advisor)
Richard Gross, PhD (Committee Member)
Marco Nardone, PhD (Committee Member)
Margaret Yacobucci, PhD (Committee Member)
58 p.
Geology; Geophysics
Geology; Geophysics; Earth Interior; Outer Core; Surface Deformation; Crustal Deformation; Global Positioning System; GPS; Gravitational Potential; Geopotential; Earth Orientation; Earth Rotation; Length of Day; LOD; Angular Momentum;

Recommended Citations

Citations

  • Watkins, A. (2017). Earth Rotation and Deformation Signals Caused by Deep Earth Processes [Master's thesis, Bowling Green State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1510767104519046

    APA Style (7th edition)

  • Watkins, Andrew. Earth Rotation and Deformation Signals Caused by Deep Earth Processes. 2017. Bowling Green State University, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1510767104519046.

    MLA Style (8th edition)

  • Watkins, Andrew. "Earth Rotation and Deformation Signals Caused by Deep Earth Processes." Master's thesis, Bowling Green State University, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1510767104519046

    Chicago Manual of Style (17th edition)

bgsu1510767104519046
536
© 2017, some rights reserved.Creative Commons License Earth Rotation and Deformation Signals Caused by Deep Earth Processes by Andrew Watkins is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported License. Based on a work at etd.ohiolink.edu.
This open access ETD is published by Bowling Green State University and OhioLINK.