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Access Type

WSU Access

Date of Award

January 2025

Degree Type

Thesis

Degree Name

M.S.

Department

Geology

First Advisor

Scott Burdick

Abstract

We introduce a probabilistic three-dimensional tomography approach to image Alaska’s lithosphere using ambient-noise Rayleigh wave dispersion and Poisson Voronoi (PV) inversion. Empirical Green’s functions from ∼1,000 broadband stations are processed via an automated Frequency–Time Analysis workflow to extract phase velocities between 8 and 50 s periods, employing uniform spectral whitening and a strict signal-to-noise ratio threshold. These measurements are converted into depth-dependent sensitivity kernels using direct inversion theory and mapped onto a 3D grid. A probabilistic PV method with nonlinear radial flattening (γ = 1.2) performs 500 low-dimensional inversions of 3,000 randomly distributed Voronoi cells, yielding an ensemble mean shear-wave velocity model to 240 km depth and corresponding uncertainty estimates. The resulting velocity distribution delineates major tectonic terranes and highlights areas of elevated uncertainty associated with sparse data coverage. This framework provides a robust foundation for joint inversion with body wave data and enhanced crustal corrections in seismic studies.

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