With PQDT Open, you can read the full text of open access dissertations and theses free of charge.
About PQDT Open
Search
COMING SOON! PQDT Open is getting a new home!
ProQuest Open Access Dissertations & Theses will remain freely available as part of a new and enhanced search experience at www.proquest.com.
Questions? Please refer to this FAQ.
Seismic data from the intermediate-spreading Endeavour segment of the Juan de Fuca Ridge reveal several crustal-level, low-velocity, high-attenuation regions on the eastern and western ridge flanks 7 to 16 km from the neovolcanic zone. I examine Pg amplitude anomalies for a wide variety of source-receiver azimuths in the Endeavour active source seismic tomography data. I use finite difference waveform forward modeling to estimate the dimensions, depth, and seismic properties of the best-observed inferred anomalous regions. The attenuating regions extend 10–15 km beneath axis-parallel bathymetric highs and from 2 to 4 km below the seafloor. The velocity reduction is small (∼8%) and the attenuation large ( QP ≈ 8–40) suggesting the presence of partial melt. I infer that melt focusing toward the neovolcanic zone is incomplete and that tectonic interactions with the Heckle seamount chain and/or the large segment-bounding overlapping spreading centers may promote off-axis melt delivery at the Endeavour segment.
Advisor: | Hooft, Emilie |
Commitee: | Humphreys, Eugene, Toomey, Douglas, Wilcock, William |
School: | University of Oregon |
Department: | Department of Geological Sciences |
School Location: | United States -- Oregon |
Source: | MAI 50/05M, Masters Abstracts International |
Source Type: | DISSERTATION |
Subjects: | Geology, Geophysics |
Keywords: | Geology, Geophysics, Magma, Marine, Seismology |
Publication Number: | 1508954 |
ISBN: | 978-1-267-29032-8 |