Publication Date

8-2015

Date of Final Oral Examination (Defense)

5-15-2015

Type of Culminating Activity

Thesis

Degree Title

Master of Science in Geophysics

Department

Geosciences

Supervisory Committee Chair

Lee M. Liberty, Ph.D.

Supervisory Committee Member

Paul Michaels, Ph.D.

Supervisory Committee Member

John Bradford, Ph.D.

Abstract

Determining how a building site will respond to earthquake ground shaking plays a critical role in proper construction practices. One critical constraint on how a site responds is the near surface shear wave seismic velocity distribution. One commonly used method for indirectly estimating shear wave velocities is Multichannel Analysis of Surface Waves (MASW), which utilizes a spread of vertical geophones to measure Rayleigh wave dispersion. With this approach, phase velocity vs. frequency dispersion curve picks can be used to estimate shear wave velocities with depth. I investigate the use of two (vertical and horizontal inline) component seismic signals to record the elliptical Rayleigh wave motion for improved constraints on the phase velocity vs. frequency relationship in a process I term Multi-Component Analysis of Surface Waves (MCASW). Using MCASW allows me to better constrain Rayleigh wave dispersion at lower frequencies, leading to more accurate estimates of shear wave velocities at greater depths compared to the traditional MASW approach. I can also use multiple seismic components to determine particle motions to identify and remove select Rayleigh wave modes. I show that my polar mute approach leads to a further improvement of shear wave velocity estimates from Rayleigh wave signals.

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