Remote-sensing data for studies of nuclear power plant sites are acquired by aerial surveys and satellite programs and include satellite photography (Landsat and Skylab); conventional black-and-white, color, and color infrared photography; thermal infrared imagery; radar imagery (side-looking airborne radar); and airborne geophysical surveys, such as aeromagnetic and aeroradiometric surveys.

In general, existing data from such surveys are relatively inexpensive to obtain and offer a synoptic overview of the area, provide a large amount of information for the scale involved, and afford a technique of sampling that does not disturb the sample.

In current methods of analysis, the photography, images, and maps are brought to a common scale, and existing structural geologic data are compared with a new data set, usually in the form of lineaments. The field investigations that follow include reconnaissance and detailed geologic investigations of the lineaments to detect evidence of faulting; then ground geophysical surveys, boreholes and trench studies are made. These field investigations add "ground data" to the remote-sensing base and aid in evaluating the significance of any geologic structure so defined.

Two examples of recent fault studies for nuclear power plant sites, one conducted in the Virginia Piedmont tectonic province and the other in the Maryland Coastal Plain province, illustrate the potential value of remote sensing in the site selection process. When correlation of geologic maps with the several remote-sensing techniques is undertaken early in the planning stages of the siting study, it is possible to locate the nuclear power plant away from potentially hazardous geologic structures or to avoid such ambiguous geologic features as are impossible to adequately define in terms of site safety.