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:
surface displacements caused by phenomena other than tectonic phenomena have been confused with tectoni cally induced faulting. Such features include faults on which the last displacement was induced by glaciation or deglaciation; collapse structures, such as found in karst terrain; and growth faulting, such as occurs in the Gulf Coastal Plain or in other deep soil regions sub ject to extensive subsurface fluid withdrawal. Glacially induced faults generally do not represent a deep-seated seismic or fault displacement hazard be cause the conditions that created them are no longer present. However, residual stresses from Pleistocene glaciation may still be present in glaciated regions, al though they are of less concern than active tectonically induced stresses. These features should be investigated with respect to their relationship to current in situ stresses. The nature of faults related to collapse features can usually be defined through geotechnical investigations and can either be avoided or, if feasible, adequate engi neering fixes can be provided. Large, naturally occurring growth faults as found in the coastal plain of Texas and Louisiana can pose a surface displacement hazard, even though offset most likely occurs at a much less rapid rate than that of tec "tonic faults. They are not regarded as having the capac ity to generate damaging vibratory ground motion, can often be identified and avoided in siting, and their dis placements can be monitored. Some growth faults and antithetic faults related to growth faults are not easily identified; therefore, investigations described above with respect to capable faults and fault zones should be applied in regions where growth faults are known to be present. Local human-induced growth faulting can be monitored and controlled or avoided. . If questionable features cannot be demonstrated to be of nontectonic origin, they should be treated as tec tonic deformation. 1.165-35 I II f I REFERENCES D.1 Electric Power