Document: NRC Regulatory Guide
Document ID: 46b2c829-ce4c-4a6a-8a01-908725558ffe
Document Type: regulatory_guide
Title: Volcanic Hazards Assessment for Proposed Nuclear Power Reactor Sites + HISTORY - HISTORY 03/2020 – DG-4028-Proposed New Guide
Source: NRC Regulatory Guide Division 4
Source URL: https://www.nrc.gov/docs/ML2000/ML20007D621.pdf
Revision Date: 2023-06
Chapter: 
Section ID: RG-4.26
CFR Part: 
CFR Title: 

Content:
r buried or eroded deposits in the region of interest and evaluate the uncertainties that such buried or eroded deposits represent in the appropriate hazard analyses (e.g., Wang and Bebbington, 2012). Evaluating the completeness of the geologic record often requires complex investigation and should be undertaken early in the volcanic hazards assessment (e.g., through the SSHAC process) to allow for development of an appropriate technical basis to support ensuing analyses. Insights from the tectono-magmatic model should be used to consider whether the timing and characteristics of past events appropriately represent potential future events in the region of interest. In many volcanic systems, the record of past events (and associated uncertainties) provides an appropriate basis to consider the range of potential future events. Trends in this record also likely provide information on increases or decreases in the timing or magnitude of future events, which would need to be considered in the volcanic hazards assessment. Nevertheless, some volcanic systems have the potential to evolve though time in ways that are not consistent with the past patterns of activity. For example, spatial patterns might make an abrupt shift due to recent changes in local accommodation of tectonic stresses, or the potential for large-volume explosive eruptions might be significantly lower due to significant changes in magma system processes (e.g., Christiansen et al., 2007). The tectono-magmatic model provides an important framework to develop a technical rationale for how past patterns of activity should or should not be projected to future patterns. Step 2: Screen Volcanic Hazards After determining which Quaternary volcanoes in the region of interest are consistent with the tectono-magmatic model, the characterization studies should focus on developing sufficient information to determine the maximum credible distance that potentially hazardous volcanic phenomena can travel from the volcanic