David Dominic (Committee Member), Ernest Hauser (Advisor), Doyle Watts (Committee Member)
Master of Science (MS)
Multi-Channel Analysis of Surface Waves (MASW) was performed on data collected at four locations previously occupied by 3-component broadband seismometers. The goal was to use MASW to define the velocity structure and depth to bedrock locally, and to examine how well the calculated surface layer resonance derived from this velocity structure compares with the surface layer resonance observed in the passive seismic data at that site. At the test site east of Xenia, Ohio, a clear change in lithology (glacial drift to limestone bedrock) on each of the 1-D MASW profiles is indicated by a substantial change in shear-wave velocity (Vs) at depth and is consistent with the depth to bedrock from water wells in the area. Both water wells and the MASW results indicate that depth to bedrock increases significantly to the east along Federal Rd toward a pre-glacial buried valley. The calculated resonant frequency of the glacial drift surface layer, using the fundamental mode equation, compares very well to the peak frequency expressed in the horizontal to vertical ratio (H/V) of passive seismometer data at the same locations. A clear and distinct surface layer resonance is evident in most passive seismic data of this study, although one seismometer station expressed a double peak suggesting very local distinct variations in drift thickness such as expected at a bedrock ledge or a buried ravine or small valley. One practical conclusion of this study is that in settings of high velocity contrast between a surface layer and bedrock, where glacial drift overlies limestone bedrock, by determining the Vs of the drift using MASW, one can use the H/V peak frequency of 3-component seismic data to calculate the regional depth to bedrock values in locations where Vs is consistent.
Department or Program
Department of Earth and Environmental Sciences
Year Degree Awarded
Copyright 2012, all rights reserved. This open access ETD is published by Wright State University and OhioLINK.