New Constraints on Strain Partitioning Across Southern California's Diffuse Plate Boundary

Geologic observations provide an important lens to objectively view the natural world and contextualize the processes that have and continue to shape Earth's brittle crust. As a result, many geologic and geophysical tools have been developed. This dissertation uses high-resolution sub-bottom and multi-channel seismic data to observe sequence stratigraphic and morphologic signatures of deformation encoded into Southern California and its offshore component, the California Continental Borderland (CCB). Using geophysical tools, this dissertation first investigates the vertical displacement history of the Inner California Borderland (ICB) using marine terraces. By Imaging marine terraces with sub-bottom profilers offshore San Clemente and Santa Catalina Islands and contextualizing them with legacy on and offshore data, it is possible to extend our current Quaternary understanding of the vertical displacement history of the ICB through to the Middle Miocene. In addition, this model provides a framework for the formation of disputed marine terraces observed at depths deeper than the Last Glacial Maximum (LGM). Second, I conducted a seismic stratigraphic analysis of the Catalina Basin, one of the many basins that make up the ICB, to constrain the late Cenozoic evolution of the region and put into context basin-wide markers of historic relative sea level with regional geology. Third, this dissertation outlines the use of the Kongsberg SBP 29, recently installed on the R/V Sally Ride in June of 2021, to image and characterize active deformation within the Outer California Borderland (OCB). The OCB, a relatively under-surveyed region within the CCB, has not been widely recognized as accommodating active deformation. Interpretation of the high-resolution sub-bottom data is constrained by proximal Ocean Drilling Project cores. As a result, it is possible confidently report that the Ferrelo Fault has been active within the last 1,000 years, accommodating Pacific/North American relative strain. Lastly, the novel use of a sub-bottom profiler is employed, typically a marine and or lacustrine instrument, to image onshore deformation along an unlined section of the All-American Canal. This survey images deformation within the Imperial Valley, along the Imperial, Dixieland, and Michoacán Faults, in an area where anthropogenic activity has otherwise made direct observations of surface deformation difficult