Humphreys, EugeneNiday, William2020-02-272020-02-272020-02-27https://hdl.handle.net/1794/25265We use a dense network of observations and an automated method of analysis to investigate complex patterns of seismic anisotropy in eastern Oregon. We present SKS splitting results for approximately 220 broadband seismic stations in the Pacific Northwest, including 33 stations from the new Wallowa2 array deployed between 2016 and 2018 in northeast Oregon. Our data set contains approximately 3300 splitting measurements. Over most of the Pacific Northwest, SKS splitting is consistent with a conceptual model of broadly east-west mantle flow redirected in places by lithospheric strength variations. However, splitting analysis performs poorly in northeast Oregon, and results are not consistent with uniform or layered anisotropy. We argue that anisotropy in NE Oregon is laterally heterogeneous on small scale, and propose a model that attributes complex splitting behavior to the seismically imaged Wallowa high-velocity anomaly.en-USAll Rights Reserved.Electronic Thesis or Dissertation