Master of Science (MS), Bowling Green State University, 2020, Geology

The purpose of this study is determining a potential correlation between soil moisture and burn severity as well as examining potential correlations between slope, elevation, wind speed, wind direction and Normalized Difference Vegetation Index (NDVI) value and burn severity within the Mendocino Complex Fire, California, which occurred in 2018. A time-series of the difference Normalized Burn Ratio (dNBR), the difference between pre- and intra-fire NBR values, was calculated via Sentinel-2, soil moisture was mapped using SMAP, and the Digital Elevation Model (DEM) from ASTER was used to derive elevation and slope values. The imagery was obtained from USGS and USDA websites. Images were processed and reprojected to the same spatial resolution (60 m) and projection (UTM Zone 10N, WGS-87). dNBR imagery was subdivided in newly burned areas for each consecutive day for ten days from 29 July 2018 to 31 August 2018. The findings suggested that there was no strong correlation trend consistently found over the proposed period of time between dNBR values and soil moisture content (R ≈ -0.20 to 0.39), slope (R ≈ -0.35 to 0.46), elevation (R ≈ -0.24 to 0.56), wind speed (R ≈ -0.15 to 0.36), and wind direction (R ≈ -0.42 to 0.24). However, a positive correlation between NDVI values and dNBR values was found to be strong and consistent (R ≈ -0.48 to 0.57). This implies that burn severity increased more significantly and frequently with NDVI, a surrogate for vegetation biomass and leaf area index. It can be surmised that soil moisture must reach some higher values before having a possible impact upon burn severity. Considering that the summer of 2018 was one of the warmest and driest summers in the study area's recent history, soil moisture content was relatively low while, simultaneously, vegetation was dry and more prone to burning.

Committee: Anita Simic Milas Ph.D. (Advisor); Yuning Fu Ph.D. (Committee Member); Ganming Liu Ph.D. (Committee Member) Subjects: Environmental Geology; Geography; Geology; Remote Sensing; Statistics

Master of Science (MS), Wright State University, 2019, Earth and Environmental Sciences

This study focuses on northern Terre Haute, Indiana, where seven 2D seismic reflection time sections were collected by CountryMark and donated to Wright State University. Geologically, the area is on the eastern margin of the Illinois Basin. Two of these seismic lines display significant relief along a continuous, high-amplitude horizon approximately 180 milliseconds in two-way traveltime depth. This horizon was previously interpreted by CountryMark to be a Silurian reef core of the type common in this region of the Illinois Basin; however, other seismic lines within the data set display no relief. Furthermore, borehole logs within the area show no such relief at the equivalent depth of around 1700 feet. Therefore, the apparent structural high is an artifact within the two seismic lines, and can be called velocity pull-up. Various analyses were conducted to examine the causes of this velocity pull-up. The near-surface, within this region, contains many surfaces that may give rise to a velocity pull-up, including (1) the layer of weathered Pennsylvanian bedrock; (2) the Mississippian-Pennsylvanian Unconformity; and (3) an unconformity within Pennsylvanian section. It is possible that each of these surfaces could have enough relief to induce the observed velocity pull-up, and these possibilities were evaluated utilizing a combined analysis of Bouguer gravity, first-arrival traveltime tomography, passive seismic, and well log correlation. These multiple analyses show there is no Silurian reef core but a more complex velocity-inducing feature from a combination of the Mississippian-Pennsylvanian Unconformity and a shallower paleovalley fill.

Committee: Ernest C. Hauser Ph.D. (Committee Chair); Doyle R. Watts Ph.D. (Committee Member); David F. Dominic Ph.D. (Committee Member) Subjects: Geographic Information Science; Geology; Geophysical; Geophysics

Master of Science, University of Akron, 2014, Geology-Geophysics

Ground penetrating radar (GPR), electrical resistivity and seismic refraction surveys were used to image possible buried sinkholes and identify potential areas of subsidence in the shallow paleokarst surface of the Columbus Limestone at Ohio Caverns in Champaign County, Ohio. A buried sinkhole, incipient sinkholes and a possible buried cave passage spatially correlated with orthoimagery and surface evidence of subsidence. Correlations were established by using GIS software overlaying a structure-contour map of the paleokarst, as determined by GPR data, over orthoimagery of the area. Wenner and dipole-dipole electrical resistivity surveys suggest regions of lower resistivity surrounded by higher resistivity are associated with suspected subsidence. Refraction seismic data, collected along the same transect as the resistivity surveys, also correlated with an area of depression in the region of a suspected sinkhole. The seismic velocities from the refraction survey indicated lower depths for the clay soil and Ohio Shale contact and also the boundary between the Ohio Shale and the Columbus Limestone. Remote sensing using electrical resistivity, GPR and seismic refraction techniques successfully imaged the stratigraphy of the area and suggest other areas of incipient sinkhole formation.

Committee: David Steer Dr. (Advisor); John Peck Dr. (Committee Member); Ira Sasowsky Dr. (Committee Member) Subjects: Environmental Geology; Geographic Information Science; Geological; Geology; Geophysical; Geophysics