Several different seismic methods are used in geophysical surveys. Seismic refraction uses P- and S-wave energy to map vertical and lateral subsurface changes. Multi-channel Analysis of Surface Waves (MASW) is a nondestructive seismic method used to evaluate the shear-wave velocity distribution and arrangement of overburden soil deposits and bedrock. The Spectral Analysis of Surface Waves (SASW) method is applied to soil sites to determine the in-place shear wave velocity profile of soil and rock without requiring a borehole. The Seismic Reflection method uses seismic energy to identify geologic boundaries and is used for geotechnical engineering, environmental contamination flow modeling, and groundwater projects. 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. These measurements are then used for the engineering design of structures planned at those locations.