Probable Maximum Precipitation The greatest amount of precipitation for a given duration meteorologically
possible for a given size storm area at a particular location at a particular time of year, with no allowance made
for long-term climatic trends.
Probabilistic Method A technique which uses distributions of parameters (including uncertainty and
randomness) to perform an analysis. Results are expressed in terms of probabilistic distributions which
Response Spectrum A curve calculated from an earthquake accelerogram that gives the value of peak response
in terms of acceleration, velocity, or displacement of a damped linear oscillator (with a given damping ratio)
as a function of its period (or frequency) of vibration. For design purposes, a set of response spectra are
usually generated for different damping ratios.
River Mile Number of miles to the mouth of a river along the course of the river.
Seismic Sources Portions of the earth that have a potential for abrupt releases of energy in the earth's
lithosphere, or to cause earthquakes. Seismic sources may include a region of diffuse seismicity (seismotectonic
province) and/or a well-defined tectonic structure which can generate both earthquakes and ground
Seismogenic crust Is a portion of the earth's crust capable of generating earthquakes.
Site The area comprising or within a DOE jurisdictional unit with one or more DOE facilities that can be
represented by the same natural phenomena hazards.
Stage Elevation above some arbitrary zero datum of the water surface at a gauging station.
Structures, Systems, and Components (SSCs)
Structure is an element, or a collection of elements to provide support or enclosure such as a
building, free standing tank, basins, dikes, or stacks.
System is a collection of components assembled to perform a function such as piping, cable
trays, conduits, or HVAC (Heating, Ventilation and Air Conditioning).
Component is an item of equipment such as a pump, valve, or relay, or an element of a larger
array such as a length of pipe, elbow, or reducer.
Subsidence The settlement or sinking of surficial geological materials on a regional or local scale.
Surface Deformation Distortion of soils or rocks at or near the ground surface by the processes of folding and
faulting as a result of various earth forces. Tectonic surface deformation is associated with earthquake
Surface Faulting Differential ground displacement at or near the surface caused directly by fault movement
and is distinct from non tectonic types of ground disruptions, such as landslides, fissures, and craters.
Tornado Intensity Tornado intensity is generally represented by the Fujita scale. This scale, now routinely
used by the National Weather Service is generally referred to as the F-scale. The F-scale is a simple method