Doctoral Dissertations

Keywords and Phrases

Attenuation Tomography; Continental Lithosphere; Seismic Wave Attenuation; Upper Mantle; Young Rift

Abstract

"Seismic attenuation is an important physical parameter for characterizing subsurface morphology and the thermal structure of the Earth’s crust and mantle. In this study, teleseismic P-wave amplitude spectra are used to examine the seismic attenuation beneath the southeastern United States and the Malawi and Luangwa rift zones in east African. The resulting seismic attenuation parameters (Δt*) reveal a systematic contrast between the Appalachian Mountains and the Gulf of Mexico Coastal Plain exhibiting high and low attenuation, respectively. Spatial coherency analysis of the Δt* observations suggests that the center of the low-attenuation layer is located within the uppermost mantle at about 70 km depth. The origin of this low-attenuation anomaly can be attributed to low-attenuation bodies in the form of remnant fossil lithospheric fragments in the deep crust or the uppermost mantle. The contribution of scattering to the observed Δt* is relatively weaker in the Gulf of Mexico Coastal Plain, which is suggestive of a more homogenous crustal and uppermost mantle structure. The first regional-scale 3-D P- wave attenuation model demonstrates high-attenuation anomalies at the northern and southern tips of the Malawi Rift Zone (MRZ) and an elongated NE-SW strip of low- attenuation anomaly traversing central MRZ. The high attenuation zone beneath the Rungwe Volcanic Province is confined to the upper mantle, which can be associated with decompression melting in response to continental extension. The prominent low- attenuation anomaly beneath the Luangwa Rift Zone that traverses the central part of the MRZ suggests the presence of a relatively thick cratonic lithosphere and possibly advocates the southward subsurface extension of the Bangweulu block"--Abstract, page iv.

Advisor(s)

Liu, Kelly H.
Gao, Stephen S.

Committee Member(s)

Rogers, J. David
Anderson, Neil L. (Neil Lennart), 1954-
Wei, Mingzhen

Department(s)

Geosciences and Geological and Petroleum Engineering

Degree Name

Ph. D. in Geology and Geophysics

Comments

The study was partially supported by the U.S. National Science Foundation under Grant No. 1919789.

Publisher

Missouri University of Science and Technology

Publication Date

Summer 2021

Journal article titles appearing in thesis/dissertation

  • Teleseismic P-wave attenuation beneath the southeastern United States
  • Upper mantle attenuation structure beneath the Malawi and Luangwa rift zones in East Africa

Pagination

x, 120 pages

Note about bibliography

Includes bibliographic references.

Rights

© 2021 Ashutosh Shrivastava, All rights reserved.

Document Type

Dissertation - Open Access

File Type

text

Language

English

Thesis Number

T 11922

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