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:
seismic sources are zones within which future earthquakes are likely to occur at the same recurrence rates. Geological, seismological, and geophysical investigations provide the information needed to identify and characterize source parameters, such as size and geometry, and to estimate earthquake recurrence rates and maximum magnitudes. The amount of data available about earthquakes and their causative sources varies substantially between the Western United States (west of the Rocky Mountain front) and the Central and Eastern United States (CEUS), or stable continental region (SCR) (east of the Rocky Mountain front). Furthermore, there are varia tions in the amount and quality of data within these regions. In active tectonic regions there are both capable tectonic sources and seismogenic sources, and be cause of their relatively high activity rate they may be more readily identified. In the CEUS, identifying seismic sources is less certain because of the difficul ty in correlating earthquake activity with known tec tonic structures, the lack of adequate knowledge about earthquake causes, and the relatively lower ac tivity rate. However, several significant tectonic structures exist and some of these have been inter preted as potential seismogenic sources (e.g., the New Madrid fault zone, Nemaha Ridge, and Meers fault). In the CEUS there is no single recommended pro cedure to follow to characterize maximum magni tudes associated with such candidate seismogenic sources; therefore, it is most likely that the deter mination of the properties of the seismogenic source, whether it is a tectonic structure or a seismotectonic province, will be inferred rather than demonstrated by strong correlations with seismicity or geologic data. Moreover, it is not generally known what rela tionships exist between observed tectonic structures in a seismic source within the CEUS and the current earthquake activity that may be associated with that source. Generally, the observed