Investigating Tectonic Structures in East Antarctica Using Full Waveform Ambient Noise Tomography
Electronic Thesis or Dissertation Previous investigations have proposed multiple origin models to explain the formation of major tectonic structures, such as the Gamburtsev Subglacial Mountains (GSMs), the Wilkes Subglacial Basin (WSB), the Aurora Subglacial Basin (ASB), and the Transantarctic Mount...
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ftunivalabama:oai:ir.ua.edu:123456789/8183 2023-05-15T13:56:41+02:00 Investigating Tectonic Structures in East Antarctica Using Full Waveform Ambient Noise Tomography Kumar, Ashish Hansen, Samantha 2021 http://ir.ua.edu/handle/123456789/8183 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/123456789/8183 All rights reserved by the author unless otherwise indicated. Ambient Noise Tomography Antarctica Crust and Upper Mantle Structure thesis text 2021 ftunivalabama 2023-01-07T16:38:57Z Electronic Thesis or Dissertation Previous investigations have proposed multiple origin models to explain the formation of major tectonic structures, such as the Gamburtsev Subglacial Mountains (GSMs), the Wilkes Subglacial Basin (WSB), the Aurora Subglacial Basin (ASB), and the Transantarctic Mountains (TAMs) in East Antarctica. However, existing tomographic images lack resolution and consistency given the sparse seismic coverage across the continent, particularly in East Antarctica. In this thesis, I use full-waveform ambient noise tomography to model the shear-wave velocity structure beneath East Antarctica to further investigate these tectonic features and to provide new insights into existing origin models. This technique has been shown to provide improved resolution of the seismic structure in geographic regions with limited station coverage compared to more traditional tomographic approaches. Rayleigh-wave Empirical Green’s Functions are extracted from ambient noise using a frequency-time normalization technique. Synthetic waveforms are simulated with a lateral grid spacing of 0.025º (~2.25 km) and are cross-correlated with the EGFs to measure phase delays. The shear-wave velocity model is computed by inverting the phase delays using a sparse, damped least-squares inversion method. The new tomographic model shows fast velocities beneath the GSMs that extend to ~250 km depth, suggesting Archean or Proterozoic lithosphere beneath the mountain range. The perseverance of thick ancient crust beneath the GSMs support the high topography of the mountain range. Slow upper mantle velocities are observed beneath the TAMs, likely associated with hot upper mantle material that provides a thermal load beneath the mountain range, consistent with a flexural uplift model. Beneath the WSB, fast seismic velocities are attributed to thick, stable lithosphere, also consistent with a flexural origin model. Slow velocities beneath the ASB, which is an area of particular interest since it has not been studied extensively, may ... Thesis Antarc* Antarctica East Antarctica University of Alabama Institutional Repository East Antarctica Gamburtsev Subglacial Mountains ENVELOPE(76.000,76.000,-80.500,-80.500) Perseverance ENVELOPE(162.200,162.200,-76.800,-76.800) Transantarctic Mountains Wilkes Subglacial Basin ENVELOPE(145.000,145.000,-75.000,-75.000) |
institution |
Open Polar |
collection |
University of Alabama Institutional Repository |
op_collection_id |
ftunivalabama |
language |
English |
topic |
Ambient Noise Tomography Antarctica Crust and Upper Mantle Structure |
spellingShingle |
Ambient Noise Tomography Antarctica Crust and Upper Mantle Structure Kumar, Ashish Investigating Tectonic Structures in East Antarctica Using Full Waveform Ambient Noise Tomography |
topic_facet |
Ambient Noise Tomography Antarctica Crust and Upper Mantle Structure |
description |
Electronic Thesis or Dissertation Previous investigations have proposed multiple origin models to explain the formation of major tectonic structures, such as the Gamburtsev Subglacial Mountains (GSMs), the Wilkes Subglacial Basin (WSB), the Aurora Subglacial Basin (ASB), and the Transantarctic Mountains (TAMs) in East Antarctica. However, existing tomographic images lack resolution and consistency given the sparse seismic coverage across the continent, particularly in East Antarctica. In this thesis, I use full-waveform ambient noise tomography to model the shear-wave velocity structure beneath East Antarctica to further investigate these tectonic features and to provide new insights into existing origin models. This technique has been shown to provide improved resolution of the seismic structure in geographic regions with limited station coverage compared to more traditional tomographic approaches. Rayleigh-wave Empirical Green’s Functions are extracted from ambient noise using a frequency-time normalization technique. Synthetic waveforms are simulated with a lateral grid spacing of 0.025º (~2.25 km) and are cross-correlated with the EGFs to measure phase delays. The shear-wave velocity model is computed by inverting the phase delays using a sparse, damped least-squares inversion method. The new tomographic model shows fast velocities beneath the GSMs that extend to ~250 km depth, suggesting Archean or Proterozoic lithosphere beneath the mountain range. The perseverance of thick ancient crust beneath the GSMs support the high topography of the mountain range. Slow upper mantle velocities are observed beneath the TAMs, likely associated with hot upper mantle material that provides a thermal load beneath the mountain range, consistent with a flexural uplift model. Beneath the WSB, fast seismic velocities are attributed to thick, stable lithosphere, also consistent with a flexural origin model. Slow velocities beneath the ASB, which is an area of particular interest since it has not been studied extensively, may ... |
author2 |
Hansen, Samantha |
format |
Thesis |
author |
Kumar, Ashish |
author_facet |
Kumar, Ashish |
author_sort |
Kumar, Ashish |
title |
Investigating Tectonic Structures in East Antarctica Using Full Waveform Ambient Noise Tomography |
title_short |
Investigating Tectonic Structures in East Antarctica Using Full Waveform Ambient Noise Tomography |
title_full |
Investigating Tectonic Structures in East Antarctica Using Full Waveform Ambient Noise Tomography |
title_fullStr |
Investigating Tectonic Structures in East Antarctica Using Full Waveform Ambient Noise Tomography |
title_full_unstemmed |
Investigating Tectonic Structures in East Antarctica Using Full Waveform Ambient Noise Tomography |
title_sort |
investigating tectonic structures in east antarctica using full waveform ambient noise tomography |
publisher |
University of Alabama Libraries |
publishDate |
2021 |
url |
http://ir.ua.edu/handle/123456789/8183 |
long_lat |
ENVELOPE(76.000,76.000,-80.500,-80.500) ENVELOPE(162.200,162.200,-76.800,-76.800) ENVELOPE(145.000,145.000,-75.000,-75.000) |
geographic |
East Antarctica Gamburtsev Subglacial Mountains Perseverance Transantarctic Mountains Wilkes Subglacial Basin |
geographic_facet |
East Antarctica Gamburtsev Subglacial Mountains Perseverance Transantarctic Mountains Wilkes Subglacial Basin |
genre |
Antarc* Antarctica East Antarctica |
genre_facet |
Antarc* Antarctica East Antarctica |
op_relation |
The University of Alabama Electronic Theses and Dissertations The University of Alabama Libraries Digital Collections http://ir.ua.edu/handle/123456789/8183 |
op_rights |
All rights reserved by the author unless otherwise indicated. |
_version_ |
1766264259823534080 |