Crosshole Seismic (CS) and Downhole Seismic (DS) tests are performed on soil and rock sites to measure the in-place shear and compression wave velocity profiles of the soil and rock versus depth. Using these measurements, calculations can then be made of the dynamic soil and rock properties for earthquake design analyses for structures (per the USB), liquefaction potential studies, site development and dynamic machine foundation designs. The parameters that can be determined include Poisson’s ratios as well as shear and Young's moduli. In addition, the material damping can be estimated from CS test results. The CS is a cross-hole test that requires at least two boreholes, while DS testing requires only one.