Earth and Planetary Sciences ETDs

Publication Date

Spring 5-1-2018

Abstract

Both the thermal structures and the hydrated level of the mantle transition zone are attractive to researchers in solid Earth science fields. Although some aspects of the questions have been answered based on current geophysical observations, a high resolution seismic map of such layer on a continental scale is still valuable for improving our understanding of the lateral variations inside the mantle transition zone. Here we extend a 3D pre-stacking migration method to make it more applicable for imaging the mantle transition zone depths. After the validation of the method with 1D synthetic data, two types of 2D structures are adapted for exhibiting the advantages and disadvantages of different practical imaging parameters. The results indicate that the method is capable of mapping dipping anomalies as well as discrete low velocity layers. Some practical parameters, such as the slowness window and the wavelet can heavily affect the migrated results. It is suggested to choose these imaging parameters based on the understanding of the primary targets as well as associated synthetic tests. Finally, the observed data from the USArray are migrated with the new method. The profiles show the major discontinuities, the 410 and the 660, inside the mantle transition zone clearly. Some topographic changes of the two interfaces are consistent with the prediction from mineral physics in sign while a few are not. The observation suggests factors other than temperature may also have influences on the topography of the two discontinuities in the region.

Degree Name

Earth and Planetary Sciences

Level of Degree

Masters

Department Name

Department of Earth and Planetary Sciences

First Committee Member (Chair)

Brandon Schmandt

Second Committee Member

Jin Zhang

Third Committee Member

Mousumi Roy

Language

English

Keywords

Seismology, Receiver Function, Mantle Transition Zone

Document Type

Thesis

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