Earth Inner Core Anisotropy as Observed by PKiKP and PKIIKP Reflected Waves

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dc.contributor.advisorZheng, Yingcai
dc.contributor.committeeMemberLapen, Thomas J.
dc.contributor.committeeMemberThomsen, Leon
dc.contributor.committeeMemberSuppe, John
dc.contributor.committeeMemberNiu, Fenglin
dc.creatorChew, Jessica M. 1994-
dc.date.accessioned2018-11-30T16:40:31Z
dc.date.available2018-11-30T16:40:31Z
dc.date.createdMay 2018
dc.date.issued2018-05
dc.date.submittedMay 2018
dc.date.updated2018-11-30T16:40:31Z
dc.description.abstractThe idea of Earth inner core anisotropy is well-established, and it is a very important topic in understanding the planet’s core growth, magnetic dynamo, and evolution. Most data analysis techniques used to measure the anisotropy use the differential traveltimes between transmitted wave pairs, which mostly sample only shallow parts of the inner core or may be affected by mantle heterogeneities. We introduce a new method to study the effects of solely the whole inner core using a pair of reflected PKiKP and PKIIKP waves at small epicentral distances (up to 40 degrees). We take the differential traveltime between the PKiKP and PKIIKP arrivals. This differential time measures the two-way traveltime of the P-wave, which samples both the shallow and deep parts of the inner core. This observation geometry yields a clean time window in which these phases can be identified. The small epicentral distance is key to minimizing effects of small mantle heterogeneities. Data for this project include seismograms obtained from the Incorporated Research Institutions for Seismology (IRIS) database for global earthquakes from 1990 to 2016 of moment magnitudes 6.1-6.5. Seismic data were loaded into a MATLAB® GUI program to identify PKiKP-PKIIKP phase pairs at the same station. I have identified an initial set of 99 traveltime pairs from the single-trace seismograms and plotted them against latitude and longitude. No systematic change of differential time with respect to latitude was seen, which implies an anisotropy structure that is in sharp contrast to the commonly observed polar dependence anisotropy. In order to increase the signal-to-noise ratio (SNR), I stacked signals from an array of seismometers for each earthquake. From these cleaner stacked seismograms, I found 59 traveltime pairs that suggest a different view on Earth’s inner core anisotropy, which was similar to the single-trace seismogram observations.
dc.description.departmentEarth and Atmospheric Sciences, Department of
dc.format.digitalOriginborn digital
dc.format.mimetypeapplication/pdf
dc.identifier.urihttp://hdl.handle.net/10657/3468
dc.language.isoeng
dc.rightsThe author of this work is the copyright owner. UH Libraries and the Texas Digital Library have their permission to store and provide access to this work. Further transmission, reproduction, or presentation of this work is prohibited except with permission of the author(s).
dc.subjectInner core
dc.subjectAnisotropy
dc.subjectPKiKP
dc.subjectPKIIKP
dc.titleEarth Inner Core Anisotropy as Observed by PKiKP and PKIIKP Reflected Waves
dc.type.dcmiText
dc.type.genreThesis
local.embargo.lift2020-05-01
local.embargo.terms2020-05-01
thesis.degree.collegeCollege of Natural Sciences and Mathematics
thesis.degree.departmentEarth and Atmospheric Sciences, Department of
thesis.degree.disciplineGeophysics
thesis.degree.grantorUniversity of Houston
thesis.degree.levelMasters
thesis.degree.nameMaster of Science

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