A 2-D Magnetotelluric Investigation of the Cascadia Subduction Zone
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Date
2016-06
Authors
Wogan, Nicholas
Journal Title
Journal ISSN
Volume Title
Publisher
University of Oregon
Abstract
I have produced four 2-D magnetotelluric conductivity inversions of MOCHA
data roughly between the latitudes of 43N and 46N that indicate fluid variation along
strike in the Cascadia subduction zone. I directly compare these results to Wannamaker
et al. 2014 EMSLAB inversion and find the models to be very similar despite the use of
different data sets and inversion methods. Conductivity structure along the plate
interface supports the hypothesis that there is "partial creeping" occurring in the locked
zone in central Cascadia, as well as the possible presence of a secondary, inboard
locked zone at 44.5N in the ETS region. The variability of conductivity along strike also
suggests a more permeable crust in the northern region of Cascadia directly overhead
the ETS zone, and more fluid accumulation in this same region. This study indicates
that a more permeable overlying crust, combined with larger amounts of fluid present
may be critical components of rapid ETS occurrence.
Description
39 pages. A thesis presented to the Department of Physics and the Clark Honors College of the University of Oregon in partial fulfillment of the requirements for degree of Bachelor of Science, Spring 2016.
Keywords
Geophysics, Geology, Magnetotellurics, Cascadia, Subduction Zone, Megathrust, Earthquake