Earth and Planetary Sciences ETDs

Publication Date

Summer 6-22-2022

Abstract

Seismology provides valuable observational constraints to thermal and compositional states at inaccessible depths via understanding how elastic wave propagating through them. While many of fundament questions regarding solid Earth structures have been addressed during its more than 100 years history, some details remain unfilled and carefully designed approaches are needed to complete the pictures. This dissertation contributes observational constraints on three topics with newly developed methods. 1) We detected a controversial mantle discontinuity at about 520 km and concluded a mean mantle composition close to the Pyrolite model based on its seismic properties. 2) We isolated anisotropic effects in mantle transition zone from above and below the layer and hypothesized that concentrated mantle flow near slab gaps enhances local stress and aligns minerals at the depths. 3) We revisited hypocenter estimates of catalog earthquakes near Mount St. Helens and revealed similar depth distributions of the seismicity before and after its 2004-2008 eruption, suggesting a quick re-equilibrium of the magmatic system. These observations highlights seismology’s role in advancing our understanding to various aspects of the Plate Tectonics.

Degree Name

Earth and Planetary Sciences

Level of Degree

Doctoral

Department Name

Department of Earth and Planetary Sciences

First Committee Member (Chair)

Brandon Schmandt

Second Committee Member

Jin Zhang

Third Committee Member

Peter Olson

Fourth Committee Member

Mousumi Roy

Language

English

Keywords

seismology, mantle, anisotropy, volcano

Document Type

Dissertation

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