The safe siting of nuclear power plants requires knowledge of foundation conditions and faulting. Geophysical surveys and measurements are necessary to provide needed data in the early stages of a siting program, in order to supplement geologic studies. Later, detailed licensing studies may require additional geophysical measurements to supplement geotechni-cal engineering studies.

Seismic methods are most commonly used for exploring localized geologic and foundation conditions at and near a plant site; gravity and magnetic measurements are often helpful in regional geologic studies.

Other geophysical exploration techniques are usually reserved for specialized applications such as the search for subsurface cavities, determination of stratigraphy, slope stability studies, hydrogeology, and locating construction materials. Special seismic techniques are employed to determine dynamic elastic properties.