Veterans Affairs Medical Center

Ninyo & Moore performed a Refraction Microtremor (ReMi) survey during a preliminary design geotechnical evaluation for the proposed Veterans Affairs Medical Center. The survey was performed to obtain an average soil shear wave velocity and to evaluate the seismic Site Class as described in the International Building Code. Data was collected to a depth of approximately 100 feet using a geophone array (line) and a 24 channel seismograph with twenty 4.5-Hertz P-wave geophones spaced approximately 20 feet apart. Ambient noise (microtremors) was recorded for a total period length of 16.38 seconds with a sampling interval of 2,000 microseconds. The one-dimensional shear wave velocity structure and average shear wave velocity was evaluated to a depth of approximately 100 feet. A Multichannel Analysis of Surface Waves (MASW) survey was also performed to further evaluate the average soil shear wave velocity for the site. The findings of the ReMi survey were provided in a preliminary report presenting our findings, conclusions and geotechnical design recommendations, including a Seismic Site Class rating.