Investigating ultra-low velocity zones at the core-mantle boundary beneath the Southern Hemisphere using an Antarctic dataset
Electronic Thesis or Dissertation The core-mantle boundary (CMB) represents the largest absolute density contrast on our planet, and it is associated with significant heterogeneities. The CMB structure focused on in this study are ultra-low velocity zones (ULVZs), laterally-varying, 5-50 km thick is...
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ftunivalabama:oai:ir.ua.edu:123456789/5419 2023-05-15T13:56:41+02:00 Investigating ultra-low velocity zones at the core-mantle boundary beneath the Southern Hemisphere using an Antarctic dataset Carson, Sarah Hansen, Samantha E. Mahatsente, Rezene Stowell, Harold Hilton Garnero, Edward J. 2018 89 p. http://ir.ua.edu/handle/123456789/5419 English eng University of Alabama Libraries The University of Alabama Electronic Theses and Dissertations The University of Alabama Libraries Digital Collections http://ir.ua.edu/handle/123456789/5419 All rights reserved by the author unless otherwise indicated. Geophysics Geology thesis text 2018 ftunivalabama 2023-01-07T16:41:04Z Electronic Thesis or Dissertation The core-mantle boundary (CMB) represents the largest absolute density contrast on our planet, and it is associated with significant heterogeneities. The CMB structure focused on in this study are ultra-low velocity zones (ULVZs), laterally-varying, 5-50 km thick isolated patches seen in some locations just above the CMB that are associated with increased density and reduced seismic wave velocities. The variable characteristics associated with ULVZs have led to many questions regarding their origins, but only about 17% of the CMB has been surveyed for the presence of ULVZs given limited seismic coverage of the lowermost mantle. Therefore, investigations that sample the CMB with new geometries are critical to further our understanding of ULVZs and their potential connection to other deep Earth processes. The Transantarctic Mountains Northern Network (TAMNNET), a 15-station seismic array that was deployed in Antarctica from 2012-2015, provides a unique dataset to further study ULVZ structure with new and unique path geometry. Core-reflected ScP phases recorded by TAMNNET well sample the CMB in the vicinity of New Zealand in the southwestern Pacific, providing coverage between an area to the northeast where ULVZ structure has been previously identified and another region to the south, where ULVZ evidence is inconclusive. This area is of particular interest because the data sample across the boundary of the Pacific Large Low Shear Velocity Province (LLSVP). The Weddell Sea region near Antarctica is also well sampled in this study, providing new information on this area that has not been previously studied. By identifying and modeling energy associated with the ScP waveform, new portions of the CMB have been explored and evidence for ULVZs in both regions has been found. A correlative scheme between 1-D synthetic seismograms and observed data demonstrate that ULVZs are required in the study regions, but modeling uncertainties limit the ability to definitively define ULVZ ... Thesis Antarc* Antarctic Antarctica Weddell Sea University of Alabama Institutional Repository Antarctic New Zealand Pacific Transantarctic Mountains Weddell Weddell Sea |
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University of Alabama Institutional Repository |
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English |
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Geophysics Geology |
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Geophysics Geology Carson, Sarah Investigating ultra-low velocity zones at the core-mantle boundary beneath the Southern Hemisphere using an Antarctic dataset |
topic_facet |
Geophysics Geology |
description |
Electronic Thesis or Dissertation The core-mantle boundary (CMB) represents the largest absolute density contrast on our planet, and it is associated with significant heterogeneities. The CMB structure focused on in this study are ultra-low velocity zones (ULVZs), laterally-varying, 5-50 km thick isolated patches seen in some locations just above the CMB that are associated with increased density and reduced seismic wave velocities. The variable characteristics associated with ULVZs have led to many questions regarding their origins, but only about 17% of the CMB has been surveyed for the presence of ULVZs given limited seismic coverage of the lowermost mantle. Therefore, investigations that sample the CMB with new geometries are critical to further our understanding of ULVZs and their potential connection to other deep Earth processes. The Transantarctic Mountains Northern Network (TAMNNET), a 15-station seismic array that was deployed in Antarctica from 2012-2015, provides a unique dataset to further study ULVZ structure with new and unique path geometry. Core-reflected ScP phases recorded by TAMNNET well sample the CMB in the vicinity of New Zealand in the southwestern Pacific, providing coverage between an area to the northeast where ULVZ structure has been previously identified and another region to the south, where ULVZ evidence is inconclusive. This area is of particular interest because the data sample across the boundary of the Pacific Large Low Shear Velocity Province (LLSVP). The Weddell Sea region near Antarctica is also well sampled in this study, providing new information on this area that has not been previously studied. By identifying and modeling energy associated with the ScP waveform, new portions of the CMB have been explored and evidence for ULVZs in both regions has been found. A correlative scheme between 1-D synthetic seismograms and observed data demonstrate that ULVZs are required in the study regions, but modeling uncertainties limit the ability to definitively define ULVZ ... |
author2 |
Hansen, Samantha E. Mahatsente, Rezene Stowell, Harold Hilton Garnero, Edward J. |
format |
Thesis |
author |
Carson, Sarah |
author_facet |
Carson, Sarah |
author_sort |
Carson, Sarah |
title |
Investigating ultra-low velocity zones at the core-mantle boundary beneath the Southern Hemisphere using an Antarctic dataset |
title_short |
Investigating ultra-low velocity zones at the core-mantle boundary beneath the Southern Hemisphere using an Antarctic dataset |
title_full |
Investigating ultra-low velocity zones at the core-mantle boundary beneath the Southern Hemisphere using an Antarctic dataset |
title_fullStr |
Investigating ultra-low velocity zones at the core-mantle boundary beneath the Southern Hemisphere using an Antarctic dataset |
title_full_unstemmed |
Investigating ultra-low velocity zones at the core-mantle boundary beneath the Southern Hemisphere using an Antarctic dataset |
title_sort |
investigating ultra-low velocity zones at the core-mantle boundary beneath the southern hemisphere using an antarctic dataset |
publisher |
University of Alabama Libraries |
publishDate |
2018 |
url |
http://ir.ua.edu/handle/123456789/5419 |
geographic |
Antarctic New Zealand Pacific Transantarctic Mountains Weddell Weddell Sea |
geographic_facet |
Antarctic New Zealand Pacific Transantarctic Mountains Weddell Weddell Sea |
genre |
Antarc* Antarctic Antarctica Weddell Sea |
genre_facet |
Antarc* Antarctic Antarctica Weddell Sea |
op_relation |
The University of Alabama Electronic Theses and Dissertations The University of Alabama Libraries Digital Collections http://ir.ua.edu/handle/123456789/5419 |
op_rights |
All rights reserved by the author unless otherwise indicated. |
_version_ |
1766264262233161728 |