Fault Evaluation Study Marysville Lake Project Parks Bar Alternate Yuba River California Butte Yuba Nevada And Placer Counties California

The purpose of the study was threefold: (1) To determine if there had been any surface cracking or faulting within the project area related to the Oroville earthquake sequence; (2) to investigate structures associated with the Swain Ravine and other lineaments and to determine the relationship between them and the 1975 faulting that occurred on the Cleveland Hill fault; and (3) to determine if there has been recent seismic activity within the project area. The study included a comprehensive review of geological reports and maps of the region; the use of data from interpretation of vertical and low-sun-angle aerial photographs; sidelooking airborne radar (SLAR) and Earth Resources Technology Satelite (ERTS) imagery; the compilation of data collected by other agencies investigating the Oroville earthquake and regional tectonics; reconnaissance geological field mapping throughout the regional shear zone; detailed mapping in the project area; and subsurface exploration of the Swain Ravine lineament by trenching.