Publication Date

12-2017

Date of Final Oral Examination (Defense)

10-25-2017

Type of Culminating Activity

Thesis

Degree Title

Master of Science in Geophysics

Department

Geosciences

Supervisory Committee Chair

Dylan Mikesell, Ph.D.

Supervisory Committee Member

Jeffrey B. Johnson, Ph.D.

Supervisory Committee Member

Lee M. Liberty, M.S.

Abstract

Coseismic ionospheric disturbances (CID) are commonly identified using global navigation space system (GNSS) satellites. Little research, however, has focused on using total electron content (TEC) observations to characterize acoustic sources on Earth's surface. For this thesis, I investigate the applicability of an analytical method to invert the TEC for the acoustic wave. The inversion is based on the modeling of a transfer function. Deconvolving the TEC by the transfer function gives the acoustic wave. Inverting for the acoustic wave in this way would remove phase differences in the TEC created by atmospheric-ionospheric coupling. I test the assumption in the model of a 1D, vertically varying ionosphere by comparing numerical models of the TEC using 1D and 3D electron density divergences. I find the results are complex and recommend obtaining a transfer function that includes a 3D ionosphere. Regardless, even with the phase shift introduced by ionospheric coupling, we are able to apply seismic methods to the TEC.

I show an example of applying seismic methods to the TEC of the 2016 Kaikoura earthquake. In this chapter, I highlight the ionospheric response to the rupture. I use numerical modeling and find the TEC response to be more consistent with an acoustic source located northeast of the initial rupture. I also apply backprojection to the TEC for the first time and obtain a source just northwest of the rupture area. The errors in the backprojection are consistent with expected errors from local winds, which were not included in the model. Besides accounting for local winds in future work, inversion of the acoustic wave should also improve backprojection results by removing phase differences in the TEC.

DOI

https://doi.org/10.18122/B2WD97

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