An 80 km seismic refraction line was recorded on an array
of three ocean bottom seismometers located 5 km west of the
northern tip of Explorer ridge and parallel to Revere-Dellwood
fracture zone on the Pacific plate. One reversed and two
split-spread profiles have been obtained. The combined use of
rotated SV component and polarization filtered record sections
enabled identification and timing of the refracted S-wave on
most sections. The travel time - distance relation for both P
and S waves is interpreted in the intercept time (tau) and ray
parameter domain using the technique introduced by Bessonova
et al. (1974). This enables application of tau inversion to
give extremal bounds for velocity-depth curves. A linearized
inversion technique is applied to give the smoothest velocity-depth
profiles consistent with the travel time data.
Amplitude analysis using disk ray theory synthetic seismograms
further refine the P-wave velocity-depth models.
The final P- and S-wave velocity-depth profiles show a
general increase of velocity with depth and no distinct
structural discontinuities. A normal oceanic crustal
thickness of approximately 6.5 km and an anomalously low Pn
velocity of 7.3 km sec⁻¹ are interpreted. The existence of an
abnormally thick crust (8-10 km}., on the opposite side of the
ridge in Explorer plate, determined in other studies,
contrasts markedly with the results of this research. Such a
contrast lends support to the proposal that the complex
structure and thick crust are the result of compressive
interaction between the young, small Explorer plate and the
older, larger North America plate. Values of Poisson's ratio
in the range of 0.25 to 0.32 are determined for the crustal
material but better resolution of the velocity-depth profiles
is required before a meaningful geological interpretation can
be made. / Science, Faculty of / Earth, Ocean and Atmospheric Sciences, Department of / Graduate
| Identifer | oai:union.ndltd.org:UBC/oai:circle.library.ubc.ca:2429/30299 |
| Date | January 1978 |
| Creators | Cheung, Henry P. Y. |
| Publisher | University of British Columbia |
| Source Sets | University of British Columbia |
| Language | English |
| Detected Language | English |
| Type | Text, Thesis/Dissertation |
| Rights | For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use. |
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