Understanding variations in deformation and seismic behavior at subduction zones

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dc.contributor.advisorMoore, Gregory F.
dc.contributor.authorTilley, Hannah
dc.contributor.departmentGeology and Geophysics
dc.date.accessioned2022-03-03T19:52:08Z
dc.date.issued2021
dc.description.degreePh.D.
dc.embargo.liftdate2023-03-02
dc.identifier.urihttp://hdl.handle.net/10125/81606
dc.subjectGeophysics
dc.subjectAccretionary
dc.subjectDeformation
dc.subjectHikurangi
dc.subjectNankai
dc.subjectSubdution
dc.titleUnderstanding variations in deformation and seismic behavior at subduction zones
dc.typeThesis
dcterms.abstractSubduction zone faults accommodate relative plate motions with spatially varying deformation and seismic behavior. Subducting topography and sediment properties play a key role in modulating the deformation and seismic behavior. We studied two subduction zones, the Nankai Trough and the Hikurangi margin, using new high resolution and 3D seismic data, as well as decades worth of legacy data, to constrain the subduction input and determine the relationship between the sediment and plate characteristics, and variations in deformation and seismic behavior at subduction zones. We found that subducting basement topography is the main driver of upper plate deformation above a site of slow earthquakes at the Hikurangi margin; the upper plate faults responsible for deformation in the mid-slope may be responsible for local microseismicity. We also found that the oceanic basement topography influences the location of contourites and turbidites, which results in highly localized heterogeneities in the porosity and permeability of sediment deposits. Upon subduction, these patchy deposits may result in localized compartments of excess pore pressure, which may pre-condition the plate interface for slow slip behavior. Subducting topography, as well as sediment thickness and lithology, also influences the width of protothrust zones, which form in localized areas seaward of the deformation front. The width of the protothrust zone is important because it influences the style of deformation along the frontal thrust. Our studies show that variations in the sediment characteristics of the incoming plate are highly localized, particularly in areas where there is significant basement topography. As a result, variations in deformation and seismic behavior at convergent margins are also highly localized. This variability needs to be considered at all subduction zones when assessing the seismic hazard potential of margins.
dcterms.extent171 pages
dcterms.languageen
dcterms.publisherUniversity of Hawai'i at Manoa
dcterms.rightsAll UHM dissertations and theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission from the copyright owner.
dcterms.typeText
local.identifier.alturihttp://dissertations.umi.com/hawii:11225

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Ph.D. - Geology and Geophysics