Compressional and shear wave tests were conducted on the upper thrust sheet of the low angle Little Salmon thrust fault. The study was conducted on the campus of the College of the Redwoods. The campus is located approximately 8 miles south of Eureka and 24 miles north-northeast of Cape Mendocino and the Mendocino Triple Junction (MTJ) in Northern California. The MTJ is the point of transition from strike-slip faulting of the San Andreas transform system to low-angle reverse (thrust) faulting and folding associated with the convergent margin of the Cascadia Subduction Zone. The campus is located on the southwest limb of the Humboldt Hill anticline, one of the folds in the fold and thrust belt. The Little Salmon fault zone is a low angle thrust fault that day lights on the south side of the campus and then projects underneath striking northwest and dipping northeast. A boring was drilled down to the fault plane located at a depth of 200 ft. in the upper thrust block to develop a mode1 of the stratification as well as the material properties. The boring also revealed the trunk of a redwood tree located at a depth of 180 feet. Results of compressional and shear wave velocities as a function of depth that were determined using an downhole geophysical technique. Results indicated two shear wave velocity units. Unit 1 was from 0 to 120 ft. with a shear wave velocity ranging from 950- 1400 fps. Unit 2 ranged from 120 to 190 ft. with a shear wave velocity ranging from 2300 to 2600 fps. Compression wave velocity measurements obtained from the same test boring also depict a change in velocity in the 100 to 120 foot range. A response spectra was generated based on this in-situ mode1 using SHARE91 and compared against one developed using the Boore, Joyner and Fumal empirical model
