Title

Experimental realization of seabed shear modulus profile inversion methods

Date of Award

1990

Availability

Article

Degree Name

Doctor of Philosophy (Ph.D.)

Department

Applied Marine Physics/Ocean Engineering

First Committee Member

Tokuo Yamamoto, Committee Chair

Abstract

This dissertation is intended as a complete statement of the Bottom Shear Modulus Profiler method. By measuring the response of a quasi-elastic seabed to the pressure forcing of surface gravity (water) waves, the seabed shear modulus versus depth profile can be extracted by solving an Inverse problem. Using semi-empirical sediment models, estimates of porosity, and shear and compressional wave speeds can be directly extracted from the shear modulus profile. The forward and inverse problems are formulated and numerically investigated. Estimates of uncertainty and resolution in the inversion result are presented. Extensions are made to the basic shear modulus inversion that enable calculation of the seabed frame-loss, wave damping, and seabed anisotropy. However, these extensions are found to be impractical when applied to real ocean data. A complete description of the experimental equipment and procedures is given, along with a discussion of Ocean Bottom Seismometer/seabed coupling. Shallow burial of the OBS housing is found to be necessary, based on experimental data quality improvements for buried instruments. The extensive data analysis algorithms are presented and discussed. Finally, a number of experimental results are presented to demonstrate the method from start to finish. The final results are favourably compared to independent, conventional sediment profiling methods and shear wave refraction experiments.

Keywords

Geophysics; Physical Oceanography; Engineering, Marine and Ocean; Remote Sensing

Link to Full Text

http://access.library.miami.edu/login?url=http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:9032063