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    Earthquake behavior and structure of oceanic transform faults

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    Roland_thesis.pdf (183.0Mb)
    Date
    2012-02
    Author
    Roland, Emily C.  Concept link
    Metadata
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    Citable URI
    https://hdl.handle.net/1912/5011
    Location
    East Pacific Rise
    DOI
    10.1575/1912/5011
    Keyword
     Faults; Thermal analysis 
    Abstract
    Oceanic transform faults that accommodate strain at mid-ocean ridge offsets represent a unique environment for studying fault mechanics. Here, I use seismic observations and models to explore how fault structure affects mechanisms of slip at oceanic transforms. Using teleseismic data, I find that seismic swarms on East Pacific Rise (EPR) transforms exhibit characteristics consistent with the rupture propagation velocity of shallow aseismic creep transients. I also develop new thermal models for the ridge-transform fault environment to estimate the spatial distribution of earthquakes at transforms. Assuming a temperature-dependent rheology, thermal models indicated that a significant amount of slip within the predicted temperature-dependent seismogenic area occurs without producing large-magnitude earthquakes. Using a set of local seismic observations, I consider how along-fault variation in the mechanical behavior may be linked to material properties and fault structure. I use wide-angle refraction data from the Gofar and Quebrada faults on the equatorial EPR to determine the seismic velocity structure, and image wide low-velocity zones at both faults. Evidence for fractured fault zone rocks throughout the crust suggests that unique friction characteristics may influence earthquake behavior. Together, earthquake observations and fault structure provide new information about the controls on fault slip at oceanic transform faults.
    Description
    Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution February 2012
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    • Geology and Geophysics (G&G)
    • WHOI Theses
    Suggested Citation
    Thesis: Roland, Emily C., "Earthquake behavior and structure of oceanic transform faults", 2012-02, DOI:10.1575/1912/5011, https://hdl.handle.net/1912/5011
     

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