Date of Award
Master of Science
Alan E. Kehew, Ph.D.
William A. Sauck, Ph.D.
Robb Gillespie, Ph.D.
Geology, glacial, geophysics, horizontal to vertical spectral ratio (HVSR), tunnel valley
Masters Thesis-Open Access
This study utilizes the Horizontal to Vertical Spectral Ratio (HVSR) technique to map bedrock topography in the Portage and Schoolcraft NW quadrangles, Kalamazoo Co., MI, looking for buried bedrock valleys. Glacial sediment-landform assemblages dominate the study area, due to multiple advances of the Laurentide Ice Sheet (LIS). Tunnel valleys, which are one type of buried valley, are eroded by subglacial meltwater and commonly filled with the coarser varieties of glacial outwash, making them potential aquifers. The HVSR technique measures the ratio of horizontal to vertical ground motion, excited by ambient seismic noise, resulting in a peak at the resonance frequency. I took 308 HVSR recordings of resonance frequency and used these values to calculate sediment thickness. This was accomplished with a calibration curve generated at 13 control wells, using the power law regression equation Z = af0b. The constants a and b are 101.36 and -1.46. Bedrock relief was determined to be 370 ft (112 m), including three bedrock valleys. One of these valleys is interpreted to be a Saginaw Lobe tunnel valley, due to its steep relief, surface expression, and orientation parallel to Saginaw Lobe flow direction. The two other valleys are interpreted to be the remnants of a pre-glacial drainage network. All three valleys contain several hundred feet of glacial drift, which may contain potentially valuable aquifers.
Seiderman, Benjamin B., "Mapping Bedrock Topography of the Portage and Schoolcraft NW 7.5’ Quadrangles, Kalamazoo Co. MI, Using the HVSR Passive Seismic Method" (2018). Master's Theses. 3401.