This project addresses the lessons learned from the 17 October 1989 Northern California (Loma Prieta) earthquake. Local soil/geologic conditions can modify incoming earthquake strong-motions wave trains, causing them to be more damaging. It is well accepted that this effect occurred during the Loma Prieta earthquake. Much can be learned about site-specific seismic response using the wealth of strong-motion data recorded during this earthquake. But in order to understand the observed seismic response, a necessary first step is to define the area's stratigraphy as precisely as possible. This is the objective of this research program. This project seeks to obtain and to analyze all available data on the stratigraphy of the Pleistocene fill, the depth to the basement rock, and to tabulate all measured physical properties of the Pleistocene units for correlation with expectable ranges in velocity propagation. The aim is to prepare precise stratigraphic fence diagrams, unit isopach maps, and to tabulate physical properties and downhole testing data for each geologic unit penetrated. These data form a first step for other studies, such as in defining the seismic response for the Oakland-Alameda Bay Bridge area.
