NUREG/CR-7238 Guidance Document: Conducting Paleoliquefaction Studies for Earthquake Source Characterization Office of Nuclear Regulatory Research AVAILABILITY OF REFERENCE MATERIALS IN NRC PUBLICATIONS NRC Reference Material Non-N RC Reference Material As of November 1999, you may electronically access Documents available from public and special technical NUREG-series publications and other NRC records at libraries include all open literature items, such as books, the NRC's Public Electronic Reading Room at journal articles, transactions, Federal Register notices, http://www. nrc. gov/reading-rm.html. Publicly released Federal and State legislation, and congressional reports. records include, to name a few, NUREG-series Such documents as theses, dissertations, foreign reports publications; Federal Register notices; applicant, and translations, and non-NRC conference proceedings licensee, and vendor documents and correspondence; may be purchased from their sponsoring organization. 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Although references to material Neither the U.S. Government nor any agency thereof, nor found on a Web site bear the date the material was any employee, makes any warranty, expressed or accessed, the material available on the date cited implied, or assumes any legal liability or responsibility for may subsequently be removed from the site. any third party's use, or the results of such use, of any information, apparatus, product, or process disclosed in this publication, or represents that its use by such third party v.ouldnot infringe privately owned rights. SR-CR 08/2016 NUREG/CR-7238 Guidance Document: Conducting Paleoliquefaction Studies for Earthquake Source Characterization Manuscript Completed: January 2017 Date Published: January 2018 Prepared by: M. Tuttle1 L. Wolf2 P. Mayne3 K. Dyer-Williams4 R. Lafferty5 1 M. Tuttle & Associates, P.O. Box 345, Georgetown, ME 04548 2 Auburn University, Geosciences, Auburn, AL 36849 3 Georgia Institute of Technology, Civil and Environmental Engineering, Atlanta, GA 30332-0355 4 VanLeen Associates, P.O. Box 156, Columbia, MD 21045 5 Lafferty-Hess Consultants, 16400 Sigmond Lane, Lowell, AR 72745 Sarah Tabatabai, NRC Project Manager Of fice of Nuclear Regulatory Research ABSTRACT Destructive earthquakes, both recent and historical, demonstrate the critical need for paleoliquefaction data to assist with the assessment of the potential for damaging earthquakes around the world. Paleoliquefaction studies, along with other paleoseismic studies such as fault studies, supplement seismicity studies and provide information about the long-term behavior of earthquake sources. Paleoliquefaction studies focus on soft-sediment deformation features, including sand blows and sand dikes, and related ground failures that result from large earthquakes. Most paleoliquefaction studies have been conducted in intraplate geologic settings, but a few such studies have been carried out in interplate settings as well. Paleoliquefaction studies have provided valuable information about timing, location, and magnitude of large paleoearthquakes, particularly those with moment magnitude, M, greater than 6, during the past 50,000 years. Although the results of paleoliquefaction studies have greatly increased the understanding of seismic hazards in a few regions where Holocene (0.01 million years ago, or Ma, to present) and Late Pleistocene (0.126 to 0.01 Ma) age deposits occur, the specific type, level of detail, and quality of paleoliquefaction data vary from one study area to another. This variation is due in part to the lack of standardized procedures for paleoliquefaction studies. There is also a shortage of qualified and experienced paleoliquefaction experts and few comprehensive resources for new investigators or regulators interested in obtaining results from paleoliquefaction studies for characterization of earthquake sources. In order to overcome some of the current deficiencies and advance the field of paleoliquefaction, this document provides detailed guidance for conducting paleoliquefaction studies that will generate high-quality paleoliquefaction data for use in seismic source characterization and seismic hazard assessment. Intended as a comprehensive resource for investigators and regulators interested in the field of paleoliquefaction, this report includes background information on earthquake-induced liquefaction and related ground failures and the resulting soft-sediment deformation features that may be preserved in the geologic record, relevant information derived from the disciplines of geology, geophysics, and geotechnical engineering, an extensive bibliography, and recommendations for future research. iii FOREWORD The U.S. Nuclear Regulatory Commission (NRC) requires an evaluation to determine the Safe Shutdown Earthquake Ground Motion (SSE) for a nuclear power plant site as specified in 10 CFR Part 100. A performance based approach to define site-specific earthquake ground motion is one component in the development and evaluation of the SSE. Regulatory Guide 1.208 provides guidance on this performance based approach which implements a probabilistic seismic hazard analysis. The probabilistic seismic hazard analysis is dependent on the characterization of seismic (earthquake) sources, with the key parameters in characterizing seismic sources being their location, timing, and size. The historical record of measured earthquakes is limited; therefore, the study of prehistoric earthquakes is extremely valuable in characterizing seismic sources. The study of prehistoric liquefaction features, paleoliquefaction, is one method used to characterize seismic sources. Regulatory Guide 1.208, A Performance-Based Approach to Define the Site-Specific Earthquake Ground Motion, and the Standard Review Plan for the Review of Safety Analysis Reports for Nuclear Power Plants: LWR Edition (NUREG-0800), Section 2.5.1, provides guidance to license applicants and NRC staff, respectively, on the review of seismic sources. This document provides valuable guidance on how to conduct a paleoliquefaction study and evaluate data with consideration of uncertainties encountered in the various phases of the study for seismic source characterization. This guidance document will be a resource for staff as updates to regulatory and staff guidance are developed on characterizing seismic sources. v TABLE OF CONTENTS ABSTRACT ...............................................................................................................................iii FOREWORD ............................................................................................................................. v LIST OF FIGURES ....................................................................................................................ix LIST OF TABLES ...................................................................................................................xvii EXECUTIVE SUMMARY .........................................................................................................xix