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:
tude (Ref. 14), "* Slip rate versus magnitude (Ref. 16). When such correlations as References 10-16 are used, the earthquake potential is often evaluated as the mean of the distribution. The difficult issue is the evalu ation of the appropriate rupture dimension to be used. This is a judgmental process based on geological data for the fault in question and the behavior of other re gional fault systems of the same type. The other elements of the. recurrence model are generally obtained using catalogs of seismicity, fault slip rate, and other data. In some cases, it may be ap propriate to use recurrence models with memory. All the sources of uncertainty must be appropriately mod eled. Additionally, the phenomenon of temporal clus tering should be considered when there is geological evidence of its past occurrence. 2.3.3 For sites near subduction zones, such as in the Pacific Northwest and Alaska, the maximum mag nitude must be assessed for subduction zone seismic sources. Worldwide observations indicate that the larg est known earthquakes are associated with the plate in terface, although intraslab earthquakes may also have large magnitudes. The assessment of plate interface earthquakes can be based on estimates of the expected dimensions of rupture or analogies to other subduction zones worldwide. 3. PROBABILISTIC SEISMIC HAZARD ANALYSIS PROCEDURES A PSHA should be performed for the site as it al lows the use of multiple models to estimate the likeli hood of earthquake ground motions occurring at a site, and a PSHA systematically takes into account uncer tainties that exist in various parameters (such as seismic sources, maximum 'earthquakes,. and ground motion attenuation). Alternative hypotheses areý con sidered in a quantitative fashion in a PSHA. Alterna tive hypotheses can also be used to evaluate the sensi tivity of the hazard to the uncertainties in the significant parameters and to identify the relative contribution of each seismic source to the hazard.