Document: NRC Regulatory Guide
Document ID: cfc61809-5745-460f-8a26-13c168659924
Document Type: regulatory_guide
Title: Identification and Characterization of Seismic Sources and Determination of Safe Shutdown Earthquake Ground Motion
Source: NRC Regulatory Guide Division 1
Source URL: https://www.nrc.gov/docs/ML0037/ML003740084.pdf
Revision Date: 2023-06
Chapter: 
Section ID: RG-1.165
CFR Part: 
CFR Title: 

Content:
ances derived from a deaggregation anal ysis of the median estimate of the PSHA. Earthquake Recurrence - Earthquake recurrence is the frequency of occurrence of earthquakes having vari ous magnitudes. Recurrence relationships or curves are developed for each seismic source, and they reflect the frequency of occurrence (usually expressed on an annual basis) of magnitudes up to the maximum, in cluding measures of uncertainty. Intensity - The intensity of an earthquake is a meas ure of vibratory ground motion effects on humans, on human-built structures, and on the earth's surface at a particular location. Intensity is described by a numeri cal value on the Modified Mercalli scale. Magnitude - An earthquake's magnitude is a meas ure of the strength of the earthquake as determined from seismographic observations. Maximum Magnitude -The maximum magnitude is the upper bound to recurrence curves. Nontectonic Deformation - Nontectonic deforma tion is distortion of surface or near-surface soils or rocks that is not directly attributable to tectonic activity. Such deformation includes features associated with subsidence, karst terrane, glaciation or deglaciation, and growth faulting. Safe Shutdown Earthquake Ground Motion (SSE) -Th/o/SSE is the vibratory ground motion for which certain structures, systems, and components are de signed, pursuant to Appendix S to 10 CFR Part 50, to remain functional. The SSE for the site is characterized by both horizon tal and vertical free-field ground motion response spec tra at the free ground surface. Seismic Potential - A model giving a complete de scription of the future earthquake activity in a seismic source zone. The model includes a relation giving the frequency (rate) of earthquakes of any magnitude, an estimate of the largest earthquake that could occur un der the current tectonic regime, and a complete descrip tion of the uncertainty. A typical model used for PSHA is the use of a truncated exponential model for the mag nitude