Text

Second Response to Request for Additional Information Dated October 23, 2014, Related to Southeastern Catalog Changes and Seismic Re-Evaluations
	ML15128A332
Person / Time
Site:	Oconee
Issue date:	04/30/2015
From:	Batson S; Duke Energy Carolinas
To:	; Document Control Desk, Office of Nuclear Reactor Regulation
References
	ONS-2015-055
	Download: ML15128A332 (130)
	v • d • e

Scott L.Batson DUKE Vice President Oconee NuclearStation ENERGY, Duke Energy ONOIVP I 7800 Rochester Hwy ONS-2015-055 Seneca, SC 29672 o: 864.873.3274 f 864.873. 4208 April 30, 2015 Scott.Batson@duke-energy.com ATTN: Document Control Desk 10 CFR 50.54(f)

U.S. Nuclear Regulatory Commission Washington, DC 20555 Duke Energy Carolinas, LLC (Duke Energy)

Oconee Nuclear Station, Units 1, 2 and 3 Docket Numbers 50-269, 50-270, 50-287 Renewed License Numbers DPR-38, DPR-47, and DPR-55

Subject:

Second Response to Request for Additional Information dated October 23, 2014, Related to Southeastern Catalog Changes and Seismic Re-Evaluations

References:

1. Duke Energy letter to NRC, Seismic Hazard and Screening Report (CEUS Sites), Response to NRC 10 CFR 50.54(f) Request for Information Pursuantto Title 10 of the Code of Federal Regulations 50.54(f) regardingRecommendations 2.1, 2.3 and 9.3 of the Near-Term Task Force Review of Insights from the Fukushima Dai-ichiAccident,"(for Oconee) dated March 31, 2014 (ADAMS Accession Number ML14092A024)

2. NRC letter, Request for Additional Information Regarding the use of the Revised CEUS Seismic Catalogue, dated October 23, 2014 (ADAMS Accession No. ML14268A516)

3. Duke Energy letter to NRC, Response to the NRC's Request for Additional Information dated October 23, 2014, Related to Southeastern Catalog Changes and Seismic Re-Evaluations, dated October 23, 2014 (ML14325A584)

Ladies and Gentlemen, Duke Energy submitted a Seismic Hazard and Screening Report (CEUS Sites) for Oconee Nuclear Station (ONS) on March 31, 2014 (Reference 1) pursuant to the NRC's 10 CFR 50.54(f) request associated with Fukushima. The report required changes to be made to the Central and Eastern United States Seismic Source Characterization (CEUS-SSC) for Nuclear Facilities catalog.

By letter dated October 23, 2014 (Reference 2), the NRC submitted a Request for Additional Information (RAI) related to the CEUS-SSC changes. Duke Energy provided a response to the request (Reference 3) which contained one future action. That action was to provide the results of a Senior Seismic Hazard Analysis Committee (SSHAC), Level 2 study to substantiate the catalog changes made for Oconee's Seismic Hazard and Screening Report. The enclosure to this letter provides a copy of the Electric Power Research Institute's (EPRI) SSHAC Level 2 Study as requested by the RAI. It is Duke Energy's understanding that this information will also be published by EPRI at a later date.

0,4o

ONS-2015-055 April 30, 2015 Page 2 This letter does not create or revise a Regulatory Commitment.

Should you have any questions concerning this letter, or require additional information, please contact David Haile at (864) 873-4742.

I declare under penalty of perjury that the foregoing is true and correct. Executed on April 30, 2015.

Sincerely, Scott L. Batson Vice President Oconee Nuclear Station Enclosure Oconee Nuclear Station Units 1, 2, and 3, Duke Energy Response to RAI:

Senior Seismic Hazard Analysis Committee (SSHAC) Level 2 Study

ONS-2015-055 April 30, 2015 cc:

Mr. Victor McCree, Regional Administrator U.S. Nuclear Regulatory Commission - Region II Marquis One Tower 245 Peachtree Center Ave., NE Suite 1200 Atlanta, Georgia 30303-1257 Mr. William Dean, Director, Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission One White Flint North 11555 Rockville Pike Rockville, MD 20852-2738 Mr. Nicholas DiFrancesco, Project Manager (Seismic Walkdowns and Reevaluations)

(by electronic mail only)

U.S. Nuclear Regulatory Commission 11555 Rockville Pike Mail Stop O-13C5 Rockville, MD 20852 Mr. James R. Hall, Project Manager (ONS)

(by electronic mail only)

U.S. Nuclear Regulatory Commission 11555 Rockville Pike Mail Stop O-8B1 Rockville, MD 20852 Jeffery Whited, Project Manager (by electronic mail only)

U.S. Nuclear Regulatory Commission 11555 Rockville Pike Mail Stop O-8B1A Rockville, MD 20852 Mr. Eddy Crowe NRC Senior Resident Inspector Oconee Nuclear Station

Enclosure - SSHAC Level 2 Study ONS-2015-055 April 30, 2015 Enclosure Oconee Nuclear Station Units 1, 2, and 3 Duke Energy Response to RAI:

Senior Seismic Hazard Analysis Committee (SSHAC) Level 2 Study

Enclosure - SSHAC Level 2 Study ONS-2015-055 April 30, 2015 Request for Additional Information Consistent with the request for information issued pursuant to Title 10 of the Code of Federal regulations,Part 50, Section 50.54(o and the SPID guidance, please provide a revised March 2014 seismic hazard reevaluation submittal reflecting the staff endorsed CEUS-SSC (Central and Eastern United States Seismic Source Characterizationfor Nuclear Facilities)Catalog Version 7.0.

Alternatively, to ensure that the regional catalog update made for the Recommendation 2.1 seismic hazard reevaluations of H. B. Robinson, Oconee, and VC Summer plant sites represents the center, body, and range of the technically defensible interpretations, please provide a SSHAC Level 2 study. In addition to providing a detailed description of the catalog update, please describe the scope of the update and whether you also considered the impact of earthquakes in the region since the time period covered by the CEUS-SSC Catalog.

Please include in the response, in table form, control point seismic hazard curves developed using both the currently-endorsed CEUS-SSC catalog as well as the proposed updated regional catalog used for the Recommendation 2.1 seismic hazard reevaluations of H.B. Robinson, Oconee, and VC Summer plant sites.

Oconee Nuclear Station Response (This response addressesthe SSHAC study, the balance of information requested has been provided in a previous submittal.)

For Oconee, Duke Energy elected to exercise the proposed alternate response provided in the RAI and provide a SSHAC Level 21 study of the updated Regional CEUS-SSC Catalog. The required study is provided as an attachment to this enclosure. Please find the following:

EPRI Letter RSM-042115-093 dated April 24, 2015,

Subject:

"SSHAC Level 2 Review of EPRI 1021097 Earthquake Catalog Changes for RIS Earthquakes in the Southeastern U. S. and Earthquakes in South Carolina Near the Time of the 1886 Charleston Earthquake Sequence"

AMEC Foster Wheeler project (# 8515180180) letter dated April 23, 2015

Subject:

"Review of NUREG-2115 Earthquake Catalog with regard to identification of additional Reservoir Induced Seismicity (RIS) earthquakes in the Southeastern United States and locations of earthquakes in South Carolina near the time of the 1886 Charleston, SC earthquake sequence" 1 SSHAC Level 2 relates to "Recommendations for Probabilistic Seismic Hazard Analysis: Guidance on Uncertainty and Use of Experts" through the U.S. Nuclear Regulatory Commission as NUREG/CR-6372

I~ELECTRIC RO E RESEARCH INSTITUTE April 24, 2015 RSM-042115-093 Mr. Jeremy Graham Mr. Robert Keiser Design Engineering Mail Code: EC01T South Carolina Electric and Gas Company Duke Energy Corporation P.O. Box 88, Mail Code 805 526 South Church Street Jenkinsville, South Carolina 29065 Charlotte, NC 28202

Subject:

SSHAC Level 2 Review of EPRI 1021097 Earthquake Catalog Changes for RIS Earthquakes in the Southeastern U.S. and Earthquakes in South Carolina Near the Time of the 1886 Charleston Earthquake Sequence Please find attached an evaluation of the earthquake catalog in EPRI 1021097 (NUREG-2115, DOE/NE-0140) focusing on identification of additional reservoir induced seismicity (RIS) earthquakes in the southeastern U.S. and locations of earthquakes in South Carolina near the time of the 1886 Charleston earthquake sequence. Several RIS events were identified in the catalog and a number of South Carolina earthquakes were evaluated to be Charleston earthquake aftershocks. Further processing of the updated earthquake catalog was performed using the same procedures as in EPRI 1021097 including Magnitude evaluations, declustering, and completeness calculations. The attached evaluation provides a complete description of the earthquakes evaluated and conclusions reached.

A SSHAC Level 2 peer review was performed of the updates to the earthquake catalog in EPRI 1021097 consistent with the criteria in NUREG/CR-6372, Recommendations for ProbabilisticSeismic Hazard Analysis: Guidance on Uncertaintyand Use of Experts, 1997. The peer review did not identify any issues that would require a revision to the Rev 8 catalog submitted by Dr. Youngs in March 2014. Based on the results of the peer review, it is concluded that the Rev 8 CEUS SSC catalog (Youngs, 2014) constitutes an appropriate earthquake catalog for assessing earthquake recurrence rates in the southeastern U.S.

Sincerely, John MRichards Principal Technical Leader Risk and Safety Management Attachment c: Mr. Stuart Lewis, EPRI Mr. Robert Kassawara, EPRI Together ... Shaping the Future of Electricity CHARLOTTE OFFICE 1300 West W.T. Harris Boulevard, Charlotte, NC 28262-8550 USA

704.595.2000

Fax 704.595.2860 Customer Service 800.313.3774

www.epri.com

A ~;1 1)2 On/lr,:

i I amec Project 8515180180 foster John Richards wheeler Electric Power Research Institute, Inc.

1300 West WT Harris Boulevard Charlotte, NC 28262

Subject:

Review of NUREG-2115 Earthquake Catalog With Regard to Identification of Additional Reservoir Induced Seismicity (RIS) Earthquakes in the Southeastern United States and Locations of Earthquakes in South Carolina Near the Time of the 1886 Charleston, SC Earthquake Sequence

Dear Mr. Richards:

At the request of EPRI, Amec Foster Wheeler performed in February and March of 2014 a review of the Central and Eastern United States Seismic Source Characterization (CEUS SSC) earthquake catalog published in NUREG-2115 (EPRI/DOE/NRC, 2012). The review was focused on two issues: (1) identification of additional reservoir induced seismicity (RIS) earthquakes in the southeastern US and (2): locations of earthquakes in South Carolina near the time of the 1886 Charleston, SC earthquake sequence. The catalog review is considered a SSHAC (Budnitz et al., 1997) Level 2 review in that researchers on South Carolina historical seismicity were contacted and provided unpublished information. Based on that review, revisions to the CEUS SSC catalog were recommended and a revised CEUS SSC catalog, Rev 8, was prepared (Youngs, 2014) for use in earthquake recurrence calculations.

More recently, EPRI has requested that the revisions to the NUREG 2115 earthquake catalog proposed in Youngs (2014) be subjected to peer review. Such peer review would constitute a late-stage peer review, which is acceptable under the SSHAC guidance for projects conducted using a Technical Integrator (TI) approach (i.e. SSHAC Levels 1-3). As the CEUS SSC project was a SSHAC Level 3 project, the late-stage peer review is acceptable.

Amec Foster Wheeler engaged two peer reviewers to perform the review. Dr. Martin Chapman has extensive experience in evaluating seismicity in the southeastern portion of the US. Dr.

Richard Quittmeyer has extensive experience in evaluation seismicity for seismic hazard analyses, including being a member of one of the expert teams that developed the EPRI-SOG seismic source model for the CEUS. These two experts performed a peer review of Youngs (2014). Attachment 2 to this memo contains the peer review comments received from Dr.

Chapman and Dr. Quittmeyer. Attachment 3 contains Amec Foster Wheeler's responses, and contains Dr Chapman's and Dr. Quittmeyer's concurrence with the response to their comments. The primary comment received from the reviewers was the need for improved documentation. In response, Amec Foster Wheeler has prepared a revision to the documentation to address the comments of the reviewers. The revised catalog review document is included as Attachment 1 to this letter.

Amec Foster Wheeler Environment & Infrastructure, Inc.

180 Grand Avenue, Suite 1100 Oakland, California 94612-3066 USA Tel (510) 663-4100 Fax (510) 663-4141 amecfw.com

John Richards Electric Power Research Institute, Inc April 23, 2015 Page 2 The peer review did not identify any issues that would require a revision to the Rev 8 catalog submitted by Youngs (2014). Dr. Chapman did identify one additional earthquake that should be classified as RIS. However, it is judged that the impact of one additional RIS earthquake on the assessed earthquake recurrence rates in the southeastern US would be minor and no revision to the Rev 8 CEUS SSC catalog is proposed. Based on the results of the peer review, it is concluded that the Rev 8 CEUS SSC catalog (Youngs, 2014) constitutes an appropriate earthquake catalog for assessing earthquake recurrence rates in the southeastern US.

Sincerely yours, Amec Foster Wheeler Environment & Infrastructure, In Valentina Montaldo Falero Senior Seismologist Principal Seismic Engineer VMF/RY/dc x:\18000s\180180\3000_reports to client\ceus ssc catalogupdate_042315\ceus ssc catalogupdate_04_23_2015.docx Attachments: Attachment 1-Review of EPRI 1021097 Earthquake Catalog for RIS and Charleston Aftershock Locations in the Southeastern United States, Rev 1 Attachment 2-Reviews by Dr. Martin Chapman and Dr. Richard Quittmeyer Attachment 3-Amec Foster Wheeler's Responses to Review Comments Attachment 4-Concurrence letters from Dr. Martin Chapman and Dr. Richard Quittmeyer REFERENCES Budnitz, R.J., Apostolakis, G., Boore, D.M., Cluff, L.S., Coppersmith, K.J., Cornell, C.A., and Morris, P.A., 1997. Recommendations for Probabilistic Seismic Hazard Analysis:

Guidance on Uncertainty and Use of Experts, Report NUREG/CR-6372, Lawrence Livermore National Laboratory, sponsored by the U.S. Nuclear Regulatory Commission, U.S. Department of Energy, and Electric Power Research Institute.

Electric Power Research Institute, U.S. Department of Energy, and U.S. Nuclear Regulatory Commission (EPRI/DOE/NRC), 2012, Technical Report: Central and Eastern United States Seismic Source Characterization for Nuclear Facilities, published as NUREG-2115 by the U.S. Nuclear Regulatory Commission.

Youngs, R., 2014, Review of EPRI 1021097 Earthquake Catalog for RIS Earthquakes in the Southeastern US and Earthquakes in South Carolina Near the Time of the 1886 Charleston Earthquake Sequence." Report transmitted by EPRI letter on March 5, 2014 by J. Richards.

Amec Foster Wheeler

amec foster wheeler ATTACHMENT 1 Review of EPRI 1021097 Earthquake Catalog for RIS and Charleston Aftershock Review of EPRI 1021097 Earthquake Catalog for RIS and Charleston Aftershock Locations in the Southeastern United States Revision History March, 2014 Original Issue April, 2015 Revision 1

TABLE OF CONTENTS Page PART 1 IDENTIFICATION OF ADDITIONAL RESERVOIR INDUCED SEISMICITY (RIS)

EARTHQUAKES IN THE SOUTHEASTERN U.S .................................................................. 3 1.1 R eferences ........................................................................................................ .....3 1.2 R eview R esults ........................................................................................................ .. 4 1.3 Seismicity within 100 km of NPPs in the Southeastern U.S .................................... 13 1.3.1 NPPs Located on Lakes and Reservoirs .......................................................... 14 1.3.2 NPPs Located on R ivers ................................................................................... 23 1.4 Summary of Assessments of Additional RIS ........................................................... 27 PART 2 EARTHQUAKES IN SOUTH CAROLINA NEAR THE TIME OF THE 1886 CHARLESTON, SC, EARTHQUAKE SEQUENCE ................................................................ 31 2 .1 R e fe re n ce s ................................................................................................................... 34 PART 3 DEVELOPMENT OF A REV 8 CATALOG ............................................................ 35 3.1 Revised Assignments of Parameters for 1886 Charleston Era Earthquakes ........... 35 3.2 C atalog P rocessing .............................................................................................. . . 44 3 .3 R e fe re nce s ................................................................................................................... 45 TABLES Table 1 Earthquakes Identified as RI that are too Small to be Included in the CEUS-SSC Catalog Table 2 Earthquakes Correctly Classified in Rev 7 of the CEUS-SSC Catalog Table 3 Earthquakes Classified as RI in the References Consulted in this Review, but Considered Tectonic in Rev 7 of the CEUS-SSC Catalog Table 4 Earthquakes that should be classified as RI or Probable RI Table 5 NPPs in the Southeastern U.S.

Table 6 Questioned Charleston SC Area Earthquakes from Rev 7 of CEUS SSC Catalog Table 7 Revised Locations and Uniform Magnitudes for Specific Earthquakes near Charleston, SC FIGURES Figure 1 Location of the earthquakes listed in Table 4 (circles) with respect to NPPs in the southeastern US located in proximity of a lake or reservoir (triangles).

Earthquakes are color-coded by focal depth.

Figure 2 Seismicity within 100 km of the Oconee NPP (from Rev 7 of the CEUS-SSC earthquake catalog).

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Figure 3 (a) Close-up view of the cluster of seismicity near the Oconee NPP; (b) map showing the location of Oconee NPP (A) with respect to the lake.

Figure 4 Seismicity within 100 km of the VC Summer NPP (from Rev 7 of the CEUS-SSC earthquake catalog).

Figure 5 Close-up view of the seismicity cluster to the NW of the VC Summer NPP.

Figure 6 Comparison of the seismicity near VC Summer NPP from rev 7 of the CEUS-SSC catalog (red and green circles) with the seismicity recorded between 1996 and 1999 (black asterisks) as presented in Figure 2 of [12] (in the background).

Figure 7 (a) Seismicity within 100 km of the Catawba NPP (from Rev 7 of the CEUS-SSC earthquake catalog); (b) location of the Catawba NPP (A) with respect to Lake Wylie (the figure is shown on a different scale).

Figure 8 Seismicity within 100 km of the Robinson NPP (from Rev 7 of the CEUS-SSC earthquake catalog).

Figure 9 Seismicity within 100 km of the McGuire NPP (from Rev 7 of the CEUS-SSC earthquake catalog).

Figure 10 Seismicity within 100 km of the Harris NPP (from Rev 7 of the CEUS-SSC earthquake catalog).

Figure 11 Seismicity within 100 km of the Hatch NPP (from Rev 7 of the CEUS-SSC earthquake catalog).

Figure 12 Seismicity within 100 km of the Vogtle NPP (from Rev 7 of the CEUS-SSC earthquake catalog).

Figure 13 Seismicity within 100 km of the Lee NPP (from Rev 7 of the CEUS-SSC earthquake catalog).

Figure 14 Seismicity within 100 km of the Brunswick NPP (from Rev 7 of the CEUS-SSC earthquake catalog).

Figure 15 Seismicity within 100 km of the Surry NPP (from Rev 7 of the CEUS-SSC earthquake catalog)

Figure 16 Seismicity with E[M] >_2.9 occurred within 100 km of the Oconee NPP from 1968 through December 2007: a) from Rev 7 of the CEUS-SSC earthquake catalog; b) from Rev 8 Figure 17 Seismicity with E[M] >_2.9 occurred within 100 km of the VC Summer NPP from 1968 through December 2007: a) from Rev 7 of the CEUS-SSC earthquake catalog; b) from Rev 8 Figure 18 Isoseismal map for January 19, 1860 earthquake provided by Donald Stevenson and Dr. Predeep Talwani (written communication, February 19, 2014).

Figure 19 Comparison of ln(FA)-I 0 data for Category 3 Earthquakes from Seeber and Armbruster (1987) with data from other earthquakes from the CEUS SSC Rev 7 catalog Figure 20 Comparison of In(FA)-Io data for Category 4 Earthquakes from Seeber and Armbruster (1987) with data from other earthquakes from the CEUS SSC Rev 7 catalog Figure 21 Comparison of ln(FA)-Io data for Category 5 Earthquakes from Seeber and Armbruster (1987) with data from other earthquakes from the CEUS SSC Rev 7 catalog.

APPENDIX Appendix A Donald Stevenson to Dr. Youngs Emails Amec Foster Wheeler 2 X:188000M1s8180\3000_REPORTS TO CLIENT\CEUSSSCCatalogUpdate_042315\CEUSSSC_CatalogUpdate 04 23 2015.docx

PART 1 IDENTIFICATION OF ADDITIONAL RESERVOIR INDUCED SEISMICITY (RIS)

EARTHQUAKES IN THE SOUTHEASTERN U.S.

In developing the CEUS SSC catalog, earthquakes identified as reservoir induced (RI) were removed from the final earthquake listing. The sole source for this identification in the southeastern US was the set of available Southeast US Seismic Network (SEUSSN) Bulletins that contain 120 RI earthquakes. Sixteen of these were large enough to be included in the CEUS SSC catalog; these earthquakes occurred primarily near Monticello Reservoir and Lake Keowee. These earthquakes were removed from the final (Rev 7) CEUS SSC catalog published in NUREG-2115.

At the request of EPRI, we have performed additional reviews of publicly available sources to identify additional RI earthquakes that are in the CEUS SSC catalog. In addition to the references listed in the following section, the SEUSSN Bulletins from 1979 to 1980 were re-examined. In cases where the references consulted are not in agreement, expert judgment is used to classify an earthquake as RI on other considerations, such as the proximity to a reservoir and shallow focal depth, or the temporal relation to the reservoir filling.

1.1 REFERENCES

The following list contains the additional reference material consulted to identify potential RI earthquakes in the CEUS SSC catalog.

[1] Acree, S.D., Acree, J.R., and P. Talwani, 1988, The Lake Keowee, South Carolina earthquakes of February through July 1986, Seismological Research Letters, 59 (2),

63-70.

[2] Talwani, P., 1981, Earthquake Prediction Studies in South Carolina, in "Earthquake Prediction: An International Review". American Geophysical Union.

[3] Talwani, P., 1990, Appendix D in Krinitzsky, E.L. and J.B. Dunbar (1990): "Geological Seismological Evaluation of Earthquake Hazards at Hartwell and Clemson Upper and Lower Dams, South Carolina". Technical Report GL-90-1 1, Final Report prepared for US Army Engineer District Savannah, Savannah, Georgia.

[4] Talwani, P., 1997, On the Nature of Reservoir-induced Seismicity, Pure and Applied Geophysics, 150, 473-492.

[5] Talwani, P., Stevenson, D., Amick, D., and J. Chiang, 1979, An Earthquake Swarm at Lake Keowee, South Carolina, Bulletin of the Seismological Society of America, 69 (3),

825-841.

[6] Long, L.T., Kocaoglu, A., Hawman, R., and P.J.W. Gore, The Norris Lake earthquake swarm of June through September, 1993; Preliminary Findings. Seismological Research Letters, 65 (2), 167-171.

[7] Fletcher, J.B., Boatwright, J., and W.B. Joyner, 1983, Depth dependence of source parameters at Monticello, South Carolina, Bulletin of the Seismological Society of America, 73 (6), 1735-1751.

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[8] Chen L., and P. Talwani, 2001, Mechanism of Initial Seismicity Following Impoundment of the Monticello Reservoir, South Carolina, Bulletin of the Seismological Society of America, 91 (6), 1582-1594.

[9] Rajendran, K., and P. Talwani, 1992, The role of elastic, undrained, and drained responses in triggering earthquakes at Monticello Reservoir, South Carolina, Bulletin of the Seismological Society of America, 82 (4), 1867-1888.

[10] Shedlock, K.M., 1988, Seismicity in South Carolina, Seismological Research Letters, 59 (4),

165-171.

[11] Tarr, A.C., Talwani, P., Rhea, S., Carver, D., and D. Amick, 1981, Results of recent South Carolina seismological studies, Bulletin of the Seismological Society of America, 71 (6),

1883-1902.

[12] Chen L., and P. Talwani, 2001, Renewed seismicity near Monticello Reservoir, South Carolina, 1996-1999, Bulletin of the Seismological Society of America, 91 (1),94-101.

[13] Marion, G.E., and L.T. Long, 1980, Microearthquake spectra in the Southeastern United States, Bulletin of the Seismological Society of America, 70 (4), 1037-1054.

[14] Reinbold, D.J., and Johnston, A.C., 1987, Historical Seismicity in the Southern Appalachian Seismic Zone: U.S. Geological Survey Open-File Report 87-433.

[15] Stover, C.W., and Coffman, J.L., 1993, Seismicity of the United States, 1568-1989 (Revised): U.S. Geological Survey Professional Paper 1527, 418 pp.

1.2 REVIEW RESULTS The documents listed above were reviewed to identify events in the CEUS SSC catalog that should be classified as RI events. It should be noted, though, that these references often list the earthquakes vaguely by month and year, without a precise date or magnitude. Epicentral coordinates are usually not listed. As an example: [4], [9], [10], [12] do not identify any individual earthquake. In addition, most of the RIS is low magnitude (less than 2), which was typically not included in the CEUS-SSC catalog.

The following Tables 1, 2 and 3 show all the RI earthquakes that are reported with a date and occasionally magnitude in the references above. In particular, Table 1 contains earthquakes identified as RI that were too small to be included in the CEUS SSC Rev 7 catalog; Table 2 lists three earthquakes that we consider to have been correctly classified in the Rev 7 CEUS SSC catalog; and Table 3 contains additional earthquakes described in the above references that are not classified as RI earthquakes in the CEUS SSC Rev 7 catalog.

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TABLE I EARTHQUAKES IDENTIFIED AS RI THAT ARE TOO SMALL TO BE INCLUDED IN THE CEUS-SSC CATALOG Earthquake Reference 1978/10/27 [7]

1979/1/19 [1]

1976/1/14 [2]

1977/2/23 [2]

1987/12/24 [3]

1988/1/26 [3]

1993/9/23 [6]

Events 1 through 40 and 42 through 53 in Table 1 [8]

All events listed in Table 1 L[13 TABLE 2 EARTHQUAKES CORRECTLY CLASSIFIED IN REV 7 OF THE CEUS-SSC CATALOG ID Date Magnitude Comment TMP10113 1979/10/16 M 3.0 Ref. [7] analyzed four well-recorded reservoir induced earthquakes near the Monticello reservoir to determine stress drop. The events are taken from Fletcher (1982). This earthquake was identified as RI in the Rev 7 CEUS-SSC catalog.

TMP14740 1986/2/16 E[M] 3.32 Ref [1] states there is no correlation between reservoir level and the onset of seismicity (this event), while rapid fluctuations in the water levels were observed before the subsequent events in June (see below) and July. The SEUSSN Bulletins do not classify this as RI, therefore the earthquake was included in the Rev 7 CEUS-SSC catalog as a tectonic earthquake.

We note that Dr. Martin Chapman considers this to be RI earthquake due to its location at the shoreline of Lake Keowee.

TMP14964 1986/6/11 Md 2.8 This event was identified as RI in the Rev 7 CEUS-SSC catalog from the SEUSSN Bulletins.

Amec Foster Wheeler

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TABLE 3 EARTHQUAKES CLASSIFIED AS RI IN THE REFERENCES CONSULTED IN THIS REVIEW, BUT CONSIDERED TECTONIC IN REV 7 OF THE CEUS-SSC CATALOG ID Date Magnitude Comment TMP07012 1969/12/13 E[M] 3.46 Ref. [5] argues that location of this event is based on "meager macroseismic data" and the earthquake could be a RI event at Lake Keowee.

This earthquake is too old to be listed in the SEUSSN Bulletins therefore it was not classified as RI in Rev 7 of the CEUS-SSC Catalog.

Because the event is poorly located and Ref. [5]

does not conclusively classify it as RI, our recommendation is that it should remain in the catalog as a tectonic earthquake.

TMP07159 1971/7/13 E[M] 3.63 Ref. [5] suggests that the location of the Seneca earthquake by Bollinger (1972) is less accurate than the location by Sowers and Fogle (1978),

which is based on detailed macroseismic studies.

The Sowers and Fogle (1978) location coincides with observed RIS.

This earthquake was considered a tectonic event in Rev 7 of the CEUS SSC catalog because: 1) it is too old to be listed in the SEUSSN Bulletins, and 2) it appears (as a tectonic event) in a number of catalogs: EPRI, NCEER91, USGS, SEUSSN, South Carolina seismic network, Reagor, Stover and Coffman, and Hopper.

Our conclusion is that the more precise location by Sowers and Fogle (1978) suggests that it may be a RI earthquake and the recommendation is to identify it as a probable RI (non-tectonic) earthquake.

TMP07565 1974/8/2 E[M] 3.91 The earthquake is mentioned in Ref. [111 with references to existing literature (by Dr.Talwani) suggesting that the earthquake is RI, caused by variation in pore-pressure caused by fluctuations of the water level in the reservoir. More recently, Ref.

[3] says that despite the excellent correlation between water fluctuations and earthquakes, "The observation that the seismicity occurred 43 km upstream of the Clarks Hill dam and 22 years after its impoundment led to the questioning of the suggestion that the activity was induced".

The earthquake is too old to appear in the SEUSSN Bulletin therefore it was not classified as RI in Rev 7 of the CEUS-SSC Catalog.

Based on Ref [3] the categorization of this Amec Foster Wheeler 6 X:\18000s\18O180\3000_REPORTS TO CLI ENTRCEUS_SSC_Catalog_Update_042315\CEUSSSCCatalogUpdate 04 23 2015.docx

TABLE 3 EARTHQUAKES CLASSIFIED AS RI IN THE REFERENCES CONSULTED IN THIS REVIEW, BUT CONSIDERED TECTONIC IN REV 7 OF THE CEUS-SSC CATALOG ID Date Magnitude Comment earthquake as RI is questionable and our recommendation is to retain the event in the CEUS SSC catalog as a tectonic earthquake.

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TABLE 3 EARTHQUAKES CLASSIFIED AS RI IN THE REFERENCES CONSULTED IN THIS REVIEW, BUT CONSIDERED TECTONIC IN REV 7 OF THE CEUS-SSC CATALOG ID Date Magnitude Comment TMP08078 1975/11/25 E[M] 3.21 Ref. [11] references this earthquake among those correlated to reservoir activity and indicates that following this event a monitoring program was carried out in the vicinity of Lakes Jocassee and Keowee.

This earthquake is too old to appear in the SEUSSN Bulletin therefore it was not classified as RI in Rev 7 of the CEUS-SSC Catalog. Our recommendation is to identify the event as a RI earthquake.

TMP08787 1977/9/7 E[M] 2.77 Ref. [2] says this event was found to be associated with changes in water levels at a 100 m deep observation well. The water level was smoothed and corrected for recharge from Lake Keowee and barometric pressure, and the effect of earth tides, ocean tides and winds was found to be negligible.

Ref. [2] finds that the water level changes (in the order of 9 cm) are correlated with magnitude and hypocentral distance.

This earthquake does not appear in the SEUSSN Bulletin. Recommendation is to identify the event as a RI earthquake, although it is smaller than earthquakes used in recurrence calculations.

TMP08971 1978/1/25 E[M] 2.6 This earthquake is #41 in Table 1 of [8], which lists events recorded during the impounding of the Monticello Reservoir by the local monitoring seismic network.

SEUSSN Bulletin reports the earthquake as 25 January 1978 Jenkinsville, South Carolina, ML 2.8 (USC), Lat 34.3 N, Long 81.3W at 3:29:38.7 and depth of 2 km. A note in parenthesis reads: "Same event as the 8/29/38.9 shock in the microearthquakes in South Carolina listing?".

Because the SEUSSN Bulletin does not classify this event as RI, the earthquake was retained to be tectonic in Rev 7 of the CEUS SSC catalog.

Recommendation is to identify the event as a RI earthquake, although it is smaller than earthquakes used in recurrence calculations.

TMP09000 1978/2/11 E[M] 2.93 This earthquake is not classified as RI in the SEUSSN Bulletins, but its location and shallow depth suggests in may be RIS. Recommendation is to identify the event as a probable RI earthquake.

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TABLE 3 EARTHQUAKES CLASSIFIED AS RI IN THE REFERENCES CONSULTED IN THIS REVIEW, BUT CONSIDERED TECTONIC IN REV 7 OF THE CEUS-SSC CATALOG ID Date Magnitude Comment TMP09354 1978/8/27 E[M] 2.93 This earthquake is not listed in the SEUSSN Bulletin. This earthquake is one of the four events studied in [7]: its location is obtained from Fletcher (1982). Recommendation is to identify the event as a RI earthquake.

TMP09355 1978/8/27 E[M] 2.77 This earthquake is not listed in the SEUSSN Bulletin. This earthquake occurred immediately after TMP09354 in nearly the same location and was flagged as a dependent event. It has an assigned depth of 7 km, which is much deeper than typical RIS. Recommendation is to identify the event as a probable RI earthquake, although it is smaller than earthquakes used in recurrence calculations.

TMP09460 1978/10/27 E[M] 3.08 This earthquake is not listed in the SEUSSN Bulletin. This earthquake is one of the four events studied in [7]. Location is obtained from Fletcher (1982). Recommendation is to identify the event as a RI earthquake.

TMP10034 1979/8/26 E[M] 3.64 This earthquake is listed in Ref. [2] among the earthquakes associated with the Monticello Reservoir, and was also identified in the SEUSSN Bulletin as RI. Recommendation is to identify the event as a RI earthquake.

TMP10104 1979/10/8 E[M] 3.16 Reexamination of the SEUSSN Bulletin indicates that this event is listed as associated with a reservoir. Recommendation is to identify the event as a RI earthquake.

TMP10109 1979/10/14 E[M] 3.08 Reexamination of the SEUSSN Bulletin indicates that this event is listed as associated with a reservoir. Recommendation is to identify the event as a RI earthquake.

TMP10506 1980/7/29 E[M] 3.31 This earthquake was not flagged in the SEUSSN Bulletin as associated with a reservoir and its location quality was listed as D. However, its location and shallow depth makes it a candidate as a RI earthquake. Recommendation is to identify the event as a probable RI earthquake.

TMP16282 1988/1/27 E[M] 2.32 Ref. [3] says activity is typical of reservoir induced sequences. SEUSSN Bulletin lists this event as "possible earthquake". Recommendation is to identify the event as a RI earthquake, although it is smaller than earthquakes used in recurrence calculations.

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Table 4 contains a summary list of 15 earthquakes that, based on our review of references [1]

through [13], should be classified as RI or probable RI and therefore not included in the CEUS SSC earthquake catalog used for recurrence parameter calculations. Once these events were identified, the Version 7 CEUS SSC earthquake catalog was examined for events with similar characteristics (namely: location, shallow depth, and temporal correlation). This analysis identified 18 additional earthquakes that should be classified as RI or probable RI earthquakes, also listed in Table 4.

TABLE 4 EARTHQUAKES THAT SHOULD BE CLASSIFIED AS RI OR PROBABLE RI.

TMPID yr mo Dy hr mn sec Lat Ion depth E[M] Comment TMP07159 1971 7 13 11 42 26 34.8 -83 n/a 363 Probable RI TMP08078 1975 11 25 15 17 34.8 34.93 -82.9 10* 3.21 RI TP....................

TMP08787 8 7 .......... 197........

1977 .....9 ......7................ 14 . . . 41 . . . . ....

2. -* 1.*

32.7 -34.982 .2 T. .... -*-

-82.927 *: .....

....... n/a........ ...... 2.....

2.77 6...................... ......................

RI ,

TMP08971 1978 1 25 8 29 39 34.301 -81.234 5* 2.6 RI TMP09354 1978 8 27 10 23 8 34.313 -81.337 2 2.93 RI TMP08998 1978 2 10 20

............. ................... . I.... ............ ....... ..... ....... .... .... ... ............ ................

23 38.7 34.343 -81.348 1 2.77 Probable RI

...... ........... " ....... .. .. ... ...... ............... ....................... ..I ..... .. . ...

..TMP08999 TP 9 0 1978

............................................ 7 .. 2 ... 11 05 .............

1...... ............. 19 19 . 0.7 0..2 ....... 34.343 3-9 ........

4 .. .....-......

.3 -81.35 1..............

3 9 1.... 312

...........-----------.... ..2.77

..9I.... ...........Probable b le RI P r.................................

R TMP09000 1978 ....... 2........ ......11. .... .............

... ........................... , ................ 5 ................

19 ........0.2 ......... .- . 34.346 -81.349

.......... . .. ... ............... 1

............ ...................... . .....2.93 Probable RI TMP09006 . ............

............................... 1978 . ......... .. 2 . . ...14. ... ............

12 45

............ ...7.2 - 34.342

. ......--- - - --- -81.346 . ......... ..2. .....

. 2.77

........ Probable

......... RI TMP09007 1978 2 14 13 9 59.5 34.351 -81.343 2 2.85 Probable RI

............................. . .......................... .... ......... .... ... ..... ............. ................ .......... ....... * ......... .... .......... ............. .............. .......... .............. ....... ....... ....4 ............... ...........................

TMP09013 1978 2 15 21 14 34.2 34.349 -81.346 0 2.77 Probable RI TMP09014 1978 2 16 2 14 33.4 34.332 -81.362 2 2.85 Probable RI

...................................... .......... ......... .... ....... .......................... ................. ................ ..... .37.. ... .... -8 .............. 35 1----.....2-...... 8.. Pr ba leR..................................

TMP09023 1978 2 22 7 13 25.1 34.327 -81.35 1 2.85 Probable RI

.. ........ 4---

1 . .R Probable RI TMP09024

................ ..................... 1978

.......... . ..........2....... ......22 12 ................

....... .............. 13 ..... 24.3

.. .... 34.339

......... ...... ............ -81.352

" .. 3.................. ............ .3.00

.. 7...

7 ... P..................

r ba.

TP 9 2. .. . ......... 7 ....... 2-2 . ..... . ............

1 3 ....... ...... ..... .

...... -9... ------ - -------------. . ..... .... .. . P r . b . b.~ .............

TMP09027

.. .......... ................... 1978

.................... .. 2

.. . 24

......... 7 34 10.5

.... . ...... ............ ...... ... ..... .......... . 34.334

..... -81.348 I-------........... 1........... 2.93 . .

..... . ... Probable RI TMP09029 1978 2 25 4 2 42.7 34.345 -81.351 1 2.77 Probable RI TMP09031 P.. 9....... .... ..........1978............. 2 ...26....... .....6 .................52 .... 35.4 .....................

34.315 -81.297 ... . . . . . . . . . . . . .1. ...2.85 Probable RI TMP09032 1978 2 26 11 52 33 34.391 -81.361 1 3.00 Probable RI

.. ... ..................... .... ........... ......... ...... . . .. .- 1.. ....... .... ........ ................. ....... ..........

TMP09033

.. TP ................. 4 .......... 1978 9.......... ............ ....... 2. ............. 26 .......... 18 ................217.....................

10 48.8 * " F 34.321 4 .-1

.... ....... " "-81.348 8 i13i.................. 0 3.08

-2.......................... Probable r b b e RI 2 8 .................................................. R TMP09343 1978 8 24 10 23 7.6 34.311 -81 .341 2 2.85 Probable RI TMP09355 1978 8 27 10 23 8 34.313 -81.337 7 2.77 Probable RI TMP09460 1978 10 27 16 27 18.1 34.302 -81.326 2 3.08 RI TMP09518 1978 11 24 111 54 40.9 34.296 1-81.347 1 1 2.85 Probable RI Amnec Foster Wheeler 10 0X:\18000s\180180\3000_REPORTS TO CLIENT\CEUSSSCCatalogUpdate_042315\CEUSSSC CatalogUpdate 04_23 2015.docx

TABLE 4 EARTHQUAKES THAT SHOULD BE CLASSIFIED AS RI OR PROBABLE RI.

TMPID yr mo Dy hr mn sec Lat Ion depth E[M] Comment TMP10034 1979 8 26 1 31 45 34.916 -82.956 1 3.64 RI

. ... . . .. . .... ....... .... I . ............. ......... ............... ..................

................. ..... . -.......... ........ . I..................

TMP39374 1979 10 8 8 54 19.4 34.31 -81.33 2 2.85 RI TMP10104 1979 10 8 23 20 11 34.306 -81.344 1 3.16 RI TMP10109 1979 10 14 8 24 57.6 34.306 -81.338 2 3.08 RI TMP10506 1980 7 29 1 10 22.7 34.351 -81.364 1 3.31 Probable RI TMP16282 1988 1 27 22 5 42.9 34.189 -82.75 6.1 2.32 RI

depth 17 km in Reinbold and Johnson [14]

- depth 1 km in Stover and Coffman [15]

Figure 1 shows the location of the earthquakes listed in Table 4 with respect to the NPPs that are located next to a lake or reservoir. The RI earthquakes are located near the Oconee and VC Summer NPP and their reservoirs (Monticello, Lake Keowee, Lake Jocassee) that are known areas of RIS.

In order to verify that there are no clusters of seismicity of non-tectonic origin in proximity of other NPPs in the Southeastern U.S., we analyzed the seismicity within 100 km of all the NPPs.

The analyses are described in the following section.

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3XN __ -____

Focal depth 405' --

0 unknown 00<2 km ---............... -------------- ---------------------------...........................-- ......................

--..........................1<2km o 2 -5 km Harris 0 >5 km A McGuire A ,Catawba ...........

AikOconee Robinson A

20'................-----

VC Summer 3401 .0 ----------- Jt*,. #

w 83 w 820 W slow 800W C7-WV Figure 1: Location of the earthquakes listed in Table 4 (circles) with respect to NPPs in the southeastern US located in proximity of a lake or reservoir (triangles). Earthquakes are color-coded by focal depth.

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1.3 SEISMICITY WITHIN 100 KM OF NPPs IN THE SOUTHEASTERN U.S.

The seismicity in the vicinity of NPPs in the southeast US that are near reservoirs was examined to look for potential clusters of earthquakes of non-tectonic origin. Table 5 lists the NPPs in the Southeastern U.S., highlighted in bold are the six plants located near a lake or reservoir, namely Oconee, Summer, Catawba, Robinson, McGuire and Harris.

TABLE 5 NPPS IN THE SOUTHEASTERN U.S.

No. Nuclear site Latitude (deg) Longitude (deg) State Nearby Lake/River 1 Hatch 31.9342 -82.3444 GA Altamaha River 2 Vogtle 33.1419 -81.7647 GA Savannah River 3 Oconee 34.7917 -82.8986 SC Lake Keowee 4 Lee Nuclear 35.0369 -81.5118 SC Broad River 5 Summer 34.2958 -81.3203 SC Monticello Reservoir 6 Catawba 35.0514 -81.0694 SC Lake Wylie 7 Robinson 34.4053 -80.1586 SC Lake Robinson 8 McGuire 35.4322 -80.9483 NC Lake Norman 9 Harris 35.6333 -78.9561 NC Shearon-Harris Reservoir 10 Brunswick 33.9583 -78.0106 NC Coastal (Cape Fear River) 11 Surry 37.1656 -76.6983 VA James River The seismicity within 100 km of the six NPPs was extracted from the CEUS SSC earthquake catalog (rev 7) and plotted to see ifthere are any clusters of earthquakes showing a spatial correlation with the reservoirs. These data are shown in Figures 2 through 15. The purpose was to assess whether or not the seismicity pattern post-impoundment of the reservoirs is consistent with the distribution of earthquakes pre-impoundment. In addition, the depth of the earthquakes pre- and post-impoundment is used as an indicator of RIS.

In all figures:

- filled circles are earthquakes that occurred after the lake impoundment that are identified as mainshocks;

- filled squares are earthquakes that occurred prior to the lake impoundment that are identified as mainshocks;

- open circles and open squares are dependent events (post-and pre-impoundment respectively);

- unknown depths are plotted in blue;

- depths less than 2 km are plotted in red;

- depths between 2 and 5 km are in green;

- depths greater than 5 km are in black;

- the NPP site is shown by a yellow triangle.

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1.3.1 NPPs Located on Lakes and Reservoirs Oconee There are 155 earthquakes within 100 km of the Oconee NPP. Most of the seismicity pre-1973 has unknown depth (fixed at 0). In Ref [5] the depth of the swarm is limited to the topmost 2 km.

Oconee k1.9~21N-- -

pre-impoundment m unknown

<2km

2-5km N >5km post-impoundment 350N -- -- ----- -

unknown

---WW * " <2km

% " 2-5km NY 1ý 1W -tl---~IiiiT- - - - - - - " >5km 34ON I I3 NY.

.221.LI I 84gOW 301 83OW 82OW W NO Figure 2: Seismicity within 100 km of the Oconee NPP (from Rev 7 of the CEUS-SSC earthquake catalog).

The next figure shows a zoom of the seismicity cluster near the NPP (Figure 3a). These earthquakes are likely RI events from Lake Keowee (compare Figure 3a with 3b): they are typically shallow and occurred after the impoundment of the lake, in areas that have no prior seismicity.

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Oconee - zoom 2q '0U 10, 35ON SVI 12' V 830W 54 4 (a)

(b)

Figure 3: (a) Close-up view of the cluster of seismicity near the Oconee NPP; (b) map showing the location of Oconee NPP (A) with respect to the lake.

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VC Summer There are 262 earthquakes within 100 km of the VC Summer NPP (Figure 4). The seismicity pre-1978 (time of the lake impoundment) has unknown depth (fixed at 0). The figure shows a cluster of seismicity very near the NPP, which is associated with the Monticello Reservoir.

Summer WI pre-impoundment m unknown

<2km 35PN " 2-5km

" >5km post-impoundment

unknown

<2 km

2-Skm

> km

0.

~~- -~~.E-E J-- - ------

I 30 4.U I

- 30w 3V 820'W ' 81%V 3 NoW 0

Figure 4: Seismicity within 100 km of the VC Summer NPP (from Rev 7 of the CEUS-SSC earthquake catalog).

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Summer - zoom

U:

pre-impoundment I

m unknown

N <2 km t

0 2-6km 24 - - - - - - - - ------------------------------- ---------- ------------------ 2 >5km 0 ' aost-impoundmenl

, unknown

.0 0 <2km 02-6km 0>

9 6km 18,------------------------------------------------- i-----------------

12-------------------- ------------------ ------------------ -------------------

%-.- M Ik 12 24' 18' 6 811W Figure 5: Close-up view of the seismicity cluster to the NW of the VC Summer NPP.

Figure 5 is a close-up view of the seismicity nearby the power plant. The earthquakes closer to the NPP have consistently depths of less than 2 km. The figure also shows that many of the earthquakes are removed in the declustering process (open circles indicate dependent earthquakes). Figure 6 compares the seismicity near the VC Summer NPP to Figure 2 of [12] (in the background) that shows the seismicity from 15 December 1996 to 31 December 1999 in the same region. Also shown in Figure 2 of [12] are two deep wells (W1 and W2) and the seismic Amec Foster Wheeler X\18000s\1 8018 Cc3000_REPORTS TO CLIENT\CEUSSSCCatalogUpdate_042315\CEUSSSCCatalog_Update 04 23 2015.docx 17

stations MR01, MR05, MR07, MR10 and JSC that have recorded the 1996-1999 earthquakes (black asterisks).

81020' 810168 340201 340j 6 Figure 6: Comparison of the seismicity near VC Summer NPP from rev 7 of the CEUS-SSC catalog (red and green circles) with the seismicity recorded between 1996 and 1999 (black asterisks) as presented in Figure 2 of [12] (in the background). Earthquakes with unknown depth from Figure 5 are not shown.

The northernmost cluster is probably in the area of the deep well W1; the three earthquakes that are lined up closer to the site have occurred in 1978, 1979 and 1982. The earthquakes shown in Figures 5 and 6 include the earthquakes identified in Table 4 as RI or potential RI (and therefore removed from Version 8 of the CEUS SSC catalog). The remaining earthquakes, if not removed by declustering, have magnitudes E[M]<2.9, which is the minimum magnitude used in recurrence analysis, therefore have no impact on the seismic hazard calculations.

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Catawba There are 136 earthquakes within 100 km of the Catawba NPP (Figure 7a). The seismicity pre-1975 has unknown focal depth. If these earthquakes are removed, the nearest earthquake has a depth of 23 km. The NPP is located on Lake Wylie (see Figure 7b from google maps): the earthquakes closer to the lake occurred prior to its impoundment. The cluster of earthquakes to the south is about 100 km of distance from the NPP. A search of literature (BSSA and SRL) did not return any specific study of the seismicity of Lake Wylie. Note that the cluster of seismicity located approximately 100 km south-southwest of Catawba is associated with the Monticello reservoir and is discussed previously.

Catawba 0

3&

pre-lmpoundment m unknown

" <2km 40

- - -- -- -- - - -- -- - -- -- -- - " 2-Skm E >6km 20

3ost-lmpoundment

unknown

<2 km 0 2-Skm 35'-N * @0 * >6km J, ---

2O

-- -- -- -- A !-- - ---- . .. ...

,aoka N

'W 82OW 30 81 0w W# 80 0 1W (a)

(b)

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Figure 7: (a) Seismicity within 100 km of the Catawba NPP (from Rev 7 of the CEUS-SSC earthquake catalog); (b) location of the Catawba NPP (A) with respect to Lake Wylie. The map is shown at a smaller scale than part (a)..

Robinson There are 134 earthquakes within 100 km of the Robinson NPP (Figure 8), of which 17 (all post 1975) have an estimate of the focal depth. The nearest earthquake to the NPP has unknown depth. Figure 8 does not show clusters of seismicity associated with Lake Robinson. The two independent events closest to the NPP are the 1959 Chesterfield County earthquake and an earlier event in 1930 located about 5 km to the west of the 1959 event. The two earthquakes are located based on macroseismic intensities and felt area only, and SEUSSN gives to both earthquakes a location error of 83.4 km. We found no information in the literature on the 1959 earthquake that associates the event to the impoundment of Lake Robinson.

Robinson pre-impoundment 20------------------------------------ ---------... unknown E <2km

*2-5km 35' N ......... n -----------

T, - >5 km a ,post-impoundment 11I

unknown 40' - .---------

-- - A.. -, -----------.......... 0 < 2 km

= *, *2-5km

: , _A * >5km 20' ---------.... 6 : ----------- ----------

b 34°N ------- ,- t_% -

0 "i ME 40' ...----.------------- ,.----------- , ------------ -------

820 W Blow 39 80 0 W 79OW Figure 8: Seismicity within 100 km of the Robinson NPP (from Rev 7 of the CEUS-SSC earthquake catalog).

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McGuire There are 46 earthquakes within 100 km of the McGuire NPP (Figure 9), of which 19 have an estimated focal depth (all post-1970). The seismicity doesn't show clusters in the area of Lake Norman.

McGuire pre-1950 post-1950 pre-impoundment 20' * <2 k m * <2 km ----------------- - . . . . . .. m unknown

2-6 km .2-5 km " <2ikm

>5km >5 km * " 2-5km 36'N * >5km i I post-impoundment

unknown 40' -----------

<2km

2-5km

- -* - - * .... m-- * > 5 km 20 i i u

, e, ,

i l 4 35PN

--------------- ----- J--------------U 40' NY 82OW W0 810W 30 80OW Figure 9: Seismicity within 100 km of the McGuire NPP (from Rev 7 of the CEUS-SSC earthquake catalog).

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Harris There are 16 earthquakes within 100 km of the Harris NPP (Figure 10) of which only 2 have been instrumentally recorded: one in 1981 with a depth of 1km and one in 1993 with a depth of 5 km. Both are far from the Shearon-Harris Reservoir.

Haris 37ON F I r pre-impoundment 40'

unknown i * [ <2km 2&

2-5km

~ I------- ------ * >5km 36PN post-impoundment

- -- - - - -- - - - - -L - - - - - - - - -

--

unknown 40Y I I * <2km 2&~

2-6km

> 5 km U d W 79W - 78OW 77TN 76OW 75fW Figure 10: Seismicity within 100 km of the Harris NPP (from Rev 7 of the CEUS-SSC earthquake catalog).

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1.3.2 NPPs Located on Rivers Hatch There are 5 earthquakes within 100 km of the Hatch NPP (Figure 11). Note that the figure only shows four earthquakes because two are superimposed.

Hatch 81%w Figure 11: Seismicity within 100 km of the Hatch NPP (from Rev 7 of the CEUS-SSC earthquake catalog).

Amec Foster Wheeler

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Vogtle There are 94 earthquakes within 100 km of the Vogtle NPP (Figure 12). The spatial distribution of locations of pre- and post-1950 earthquakes are similar, and the depths are consistent.

VogUe pre-1970 20'

, unknown N <2kmn I i N2-5kin 340 N 0 0

. Upost-1 970

,*0 E *unknown 40a

"'0 ---- --

o6kr ...

. 2 m 0 <2km 2-

<~ k p .v* :0 ,>6km 20' 33ON ---- .----....- --------

0 -----------

i i i*:

a i i t L..i :l-----

I , I 40' * , U W~Zz230' I

83') 82OW 39 81 0 w 30' 800W Figure 12: Seismicity within 100 km of the Vogtle NPP (from Rev 7 of the CEUS-SSC earthquake catalog).

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Lee There are 164 earthquakes within 100 km of the Lee NPP (Figure 13). Most of the seismicity pre-1978 has unknown depth (fixed at 0).

Lee 36PN 800W Figure 13: Seismicity within 100 km of the Lee NPP (from Rev 7 of the CEUS-SSC earthquak e catalog).

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Brunswick There are 45 earthquakes within 100 km of the Brunswick NPP (Figure 14); none of them has an estimate of the focal depth. The NPP is located near the coast.

Brunswick Figure 14: Seismicity within 100 km of the Brunswick NPP (from Rev 7 of the CEUS-SSC earthquake catalog).

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Surry There are 31 earthquakes within 100 km of the Surry NPP (Figure 15) of which 8 (post-1978) have an estimate of focal depth. The plant is located on the James River.

Surry 38'N ; ;

i I 40 ---- -- -- - --- -- I- - -- - - - - - - -

i i

2 N37>N U >5km, , >5km 20- ------------ ------------------ +/------

7 W4' 40' 9.......to 20

-- i

' ....... in 40' a 20! o calculations.

The earhquake in Tal idetfe 4 eermvdfo h aalgadanwRv8oh Fiue1 hw ta o h rbbeR Thryadtoa evnt.i.Tbl artqake 4--are.located.in.proximity..

wer idetfe

conee-and;VC of.two.NP. s:

inteRv7CU- aao Summer.

earthqakes Te locaed withi 10 'moahNP eepotd n nlzdt idetiy nyoterlute o sismciy fontectni oriin Figre16copaesth earhqaks wthEfMI3 29 ha occurred. fro 198t-eebr20. oae ihn10k ofth OonePP fomRe 7ofth CUS55 Caaog(igr 16)adfo\e Fgr AmcFotrWhee Figure 15 seiwsmicity wthevnsin100 kml ofrte locrre inP(froxmitey of the CEUs-SOcneadV eammrthquae eartalog). atdwti 10k fechNPwr potdad nlzdt (Tabentf 4). ofthesec21swere rfeimovedty C uwr reurec dfno-ecluterinrgin th calcaio Fatlguhie oftheparemann 9tonl 4earehqlargesenouh (E[M] 2.9) tohave beurennldd 198teartquaer ino recurrncaed calculations.

oftheeartquaes identifioed in Tablhe4 were remoedafom thgueatalo andafnew Rev 8oFigthe 80180\3000 REPORTS X:~180OOs~1 80180c3000 TO 27 X:\18000s\1 REPORTS TO 27 CLIENT\CEUSSSC_Catalog_Update_042315\CEUS SSC Catalog_Update 04 23 2015.docx

16b). The comparison indicates that the analysis presented in this report has removed several earthquakes that had previously been used to calculate recurrence rates for PSHA.

.1W-N ! 3frN i ý 30 30'

.:. ... L - '.-

35PN

,A LA! -------- --------

30N 30'

.. . .. . .. . . . . . ..-. S*. . . . . . . . . . . . . . . .

34°N I 34ON C C I = a a=

84' X. &W W 82OW 3(T 3ao -

81%w 83%V 39 82OW 3V~

(a) (b)

Figure 16: Seismicity with E[M] > 2.9 occurred within 100 km of the Oconee NPP from 1968 through December 2007: a) from Rev 7 of the CEUS-SSC earthquake catalog; b) from Rev 8.

Figure 17 shows a similar comparison for the seismicity within 100 km of the VC Summer NPP:

Figure 17a shows the earthquakes in Rev 7 of the catalog with E[M] > 2.9 occurred from 1968 to December 2007; Figure 17b shows the earthquakes from Rev 8 of the catalog. The cluster of earthquakes associated with the Monticello Reservoir has been effectively removed from the earthquake catalog in Rev 8.

Amec Foster Wheeler 28 CLIENTRCEUSSSCCatalog_Update_042315\CEUS X:18000s\180180\3000 _REPORTS TO SSC Catalog_Update 04 23_2015.docx

JbNh 4Va 0

2OC~ .

0 34 ON r -- - - - - , -- - - - - .----

-L I -

- -r-- - - -I- - - - - - - -

MIr - -- --- - - - - - - - - - - - - -- - - - - -- - - - - , - - - - -

8P0 W Wc 82OW 3: 8113W 3V 80 (a) 35PN E~I 4crY 2(Y ------------- ----------

34ON 40Y --- ----- - L.... - - - ...---------------

a-830 w S w2ow 39 Blw 3cr 60%W (b)

Figure 17: Seismicity with E[M] > 2.9 occurred within 100 km of the VC Summer NPP from 1968 through December 2007: a) from Rev 7 of the CEUS-SSC earthquake catalog; b) from Rev 8.

The analysis shown above for Oconee and VC Summer NPPs was then extended to the other NPPs located in the southeastern U.S. nearby reservoirs or other bodies of water. No other clusters of seismicity of non-tectonic origin were identified by examination of the spatial correlation of the earthquakes or temporal correlation with the reservoir impoundment (if any).

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Following the re-calculation of the seismicity rates in the Southeastern U.S. after removal of the RIS discussed above and the aftershocks of the Charleston earthquake discussed in the following, Dr. Martin Chapman has identified an additional six earthquakes that are considered by Virginia Tech to be RI. Of these, only one is large enough (E[M] 3.16) to have been included in the revised earthquake recurrence calculations. The event is located at 34.892 degrees N, 82.892 degrees W, near the Oconee NPP in the area of Lake Keowee. The event is listed in the SEUSSN Bulletins, however it is not explicitly identified as reservoir induced. Although it is agreed that the earthquake should be listed as RI in future releases of the earthquake catalog, it is expected that the impact on the earthquake recurrence analysis of removing one additional earthquake would be minor and does not warrant another update of the earthquake recurrence rates.

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PART 2 EARTHQUAKES IN SOUTH CAROLINA NEAR THE TIME OF THE 1886 CHARLESTON, SC, EARTHQUAKE SEQUENCE The table below lists 7 earthquakes from the Rev 7 CEUS SSC catalog from the time period 1799 to 1868 in South Carolina that were identified as being potentially mislocated to areas away from Charleston.

TABLE 6 QUESTIONED CHARLESTON SC AREA EARTHQUAKES FROM REV 7 OF CEUS SSC CATALOG TMPID I yr IMo IDy hr ImnI sec Lat [ Ion E[M] Source of Catalog I Location USGSnd_000145 Revised by Jeff Munsey of TvAsed on Bakun an TMP00331 1799 4 11 8 20 0 33.95 -80.18 ~TVA4.68 based on Bakun and

....... .. ... ... - -...... . ............... _o_ .. .....-Ho pper Met-h_

.. ...... d TMP01089 1860 1 19 23 0 0 33.68 -80.57 4.21 USGSnd_000427 TMP01731 18861 9 1 6 0 0 33.91 -82.02 4.54 SeebArm87_000014 TMP01739 1886] 9 1 9 45 0 34.3

-82.86 4.17 USGSnd_000771 -------

TMP02019 18861 10 22 5 0 0 34.71 -81.66 4.13 USGSnd_000805 TMP02025 TMP02360

~1 18861 10 1

22 12 14 9

45 55 0

0 33.87 34.18

-81.01

-80.17 4.5 4.33 USGSnd_000807 USGSnd_000860 The majority of these earthquakes have locations and times that come from the USGS's earthquake catalog used for seismic hazard mapping. The primary source of the USGS catalog is the NCEER-91 catalog. The events in question have alternative locations in the SUSN catalog that place them at the location of the 1886 Charleston, SC main shock. We have reviewed the identification of these earthquakes and assignment of these locations in the development of the Rev 7 CEUS SSC catalog in light of additional information in the paper by W.H. Bakun and M.G. Hopper (2004, "Magnitudes and Locations of the 1811-1812 New Madrid, Missouri, and the 1886 Charleston, South Carolina, Earthquakes," Bulletin of the Seismological Society of America, 94, 64-75) and recent information provided by Donald Stevenson and Dr.

Predeep Talwani (written communication, February 19, 2014). The individual earthquakes are discussed below.

TMP00331. 1799/4/11, E[M] 4.68.

This earthquake was originally located at the 1886 main shock site in the source catalogs.

However, additional analysis of the reported intensity data by Jeff Munesy of TVA (written communication, 2010), which includes intensity VI at Statesburg, SC and intensity V at Wilmington, NC indicates a location north of Charleston. The location in the Rev 7 catalog was obtained by Jeff Munsey using the Bakun and Hopper method. There does not appear to be a Amec Foster Wheeler X\I18000s\1 80180c3000_REPORTS TO 31 CLIENTRCEUSSSC Catalog_Update_042315\CEUS SSC Catalog_Update_04 23_2015.docx

compelling reason to move this earthquake to Charleston and the recommendation is to use the location obtained by Jeff Munsey.

TMP01 089, 1860/1/19, E[M1 4.21.

The location in the Rev 7 catalog is based on NCEER-91. Donald Stevenson and Dr. Predeep Talwani provided the isoseismal map shown below based on their interpretation of the available intensity data. This interpretation suggests a location near Charleston. The recommendation is to utilize the Charleston location given in the SUSN catalog.

Figure 18: Isoseismal map for January 19, 1860 earthquake provided by Donald Stevenson and Dr. Predeep Talwani (written communication, February 19, 2014).

TMP01731. 1886/9/1. ElMI 4.54.

As indicated by Donald Stevenson and Dr. Predeep Talwani (written communication, February 19, 2014), TMP01731 appears to be a duplicate of TMP01732, which has a Charleston location based on their evaluation of archival data. The recommendation is to remove this earthquake from the catalog as a separate earthquake.

TMP01739, 1886/9/1, E[MI 4.17.

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Donald Stevenson and Dr. Predeep Talwani (written communication, February 19, 2014) recommend that the location given in the SUSN catalog be used and the time changed to 14:45 UTC. The recommendation is based on examination of the two closest newspapers to the reported location (Abbeville Press and Banner, and the Anderson Intelligencer)that shows only references to the Charleston catastrophe, and no mention of any earthquake activity near Abbeyville or Anderson. Given this information, the record appears to be a duplicate of TMP01738, The recommendation is to remove the earthquake from the catalog as a separate earthquake.

TMP02019, 1886/10/22, E[MI 4.13.

Review of the data indicates that TMP02019 is likely a duplicate of TMP02024 and that the time for event TMP02024 should be changed to 10:25 UTC. Bakun and Hopper (2004) studied this event using the intensity data from Talwani and Sharma (1999) and obtained an offshore Charleston location. Recommendation is to remove TMP02019 from the catalog and use the Charleston location in SUSN and the estimated moment magnitude given in Bakun and Hopper (2004) for TMP02024.

TMP02025, 1886/10/22, EfMi 4.13.

Bakun and Hopper (2004) studied this event using the intensity data from Talwani and Sharma (1999) and obtained an offshore Charleston location. Recommendation is to use the Charleston location in SUSN and the estimated moment magnitude given in Bakun and Hopper (2004) for TMP02025.

TMP02360, 1888/1/12, EIMi 4.33.

The location for this event was taken from the USGS. Donald Stevenson and Predeep Talwani (written communication, February 19, 2014) indicate that there are no newspaper reports that support a location between Sumter and Darlington (34.18 -81.17) and that the correct time should be 14:55 UTC. The event may be a duplicate with TMP39326, with a reported time of 15:54 in SUSN and a Charleston location. Recommendation is to remove TMP02360 from the catalog.

Our review turned up another potential duplicate. Bakun and Hopper (2004) also studied the Charleston aftershock on 1886/11/5 17:20 and found a location near Charleston, but slightly inland from other locations. Talwani and Sharma (1999) also concluded that this earthquake occurred at a slightly different location than other Charleston aftershocks. This earthquake appears in the Rev 7 catalog as TMP02071. There is also an event TMP02072 that is listed in the USGS catalog with time 12:25 with a location to the northwest of Charleston. Both events were flagged as Charleston aftershocks in the declustering, but the timing suggests that they may be duplicates. The recommendation is to remove TMP02072 and use the magnitude and location given in Bakun and Hopper (2004) for TM P02071.

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2.1 REFERENCES

Bakun, W.H. and M.G. Hopper, 2004, Magnitudes and Locations of the 1811-1812 New Madrid, Missouri, and the 1886 Charleston, South Carolina, Earthquakes, Bulletin of the Seismological Society of America, 94, 64-75.

Stevenson, D. and P. Talwani, 2014, written communication to Robert Youngs, February 19, 2014.

Munsey, J., 2010, Written communication to Robert Youngs, March 17, 2010.

Talwani, P. and N. Sharma, 1999, Reevaluation of the Magnitudes of Three Destructive Aftershocks of the 1886 Charleston Earthquake, Seismological Research Letters, 70(3), 360-367.

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PART 3 DEVELOPMENT OF A REV 8 CATALOG The assessments in Parts 1 and 2 were used to create a Rev 8 CEUS SSC catalog specifically for calculating earthquake recurrence rates in the southeastern US.

3.1 REVISED ASSIGNMENTS OF PARAMETERS FOR 1886 CHARLESTON ERA EARTHQUAKES The above assessment that, six of the earthquakes listed in Table 6 should be either removed from the catalog as duplicates of other earthquakes or relocated to the vicinity of the1886 Charleston mainshock prompted a further review of the earthquake locations provided by Seeber and Armbruster (1987). The Seeber and Armbruster (1987) locations and size assessments were incorporated into the NCEER-91 catalog and then into the USGS catalog that was used as the primary source for the CEUS SSC Rev 7 catalog. The original Seeber and Armbruster (1987) listing was also incorporated into the CEUS SSC Rev 7 catalog, along with their listed values of felt area.

Seeber and Armbruster (1987) categorized the 1886 Charleston era earthquakes into 5 categories. Reexamination of Seeber and Armbruster (1987) indicated that the earthquakes in their Category 1 and Category 2 had nominal felt areas assigned to them (100 km 2). As these were not actual felt areas assessed from the distribution of felt reports, it was judged that they should not be used to assess magnitude using the models developed in NUREG-2115 based on actual felt areas, and the values of In(FA) were removed from the Rev 8 catalog for the purpose of magnitude assessment.

The Seeber and Armbruster (1987) Category 3 earthquakes are defined as

"...(3) events apparently reported from more than one town, but which are unreliable because large populated areas between these towns did not report feeling the event ... "

The interpreted mislocated events TMP01731 and TMP01739 are listed as Category 3 in Seeber and Armbruster (1987).

Seeber and Armbruster (1987) assigned felt areas as follows:

"The felt areas assigned to events felt at less than 5 towns was the area of the circle with diameter equal to the distance between the most distant felt reports. The felt area assigned to events felt at 5 or more towns is the area of the ellipse with a major axis equal to the distance between the most distant felt reports and a minor axis twice the distance from the major axis to the furthest felt report."

The description of Category 3 events as "unreliable" and having large areas without felt reports between towns with felt reports indicates that the assigned felt areas for these events may also be unreliable. In many cases, the maximum intensity for Category 3 events is II or Ill. Figures 19, 20, and 21 compare the lo and ln(FA) values for Category 3, 4, and 5 earthquakes, respectively from Seeber and Armbruster (1987) with the data from other earthquakes in the Amec Foster Wheeler XA18000s\1 801803000_REPORTS TO 35 CLIENT'CEUS_SSCCatalog_Update_042315\CEUSSSCCatalogUpdate 04_23_201 5.docx

Rev 7 CEUS SSC catalog. The values of In(FA) for Category 3 appear to be biased high for the assigned 10 compared to the general population. Given the evident bias and the unreliability of the events, the Seeber and Armbruster Category 3 events that are duplicated by SUSN events are removed from the Rev 8 catalog and for those Category 3 events that are not duplicated, the values of In(FA) are removed from the Rev 8 listing for use in magnitude assessment.

The comparisons for the Category 4 earthquakes on Figure 20 show general consistency in the Io-ln(FA) data with the rest of the catalog. Many of the Category 4 earthquakes have locations near Charleston. These events are left in the catalog.

The remaining question is the large number (about 25) of the Category 5 earthquakes. A number of these have SUSN entries with the same time, but often significantly different locations. Category 5 is considered by Seeber and Armbruster (1987) as the best located. Five of the interpreted mislocated earthquakes discussed in Part 2 are Category 5 earthquakes, indicating that there are issues with some of these locations. In addition, the data shown on Figure 21 indicate that the assigned In(FA) may be biased high for this category. These events were examined again in comparison to other events in the catalog from SUSN.

Where the Seeber and Armbruster (1987) error ellipses include the SUSN locations, the SUSN locations were used as the primary location. Clearly not all of these earthquakes occurred exactly in the same place. In many cases, the NCEER-91 locations differ from the Seeber and Armbruster (1987) locations and sometimes appear to be an average of the two. The bias in the lo-1n(FA) data for these events and the location bias for the six large events initially identified further suggests that the SUSN locations be used in place of the Seeber and Armbruster (1987)

/ NCEER-91 locations. For those events that could not be associated with an SUSN event, have very large error ellipses, and lo-ln(FA) assessments that appear biased, the In(FA) data were removed from the catalog for magnitude assessment.

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12 Fiur 1:CopaisnofInFA-o at orCaegr 3Eathuke fomSebr n 10-- -

8 .6 44) 6 *NonSeeber and Armbruster (1987)

E

04 40" assessments

E 4O -Seeber and Armbruster Category 3 2 0*

0 0 5 10 15 20 In(Felt Area sq kin)

Figure 19: Comparison of In(FA)-I0 data for Category 3 Earthquakes from Seeber and Armbruster (1987) with data from other earthquakes from the CEUS SSC Rev 7 catalog.

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FigureComparison 20: of ln(FA)-I0 data for Category 4 Earthquakes from Seeber and I T 7 12 10

7 S6 -. m..... g *Non Seeber and Armbruster (1987)

E* 6 1, -assessments E 0 *- OSeeber and Armbruster Category 4 044 0

0 5 10 15 20 In(Felt Area sq kin)

Figure 20: Comparison of In(FA)-I0 data for Category 4 Earthquakes from Seeber and Armbruster (1987) with data from other earthquakes from the CEUS SSC Rev 7 catalog.

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12 10 #

4 C 4*

E 6 4W *Non Seeber and Armbruster (1987) assessments E ASeeber and Armbruster Category 5 4

4

4 muI

4M*

0 0 5 10 15 20 In(Felt Area sq kin)

Figure 21: Comparison of ln(FA)-Io data for Category 5 Earthquakes from Seeber and Armbruster (1987) with data from other earthquakes from the CEUS SSC Rev 7 catalog.

After making the adjustments described above, catalog declustering was performed. As a result, the classification of nine additional earthquakes at locations distant from Charleston significant to hazard (E[M]>2.9) were changed from dependent to independent. Previously, these earthquakes had been classified as dependent earthquakes in clusters associated with the earthquakes identified above. The information for each of these earthquakes was reviewed, including additional information provided by Stevenson and Talwani (written communication, Feb 26, 2014). These events are discussed below.

TMP01942. 1886/9/28. E[M1 3.10.

This is a Category 4 earthquake in Seeber and Armbruster (1987) and is listed in NCEER-91. Its lo (111)and In[FA] (8.0) are consistent with the general population of CEUS SSC earthquakes (see Figure 20). However, Stevenson and Talwani (written communication, 2014) state:

"This is one of the events listed by Seeber and Armbruster that we term to be phantom events. We can find no support or validation for the event or the location. The Union newspaper was not available for this date.

However, a check of other papers in the region (The nearest at Greenville, SC approx. 40 miles away) showed no mention of an earthquake in Union, South Carolina on September 28. The Greenville Amec Foster Wheeler X\LI8000s\1e80180C3000aREPORTS TO 39 CLIENT\CEUSSSC Catalog_Updateý_042315\CEUS SSC Catalog_Update_04_23 2015,docx

paper contained articles related to the Charleston event but no mention of anything in the upstate. We do not believe this to be a genuine event."

Recommendation is to consider this a false event.

TMP02002, 1886/10/12, E[M1 3.04.

Although this event was listed as a category 4 earthquake in Seeber and Armbruster (1987), it was not carried forward into NCEER-91. Also the In(FA) of 8.46 is anomalous compared to the lo of II (Figure 20). The recommendation is to not use the felt area reported by Seeber and Armbruster (1987), which will result in the event not being considered in estimation of earthquake recurrence.

TMP02068, 1886/11/04, EWM] 3.18.

Although this event was listed as a category 4 earthquake in Seeber and Armbruster (1987), it was not carried forward into NCEER-91. Also the ln(FA) of 8.92 is anomalous compared to the lo of II (Figure 20). The recommendation is to not use the felt area reported by Seeber and Armbruster (1987), which will result in the event not being considered in estimation of earthquake recurrence.

TMP02134, 1886/12/08, E[M] 2.82.

This event was listed as a category 2 earthquake in Seeber and Armbruster (1987) and was not carried forward into NCEER-91. Munsey (2006) also identified the event from archival data with a 10 of IV/V similar to the 10 of IV reported in Seeber and Armbruster (1987). Stevenson and Talwani (written communication, Feb 26, 2014) indicate:

... close review of the Columbia Daily Record for the time period of 12/08/1886 to 12/13/1886 showed no reports of felt earthquakes in Columbia. We do not believe this to be genuine."

Based on this assessment, and the fact that the earthquake only potentially affects recurrence calculations because of the 10 assignment of IV/V, it is suggested that this earthquake be considered as either a false event or too small to include in recurrence calculations. The event was retained in Rev 8 of the CEUS SSC catalog with E[M] 2.82.

TMP02136, 1886/12/11, E[M] 3.25.

This is a Category 5 earthquake in Seeber and Armbruster (1987) and is listed in NCEER-91. Its lo (IV) and In(FA) (8.22) are consistent with the general population of CEUS SSC earthquakes (see Figure 21). Stevenson and Talwani (written communication, Feb 26, 2014) indicate:

"The listed location for this event plots just east of Abbeville, SC. This, may be a real event. In the December 13, 1886 edition of the Abbeville Press and Banner a short piece addressing a loud noise heard on the Saturday before (12/11) appeared.

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heard the noise, sound, explosion or whatever it may have been last Saturday afternoon. Mr. A.E. Lewis says it was in the air from him at an angle of 45 degrees a little south of west. Mr. T. L. Haddon says it sounded as if it was over and beyond his gin house."

From this description it is unclear if this was an earthquake or not.

Nothing is mentioned about people feeling the ground move, only about a loud sound. No mention of this event could be found in the Columbia Daily Register, Edgefield Chronicle, or Laurens Advertiser. We feel it doubtful that this is a real earthquake as all mentions above are to noises If this event were to be given the benefit of doubt and accepted as a genuine earthquake, the above, Abbeville, account would lend itself to an assigned intensity considerably less than IV and should probably not be considered. "

The above description indicates that the event may be real. Classification as Category 5 earthquakes in Seeber and Armbruster (1987) indicates that the earthquake was reported in multiple towns. As there is some evidence for the earthquake, there is no clear reason to discount it, and the recommendation is to retain it in the catalog.

TMP02173, 1887/01/12, EIM1 2.91.

This is a Category 4 earthquake in Seeber and Armbruster (1987) and is listed in NCEER-91. Its 10 (111)and In(FA) (7.09) are consistent with the general population of CEUS SSC earthquakes (see Figure 20). Stevenson and Talwani (written communication, Feb 26, 2014) indicate:

"This event plots just outside Due West, SC. between Greenwood and Anderson. Checking issues of the Anderson Intelligencer and Abbeville Press and Banner through the remainder of January 1887 showed a report of a small earthquake near Due West, SC. However, it is reported to have occurred on 01/05/1887. This little event seems to have escaped all catalogers. There is nothing reported for 01/12/1887. From the Abbeville Press an Banner: CHICKASAWS CHIT CHAT; from Due West, SC Jan. 10 1887: "A very perceptible shock of earthquake was felt here last Tuesday morning. Some persons have thought that shocks have been occurring quite frequently for several weeks, but not until last week have they had the bravery to speak positively as to their occurrence."

The above description indicates that this was likely a small earthquake. The assessment of felt area by Seeber and Armbruster (1987) is only approximate, and places this earthquake at the edge of being included in recurrence calculations (E[M] > 2.91). The recommendation is to maintain this earthquake in the catalog without modification..

TMP02393, 1888/04/05, E[M] 4.3.

This event was identified by Munsey (2006). Its size was assessed on the basis of an assigned intensity of VINII, which were described by Munsey (2006) as being very localized effects. The fact that the event was not reported in Seeber and Armbruster (1987) indicates that the high local effects were not widespread. Stevenson and Talwani indicate:

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To our knowledge this event appears in no other catalog except the CEUS-SSC catalog. The location of the event plots just 5 miles south east from the center of Newberry, SC. In checking copies of the Newberry Herold and News for the month of April 1888 we could find no mention of an earthquake anywhere near Newberry. There was only a mention of an earthquake that apparently occurred in China. A check of the Abbevilile Press and Banner, the Edgefield Advertiser, and the News and Herald (Winnsboro,SC) for the month of April, 1888 showed no mention of any earthquakes other than the one in China also appearing in the Newberry paper."

Given that the effects identified by Munsey (2006) are very localized and other investigators did not identify effects on this date in surrounding areas indicates that ifthis was an earthquake, it was likely small. Therefore, the recommendation is to consider this potential event to be too small to affect recurrence calculations.

TMP02423, 1888/08/15, E[MI 3.12.

This is a Category 4 earthquake in Seeber and Armbruster (1987) and is listed in NCEER-91. Its 10 (IV) and In[(A) (7.55) are consistent with the general population of CEUS SSC earthquakes (see Figure 20). Stevenson and Talwani (written communication, Feb 26, 2014) indicate:

"This is, in fact a real event although the listed intensity may be a bit on the high side. It is actually kind of an interesting little read. It apparently occurred in or near Winnsboro, South Carolina. Two mentions of it appeared in the Augusta Chronicle (Augusta Georgia). The first appeared in the August 17, 1888 issue: "NOT AN EARTHQUAKE: Itwas rumored on the streets Wednesday night that an earthquake had been felt at Winnsboro, SC, but it was too late to verify the report by telegraphic advises. It turns out that the report was started by the telegraph operator there who heard a terrific roar and rumbling, accompanied by a rattling of windows and shaking of houses. He told the operators over the wires that there was an earthquake going on and then left the office in haste. A coal burning locomotive of the R & D. road was at the station and the noise was caused by the engineer putting on the blowers."

... Three days later a letter appears in the August 20 issue of the Augusta Chronicle with the headline "KNOWS WHAT A QUAKE IS The Telegraph operator at Winnsboro Has Something to Say of a Shock". "In justice to myself I must ask space in your columns to correct this: I will briefly state the facts in the case: 1 st. On August 1 5 th (Wednesday) a very decided earthquake shock was here at 6:25 p. m., standard time, not only by myself but by the entire population of our town. The duration of the shock was about twenty seconds, accompanied by the usual roaring noise. All the inhabitants can make affidavits to the effect, if necessary. 2 nd I asked only two operators by wire if they felt the shock, they being Ridgeway and Columbia. 3 rd I did not leave my office during the tremor which was very perceptible and quietly remained and noted the time. 4 th The passenger train, south had left Winnsboro about twenty minutes after the earthquake occurred, and there was no "coal burning locomotive" within 18 to 20 Amec Foster Wheeler 42 X:\18000s\180180\3000_REPORTS TO CLIENT\CEUSSSCCatalogUpdate_042315\CEUSSSCCatalogUpdate 04_23 2015.docx

miles of my office. 5 th I have been in the railroad service about ten years and I think this is sufficiently log to enable me to distinguish the roaring sound which accompanies an earthquake from that of a "coal burning locomotive." 6 th A special dispatch announcing the earthquake was sent to the Charleston World. Our county paper also announced the occurrence. 7 th I am a man of veracity, if I do say it myself, and I am not a "nervous operator."

J.H. Skinner; ticket agent and operator.

Upon review of the News and Herald (Winnsboro, SC) only a very short mention was found in the August 22, 1888 issue: "An earthquake shock was felt by some people on Wednesday. The shock was not generally noticed." While this obviously is a genuine event it seems would seem the reported intensity might be a high.

Because the earthquake is clearly identified in the above reporting, the recommendation is to retain it in the catalog with the reported size measures given in Seeber and Armbruster (1987).

The following table summarizes the assessments of the larger events in the Rev 7 catalog that are located at sufficient distance from Charleston to not be identified as aftershocks of the 1886/09/01 main shock.

TABLE 7 REVISED LOCATIONS AND UNIFORM MAGNITUDES FOR SPECIFIC EARTHQUAKES NEAR CHARLESTON, SC TMPID yr Mo Dy Hr Mn sec lat Ion Basis of Revised Magnitude TMP01089 1860 1 19 23 0 0 33.68 -80.57 Move to Charleston and base E[M] on lo Event removed from catalog as a duplicate of TMP01732.

g t of TMP01731 1886 9 1 6 0 0 33.91 -82.02 a ta nduma Location and magnitude of TMP01732 do not require modification Event removed from catalog TMP01739 1886 9 1 14* 45 0 34.04 -82.9 as a duplicate of TMP01738.

Location and magnitude of TMP01738 do not require modification TMP01942 1886 9 28 3 0 0 34.7 -81.62 Consider as a false event TMP02002 1886 10 12 11 0 0 34.14 -81.33 Not use reported felt area, event becomes

°.....

....... < E[M]

E..

.....2.9 TMP02019 1886 10 22 5 0 0 34.71 -81.66 Event removed from catalog as a duplicate of TMP02023 TMP02023 1886 10 22 10 20 32.9 -80 Magnitude taken from Bakun

....... and...........

Ho p.e.r......(2004)

Hopper .20%

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TABLE 7 REVISED LOCATIONS AND UNIFORM MAGNITUDES FOR SPECIFIC EARTHQUAKES NEAR CHARLESTON, SC TMPID yr Mo Dy Hr Mn sec lat Ion Basis of Revised Magnitude TMP02024 1886 10 22 10* 25 33.69 -81 Event removed from catalog as a duplicate of TMP02023 Location moved to TMP02025 1886 10 22 14 45 0 33.87 -81.01 Charleston, magnitude taken from Bakun and Hopper (2004)

TMP02068 1886 11 5 5 0 0 33.38 -82.49 Not use reported felt area, e.n.......becomes.<..........

event E(M] ... .2-................

2.9 TMP02071 1886 11 5 17 20 0 32.9 -80 Magnitude taken from Bakun and Hopper

.......... . . .... .... (2004)

TMP02072 1886 11 5 12 25 33.4 -80.42 Event removed from catalog as a duplicate of TMP02071.

TMP02134 1886 12 8 10 25 0 34.039 --80.886 Revise 10from 4.5 to4 TMP02136 1886 12 11 21 0 0 34.18 -82.06 Retain as is TMP02173 1887 1 12 11 0 0 34.35 -82.42 Retain as less than E[M] 2.9, remove felt area TMP02210 1887 3 4 10 0 0 33.74 -81.5 Not use reported felt area, event becomes < E[M] 2.9 TMP02360 1888 1 12 9 55 0 34.18 -80.17 Event removed from catalog as a duplicate of TMP39326.

TMP02239.

1888 4 5 0 0 0 34.21 -81.534 Retain, reduce to 4, io E[M]

TMP02439 less than 2.9

.....-- 4.......4........

4-- --f...4........

1888 8 15 23 30 0 34.37 -81.08 Retain as is

Change in hour The review described above indicates that considerable uncertainty remains about the parameters of the 1886 Charleston earthquake aftershocks in the published literature. It is suggested that efforts be considered to support publishing the compilation of data on these earthquakes being developed by Don Stevenson and Dr. Pradeep Talwani to aid in further assessments of the earthquakes of this time period.

3.2 CATALOG PROCESSING After revising the parameters of the Charleston aftershocks and removal of the RIS earthquakes, the updated catalog was processed in the same manner as the Rev 7 catalog.

Magnitudes based on lo and In(FA) of the Charleston aftershocks were recalculated using the updated metadata. These calculations were performed using the Rev 7 set of relationships and 10-M and In(FA)-M data in order to produce the same conversions as the Rev 7 catalog. This Amec Foster Wheeler 44 X:T18000s\180180\3000_REPORTS TO CLIEN1\CEUSSSCCatalog_Update_042315\CEUSSSC_Catalog_Update_04_23_2015.docx

was because some of the RIS earthquakes contributed to the conversions and their removal would produce slight differences in the calculated values.

After developing the updated E[M] catalog, it was declustered using the same procedure. The declustering program uses random number generation as part of the selection of which earthquakes to flag as dependent, therefore the updated declustered catalog was edited to utilize the same set of independent and dependent earthquakes as Rev 7 in areas not affected by the catalog updates in order to not introduce small differences in completeness due to this statistical fluctuation.

Completeness was then calculated for the entire region. The primary completeness regions affected were 5, 6, 7, and 12. The differences in completeness are generally less than 5 percent.

3.3 REFERENCES

Seeber, L. and J.G. Armbruster, 1987, The 1886-1889 Aftershocks of the Charleston, South Carolina, Earthquake: a Widespread Burst of Seismicity, Journal of Geophysical Research, 92(B3), 2663-2696.

Stevenson, D. and P. Talwani, 2014, written communication to Robert Youngs, February 26, 2014.

Munsey, J.W., 2006, Identification of "New" Historic Earthquakes in the Central and Eastern United States through Online Keyword Searches: Unpublished Report of River Operations, Tennessee Valley Authority, February.

Amec Foster Wheeler X:\18000s\180180\3000_REPORTS TO 45 CLIENTRCEUSS$CCatalog_Update_O42315\CEUS_SSCCatalogUpdate 04_23_2015.docx

amec foster wheeler APPENDIX A Donald Stevenson to Dr. Youngs Emails

a. Email dated 2/19/2014, 10:54 AM

b. Email dated 2/26/2014, 9:07 AM

Cox, Domonigue C From: donald.stevenson@srs.gov Sent: Wednesday, February 19, 2014 10:54 AM To: Youngs, Bob Cc: pradeep@sc.edu

Subject:

Re: South Carolina earthquakes Attachments: CharlestonareaEqs.xlsx

Bob, We have re-evaluated all of these events by doing an archival search of newspapers in the listed epicentral areas of each event. Our conclusion is that there should be only six earthquakes (one is a repetition), and that all of them occurred in the Charleston/Summerville region. Our revised locations are given in the attached table.

REVISED TABLE BASED ON AN EVALUATION OF CONTEMPORARY ARCHIVAL DATA, PLEASE SEE ATTACHED FILE Some of our detailed information supporting table changes follow:

1. TMP01089: It is in fact a Charleston event, based on the macroseismal data listed by Bollinger and Visvanathan, and a review of newspaper accounts throughout the region. These data clearly point to a Charleston/Summerville source. Below is an Isoseismal map interpreted from Bollinger and Visvanathan (1977).

Bollinger, G.A., Visvanathan, T.R. (1977), The seismicity of South Carolina prior to 1886, in Rankin, D.W., ed., Studies related to the Charleston, South Carolina, earthquake of 1886 - preliminary report:

U.S. Geological Survey Professional Paper 1028-C, p. 33 - 42.

2. TMP01731 and TMP01732: These are two listings of the same event. The coordinates listed for TMP01 732 are correct and supported by archival data, which do not support the mid-state location listed for TMP01 731. TMP01731 has been removed from our corrected list. Based on the archival data this is a Charleston event.

3. TMP01739: Another Charleston event. This event actually occurred at 14:45 UTC. The 09:45 time originated from a list by Seeber and Armbruster (1987) where EST were used. Somewhere in its incorporation, the 9.45 time was listed as being UTC. It took place mere hours after the main Charleston event, and is listed as being just over the Georgia South Carolina border in a relatively remote area of Georgia (even today) 46 km northwest of Abbeyville, and 30 km southwest of Anderson over 300 km northwest of Charleston/Summerville area. Examination of the two closest newspapers to the reported location (Abbeville Pressand Banner, and the Anderson Intelligencer) shows only references to the Charleston catastrophe, and no mention of any earthquake activity near Abbeyville or Anderson. The listed location is incorrect, and has been corrected in our revised table.

4. TMP02019 and 02025: These are two aftershocks of the Charleston earthquake. They were felt over a wide area. The macroseismal data were evaluated by Talwani and Sharma (1999), who located it in the Summerville area and revised the magnitude estimates.. Isoseimal data for these earthquakes and the revised locations by Talwani and Sharma are shown on the maps below taken from that paper, and compared with the WRONG locations (red stars) listed in the existing catalog.

Talwani, P., N. Sharma (1999), Seismological Research Letters, Volume 70, Number 3, 360-367. Red stars are erroneous CEUS SSC locations 2

Ocaobv22. leUS tOZ VTC Oco~2L IMW IVA4UTC

5. TMP02360: This is another mis-located Charleston event. It is incorrectly listed as having occurred at 09:55 EST. This event appears in regional newspaper reports as occurring at times varying from 09:52 to 10:05 EST. Converting to UTC the time becomes 14:52 or there about, a time coincides with a larger Charleston event. This earthquake actually occurred in the Charleston Summerville area and was widely reported throughout the region. However, there are no newspaper reports that support a location between Sumter and Darlington (34.18 -81.17). Its correct location near Summerville has been incorporated in our list above.

In summary, a careful perusal of contemporary newspaper accounts of the dates and times of earthquakes in your list, whose coordinates suggest that they occurred all over South Carolina, were all located in the Summerville Charleston area. The correct times and locations have been given in our revised list.

Original Table:

3

Thank you Don Stevenson and Pradeep Talwani From: "Youngs, Bob" <Bob.Youngs@amec.com>

To: "donaid.stevenson@srs.gov" <donald.stevenson@srs.gov>, "pradeep@sc.edu" <pradeep@sc.edu>,

Date: 02/14/2014 07:43 PM

Subject:

South Carolina earthquakes

Dear Don:

We are looking into some of the South Carolina earthquakes that remain in the CEUS SSC catalog. When you and Pradeep performed your review of the preliminary catalog, you indicated that you were in the process of preparing a study of the earthquakes. I was wondering if you have results for specific earthquakes you could share with me. The specific earthquakes are listed in the attached Excel file with their CEUS SSC id numbers. Any additional information you could provide would be greatly appreciated.

Thank you.

Bob Youngs AMEC Environment & Infrastructure Oakland, California 510-663-4231 510-381-5567 (cell) bob.youngs@amec.com The materials transmitted by this electronic mail are confidential, are only for the use of the intended recipient, and may also be subject to applicable privileges.

Any dissemination, distribution, or copying of this communication is strictly prohibited. If you have received this communication in error, please immediately notify the sender. Please also remove this message from your hard drive, diskette, and any other storage device.

The information contained in this e-mail is intended only for the individual or entity to whom it is addressed.

Its contents (including any attachments) may contain confidential and/or privileged information.

If you are not an intended recipient you must not use, disclose, disseminate, copy or print its contents.

If you receive this e-mail in error, please notify the sender by reply e-mail and delete and destroy the message.

[attachment "CharlestonareaEqs.xlsx" deleted by Donald Stevenson/SRNS/Srs]

4

Cox, Domonique C From: donald.stevenson@srs.gov Sent: Wednesday, February 26, 2014 9:07 AM To: Youngs, Bob Cc: pradeep@sc.edu

Subject:

RE: South Carolina earthquakes Attachments: AdditionalCharlestonareaEqs.xlsx Bob, These events were also included in our extensive archival search of newspapers in reviewing listed epicentral areas of each event. Our conclusion as is that there should be only two or maybe three earthquakes. We could find no mention of a Due West event on January 12, 1887. However, there was a small mention of a 'perceptible' earthquake in Due West on 01/05/1887. Not sure what you might want to do with that one as it looks to be pretty small.

REVISED TABLE BASED ON AN EVALUATION OF CONTEMPORARY ARCHIVAL DATA, PLEASE SEE ATTACHED FILE Some of our detailed information supporting table changes follow:

TMP01942:1886/09/28 This is one of the events listed by Seeber and Arbruster that we term to be phantom events. We can find no support or validation for the event or the location. The Union newspaper was not available for this date. However, a check of other papers in the region (The nearest at Greenville, SC approx. 40 miles away) showed no mention of an earthquake in Union, South Carolina on September 28. The Greenville paper contained articles related to the Charleston event but no mention of any thing in the upstate. We do not believe this to be a genuine event.

TMP02134:1886/12/08 This is another unverifiable event. While it does appear in Seeber and Armbruster (1987) it was not included in the original NCEER/EPRI (1991) catalog. We interpret this to us that it may have been judged a little too small to make the cut for 1991. However, Jeff Munsey seems to have picked it up, come up with a larger intensity and submitted it for consideration in the CEUS catalog. The plotted location is Columbia, SC. Whatever the case close review of the Columbia Daily Record for the time period of 12/08/1886 to 12/13/1886 showed no reports of felt earthquakes in Columbia. We do not believe this to be genuine.

TMP02136:1886/12/11 The listed location for this event plots just east of Abbeville, SC. This, may be a real event. In the December 13, 1886 edition of the Abbeville Press and Banner a short piece addressing a loud noise heard on the Saturday before (12/11) appeared.

""The Noise on Saturday: Many persons in the vicinity of Abbeville heard the noise, sound, explosion or whatever it may have been last Saturday afternoon. Mr. A.E. Lewis says it was in the air from him at an angle of 45 degrees a little south of west. Mr. T. L. Haddon says it sounded as if it was over and beyond his gin house."

From this description it is unclear if this was an earthquake or not. Nothing is mentioned about people feeling the ground move, only about a loud sound. No mention of this event could be found in the Columbia Daily Register, Edgefield Chronicle, or Laurens Advertiser. We feel it doubtful that this is a real earthquake as all mentions above are to noises If this event were to be given the benefit of doubt and accepted as a genuine earthquake, the above, Abbeville, account would lend itself to an assigned intensity considerably less than IV and should probably not be considered.

TMP02173:1887/01/12 This event plots just outside Due West, SC. between Greenwood and Anderson. Checking issues of the Anderson Intelligencerand Abbeville Pressand Banner through the remainder of January 1887 showed a report of a small earthquake near Due West, SC. However, it is reported to have occurred on 01/05/1887. This little event seems to have escaped all catalogers. There is nothing reported for 01/12/1887.

From the Abbeville Press an Banner CHICKASAW'S CHIT CHAT; from Due West, SC Jan. 10 1887: "A very perceptible shock of earthquake was felt here last Tuesday morning. Some persons have thought that shocks have been occurring quite frequently for several weeks, but not until last week have they had the bravery to speak positively as to their occurrence." Not really sure what you may want to do about this one.

TMP02393:1888/04/05 To our knowlege this event appears in no other catalog except the CEUS-SSC catalog. The location of the event plots just 5 miles south east from the center of Newberry, SC. In checking copies of the Newberry Herold and News for the month of April 1888 we could find no mention of an earthquake anywhere near Newberry. There was only a mention of an earthquake that apparently occurred in China. A check of the Abbevillle Press and Banner, the Edgefield Advertiser, and the News and Herald (Winnsboro,SC) for the month of April, 1888 showed no mention of any earthquakes other than the one in China also appearing in the Newberry paper. We would be interested to know where Jeff Munsey got his information on this event as there is nothing in that location to suggest an earthquake let alone something as large as a VINII.

TM P02423:188/08/15 This is, in fact a real event although the listed intensity may be a bit on the high side. It is actually kind of an interesting little read. It apparently occurred in or near Winnsboro, South Carolina Two mentions of it appeared in the Augusta Chronicle (Augusta Georgia). The first appeared in the August 17, 1888 issue:

"NOT AN EARTHQUAKE: It was rumored on the streets Wednesday night that an earthquake had been felt at Winnsboro, SC, but it was too late to verify the report by telegraphic advises. It turns out that the report was started by the telegraph operator there who heard a terrific roar and rumbling, accompanied by a rattling of windows and shaking of houses. He told the operators over the wires that there was an earthquake going on and then left the office in haste. A coal burning locomotive of the R & D. road was at the station and the noise was caused by the engineer putting on the blowers."

But wait, three days later a letter appears in the August 20 issue of the Augusta Chronicle with the headline "KNOWS WHAT A QUAKE IS The Telegraph operator at Winnsboro Has Something to Say of a Shock".

"In justice to myself I must ask space in your columns to correct this: I will briefly state the facts in the case:

1 st. On August 1 5 th (Wednesday) a very decided earthquake shock was here at 6:25 p. m., standard 2

time, not only by myself but by the entire population of our town. The duration of the shock was about twenty seconds, accompanied by the usual roaring noise. All the inhabitants can make affidavits to the effect, if necessary.

2 nd I asked only two operators by wire if they felt the shock, they being Ridgeway and Columbia.

3 rd I did not leave my office during the tremor which was very perceptible and quietly remained and noted the time.

4 th The passenger train, south had left Winnsboro about twenty minutes after the earthquake occurred, and there was no "coal burning locomotive" within 18 to 20 miles of my office.

5 th I have been in the railroad service about ten years and I think this is sufficiently log to enable me to distinguish the roaring sound which accompanies an earthquake from that of a "coal burning locomotive."

6 th A special dispatch announcing the earthquake was sent to the Charleston World. Our county paper also announced the occurrence.

7 th I am a man of veracity, if I do say it myself, and I am not a "nervous operator."

J.H. Skinner; ticket agent and operator Upon review of the News and Herald (Winnsboro, SC) only a very short mention was found in the August 22, 1888 issue: "An earthquake shock was felt by some people on Wednesday. The shock was not generally noticed." While this obviously is a genuine event it seems would seem the reported intensity might be a high.

Hope that this helps.

don and Pradeep Don Stevenson donald.stevenson@srs.gov (803) 725-3568 From: "Youngs, Bob" <Bob.Youngs@amec.com>

To: "donald.stevenson@srs.gov' <donald.stevenson@srs.gov>,

Cc: "pradeep@sc.edu" <pradeep@sc.edu>

Date: 02/24/2014 03:06 PM

Subject:

RE: South Carolina earthquakes

Dear Don and Pradeep:

I very much appreciate your help last week. Moving the identified events back to the Charleston area has resulted in the emergence of six additional earthquakes that may be questioned. These earthquakes are listed in the attached Excel file. I would greatly appreciate it ifyou have any information on these specific events as their locations are too far from Charleston for the declustering approach to identify them as aftershocks of 1886.

Thank you again for any help you can provide.

Bob Youngs AMEC Environment & Infrastructure Oakland, California 510-663-4231 510-381-5567 (cell) bob.youngs@amec.com 3

The materials transmitted by this electronic mail are confidential, are only for the use of the intended recipient, and may also be subject to applicable privileges.

Any dissemination, distribution, or copying of this communication is strictly prohibited. If you have received this communication in error, please immediately notify the sender. Please also remove this message from your hard drive, diskette, and any other storage device.

From: donald.stevenson@srs.gov [maiIto:donald.stevensonbsrs.gov]

Sent: Wednesday, February 19, 2014 10:54 AM To: Youngs, Bob Cc: pradeep@sc.edu

Subject:

Re: South Carolina earthquakes

Bob, We have re-evaluated all of these events by doing an archival search of newspapers in the listed epicentral areas of each event. Our conclusion is that there should be only six earthquakes (one is a repetition), and that all of them occurred in the Charleston/Summerville region. Our revised locations are given in the attached table.

REVISED TABLE BASED ON AN EVALUATION OF CONTEMPORARY ARCHIVAL DATA, PLEASE SEE ATTACHED FILE Some of our detailed information supporting table changes follow:

1. TMP01089: It is in fact a Charleston event, based on the macroseismal data listed by Bollinger and Visvanathan, and a review of newspaper accounts throughout the region. These data clearly point to a Charleston/Summerville source. Below is an Isoseismal map interpreted from Bollinger and Visvanathan (1977).

Bollinger, G.A., Visvanathan, T.R. (1977), The seismicity of South Carolina prior to 1886, in Rankin, D.W., ed., Studies related to the Charleston, South Carolina, earthquake of 1886 - preliminary report:

U.S. Geological Survey Professional Paper 1028-C, p. 33 - 42.

4

2. TMP01731 and TMP01732: These are two listings of the same event. The coordinates listed for TMP01 732 are correct and supported by archival data, which do not support the mid-state location listed for TMP01 731. TMP01731 has been removed from our corrected list. Based on the archival data this is a Charleston event.

3. TMP01739: Another Charleston event. This event actually occurred at 14:45 UTC. The 09:45 time originated from a list by Seeber and Armbruster (1987) where EST were used. Somewhere in its incorporation, the 9.45 time was listed as being UTC. It took place mere hours after the main Charleston event, and is listed as being just over the Georgia South Carolina border in a relatively remote area of Georgia (even today) 46 km northwest of Abbeyville, and 30 km southwest of Anderson over 300 km northwest of Charleston/Summerville area. Examination of the two closest newspapers to the reported location (Abbeville Pressand Banner, and the Anderson Intelligencer) shows only references to the Charleston catastrophe, and no mention of any earthquake activity near Abbeyville or Anderson. The listed location is incorrect, and has been corrected in our revised table.

4. TMP02019 and 02025: These are two aftershocks of the Charleston earthquake. They were felt over a wide area. The macroseismal data were evaluated by Talwani and Sharma (1999), who located it in the Summerville area and revised the magnitude estimates.. Isoseimal data for these earthquakes and the revised locations by Talwani and Sharma are shown on the maps below taken from that paper, and compared with the WRONG locations (red stars) listed in the existing catalog.

Talwani, P., N. Sharma (1999), Seismological Research Letters, Volume 70, Number 3, 360-367. Red stars are erroneous CEUS SSC locations 5

Oclobr22. IS" 10=,2VTC Oobvt 2L Is" lt.46 MT

- Pa ~i~iam.*

5. TMP02360: This is another mis-located Charleston event. It is incorrectly listed as having occurred at 09:55 EST. This event appears in regional newspaper reports as occurring at times varying from 09:52 to 10:05 EST. Converting to UTC the time becomes 14:52 or there about, a time coincides with a larger Charleston event. This earthquake actually occurred in the Charleston Summerville area and was widely reported throughout the region. However, there are no newspaper reports that support a location between Sumter and Darlington (34.18 -81.17). Its correct location near Summerville has been incorporated in our list above.

In summary, a careful perusal of contemporary newspaper accounts of the dates and times of earthquakes in your list, whose coordinates suggest that they occurred all over South Carolina, were all located in the Summerville Charleston area. The correct times and locations have been given in our revised list.

Original Table:

6

_______mo rdy

_hr sec lat Ion dep EM TMP01089 I_ 1860 L. 1~ 19 23] 0 01 33.68 -80.57 0 4.21 TMP01731 _18861 91 61 0 ------ 0 33.91 -82.02 0 4.54 TMP01732 1886i 91 1 61 5 0! 32.9 -80 0 3.93 TMP01739 18861 - §ý f 1 9i 45 0l 34.3 -82.86 0 4-17 TMP02019 1 1886!

{-:

101 221I 5! 0-4 0 34.711 , -81.66 4-- _ 0 4.13 TMP02025 1886L 101 22i 141 45 0 33.87 -81.01 0 4.5 TMP02360 I 1888 1 12, __ 91 55! 0 34.181 -80.17 0 4.33 Thank you Don Stevenson and Pradeep Talwani From: "Youngs, Bob" <Bob.Youngs@amec.com>

To: "donald.stevenson@srs.gov" <donald.stevenson@srs.gov>, "pradeep@sc.edu" <pradeep@sc.edu>,

Date: 02/14/2014 07:43 PM

Subject:

South Carolina earthquakes

Dear Don:

We are looking into some of the South Carolina earthquakes that remain in the CEUS SSC catalog. When you and Pradeep performed your review of the preliminary catalog, you indicated that you were in the process of preparing a study of the earthquakes. I was wondering if you have results for specific earthquakes you could share with me. The specific earthquakes are listed in the attached Excel file with their CEUS SSC id numbers. Any additional information you could provide would be greatly appreciated.

Thank you.

Bob Youngs AMEC Environment & Infrastructure Oakland, California 510-663-4231 510-381-5567 (cell) bob.youngs@amec.com The materials transmitted by this electronic mail are confidential, are only for the use of the intended recipient, and may also be subject to applicable privileges.

Any dissemination, distribution, or copying of this communication is strictly prohibited. If you have received this communication in error, please immediately notify the sender. Please also remove this message from your hard drive, diskette, and any other storage device.

The information contained in this e-mail is intended only for the individual or entity to whom it is addressed.

Its contents (including any attachments) may contain confidential and/or privileged information.

If you are not an intended recipient you must not use, disclose, disseminate, copy or print its contents.

If you receive this e-mail in error, please notify the sender by reply e-mail and delete and destroy the message.

[attachment "Charlestonarea_Eqs.xlsx" deleted by Donald Stevenson/SRNS/Srs]

[attachment "AdditionalCharlestonareaEqs.xlsx" deleted by Donald Stevenson/SRNS/Srs]

7

amec foster wheeler ATTACHMENT 2 Reviews by Dr. Martin Chapman and Dr. Richard Quittmeyer

Memo:

March 5, 2014 John Richards Electric Power Research Institute 1300 West WT Harris Blvd I Charlotte, NC 28262

Subject:

Review of NUREG-2115 Earthquake catalog with regard to identification of additional Reservoir Induced Seismicity (RIS) earthquakes in the southeastern United States and locations of earthquakes in South Carolina near the time of the 1886 Charleston, SC earthquake sequence.

Dear John:

We have completed our review of the CEUS SSC catalog published in NUREG-2115 with regard to two issues: (1) identification of additional reservoir induced seismicity (RIS) earthquakes in the southeastern US and (2): locations of earthquakes in South Carolina near the time of the 1886 Charleston, SC earthquake sequence. The results of that review are described below.

Robert Youngs AMEC Environment & Infrastructure 1

Additional RIS Earthquakes In developing the CEUS SSC catalog, earthquakes identified as RIS were removed from the final earthquake listing. The source for this identification in the southeastern US was the set of available Southeast US Seismic Network (SEUSSN) Bulletins. The master list contained 120 earthquakes. Sixteen of these were large enough to be in CEUS SSC catalog. These earthquakes occurred primarily near Monticello Reservoir and Lake Keowee. These earthquakes were removed from the final (Version 7) CEUS SSC catalog published in NUREG-2115.

At the request of EPRI, we have performed additional reviews of available information to identify potential additional RIS earthquakes that are in the CEUS SSC catalog.

References The following list contains the additional reference material consulted to identify potential RIS earthquakes in the CEUS SSC catalog.

[1] Acree, S.D., Acree, J.R., and P. Talwani, 1988, The Lake Keowee, South Carolina earthquakes of February through July 1986, Seismological Research Letters, 59 (2), 63-70.

[2] Talwani, P.,1981, Earthquake Prediction Studies in South Carolina, in "Earthquake Prediction: An International Review". American Geophysical Union.

[3] Talwani, P., 1990, Appendix D in Krinitzsky, E.L. and J.B. Dunbar (1990): "Geological Seismological Evaluation of Earthquake Hazards at Hartwell and Clemson Upper and Lower Dams, South Carolina". Final Report prepared for US Army Engineer District Savannah, Savannah, Georgia.

[4] Talwani, P., 1997, On the Nature of Reservoir-induced Seismicity, Pure and Applied Geophysics, 150, 473-492.

[5] Talwani, P., Stevenson, D., Amick, D., and J. Chiang, 1979, An Earthquake Swarm at Lake Keowee, South Carolina, Bulletin of the Seismological Society of America, 69 (2), 825-841.

[6] Long, L.T., Kocaoglu, A., Hawman, R., and P.J.W. Gore, The Norris Lake earthquake swarm of June through September, 1993; Preliminary Findings. Seismological Reserarch Letters, 65 (2), 167-171.

[7] Fletcher, J.B., Boatwright, J., and W.B. Joyner, 1983, Depth dependence of source parameters at Monticello, South Carolina, Bulletin of the Seismological Society of America, 73 (6), 1735-1751.

[8] Chen L., and P. Talwani, 2001, Mechanism of Initial Seismicity Following Impoundment of the Monticello Reservoir, South Carolina, Bulletin of the Seismological Society of America, 91 (6), 1582-1594.

[9] Rajendran, K., and P. Talwani, 1992, The role of elastic, undrained, and drained responses in triggering earthquakes at Monticello Reservoir, South Carolina, Bulletin of the Seismological Society of America, 82 (4), 1867-1888.

2

[10] Shedlock, K.M., 1988, Seismicity in South Carolina, Seismological Research Letters, 59 (4),

165-171.

[11] Tarr, A.C., Talwani, P., Rhea, S., Carver, D., and D. Amick, 1981, Results of recent South Carolina seismological studies, Bulletin of the Seismological Society of America, 71 (6), 1883-1902.

[12] Chen L., and P. Talwani, 2001, Renewed seismicity near Monticello Reservoir, South Carolina, 1996-1999, Bulletin of the Seismological Society of America, 91 (1),94-101. r

[13] Marion, G.E., and L.T. Long, 1980, Microearthquake spectra in the Southeastern Und States, Bulletin of the Seismological Society of America, 70 (4), 1037-1054.

Review Results The documents listed above were reviewed to identify specific RIS events. Often the earthquakes are vaguely listed by month and year, without a precise date, or magnitude.

Coordinates usually not listed. As an example: [4], [9], [10], [12] do not list a single individual earthquake. Also, most of the RIS is low magnitude (less than 2), which was typically not included in the CEUS-SSC catalog.

The following sets of lists show all the earthquakes that are reported with a date and occasionally magnitude in the references above. IJ The first list contains earthquakes identified as RIS that were too small to be included in the CEUS SSC Version 7 catalog. [W]

Earthquakes Identified as l-'-hat are not in the CEUS-SSC catalog Ea date Ref 1978/10/27 [7]

1979/1/19 [1]

1976/1/14 [2]

1977/2/23 [2]

1987/12/24 [3]

1988/1/26 [3]

1993/9/23 [6]

Events 1 through 40 and 42 through 53 of Table 1 in [8].

Events in Table 1 of [13].

The second list contains three earthquakes mentioned in the above literature that we consider to have been correctly classified in the Version 7 CEUS SSC catalog.

Earthquakesgorrectly Classified TMP10113, 1979/10/16 M 3.0

[I Ref. [7] analyzed four well recorded reservoir induced earthquakes near the Monticello reservoir to determine stress drop. The events are taken from Fletcher (1982). This earthquake was identified as RIS in the Version 7 CEUS-SSC catalog.

3

TMP14740, 1986/2/13 E[M1 3.32. [ L__

Ref [1] states there is no correlatid.-, tween reservoir level and the onset of seismicity (this event), while rapid fluctuations in the water levels were observed before the subsequent events in June (see below) and July. This earthquake was included in the Version 7 CEUS-SSC catalog as a non RIS earthquake.

TMP14964, 1986/6/11 Md 2.8 This event was identified as RIS in the Version 7 CEUS-SSC catalog from the SEUSSN Bulletins.

The third list contains additional earthquakes described in the above references that were evaluated as potential RIS earthquakes Potential Additional RIS earthquakes in CEUS-SSC Version 7 Catalog J jj*

TMP07012, 1969/12/13, E[M] 3.46 Ref. [5] argues that location of this event is based on "meager macroseismic data" and the earthquake could possibly be a RI event at Lake Keowee. This earthquake is too old to be listed in the SEUSSN Bulletins. Because the event is not clearly identified as RIS in the reference, our recommendation is that it should remain in the catalog as a non RI earthquake.

TMP07159, 1971/7/13, EfM] 3.63 Ref. [5] suggests that the location of the Seneca earthquake by Bollinger (1972) is less accurate than the location by Sowers and Fogle (1978), which is based on detailed macroseismic studies. The Sowers and Fogle (1978) location coincides with observed RIS. This earthquake is too old for the SEUSSN Bulltins. The earthquake appears in a number of catalogs: EPRI, NCEER91, USGS, SEUSSN, South Carolina seismic network, Reagor, Stover and Coffman, and Hopper. Conclusion is that the more precise location suggests that it may be an RI earthquake and the recommendation is to identify as a potential RI earthquake.

TMP07565, 1974/8/2 E[M] 3.91 Ref. [3] says there is excellent correlation between water fluctuations and earthquakes, however admits that "The observation that the seismicity occurred 43 km upstream of the Clarks Hill dam and 22 years after its impoundment led to the questioning of the suggestion that the activity was induced". The earthquake is also mentioned in [11]. This earthquake is too old for the SEUSSN Bulletin. Because Ref [3] questions the categorization of this earthquake as RIS, recommendation is to retain as a non RI earthquake in the catalog.

TMP08078, 1975/11/25 E[M1 3.21 Ref. [11] says that following this earthquake a monitoring program was carried out in the vicinity of Lakes Jocassee and Keowee. This earthquake is too old for the SEUSSN Bulletin and is not in our list of non-tectonic earthquakes. Recommendation is to identify as an RIS earthquake.

TMP08787, 1977/9/7 E[M] 2.77 Ref. [2] says this event was found to be associated with the larger related changes in water levels at a well. This earthquake was not listed in the SEUSSN Bulletin. Recommendation is to identify as an RIS earthquake, although it is smaller that earthquakes used in recurrence calculations.

4

TMP08971, 1978/1/25 E[M1 2.6 This earthquake is #41 in Table 1 of [8]. SEUSSN Bulletin lists the earthquake as 25 January 1978 Jenkinsville, South Carolina, ML 2.8 (USC), Lat 34.3 N, Long 81.3W at 3:29:38.7 and depth of 2 km. A note in parenthesis reads: "Same event as the 8/29/38.9 shock in the microearthquakes in South Carolina listing?" Recommendation is to identify as an RIS earthquake, although it is smaller that earthquakes used in recurrence calculations.

TMP09000, 1978/1/25 E[M] 2.93 This earthquake is not flagged in the SEUSSN Bulletins, but location and shallow depth suggests in may be RIS. Recommendation is to identify as a possible RI earthquake.

TMP09354, 1978/8/27 E[M] 2.93 Not listed in SEUSSN Bulletin. This earthquake is one of the four events studied in [7]. Location is obtained from Fletcher (1982). Recommendation is to identify as an RI earthquake.

2.77 [7-1 TMP09355, 1978/8/27 E[M1 Not listed in SEUSSN Bulletin. Th' e'arthquake occurred immediately after TMP09354 in nearly the same location and was flagged as a dependent even. It has an assigned depth of 7 km, which is much deeper than typical RIS. Recommendation is to identify as a possible RI earthquake, although it is smaller than earthquakes used in recurrence calculations.

TMP09460, 1978/10/27 E[M] 3.08 Not listed in SEUSSN Bulletin. This earthquake is one of the four events studied in [7]. Location is obtained from Fletcher (1982). Recommendation is to identify as a RI earthquake.

TMP10034, 1979/8/26 E[M1 3.64 This is listed in Ref. [2] and was also flagged in the SEUSSN Bulletin. Recommendation is to identify as a RI earthquake.

TMP10104, 1979/10/8 E[M] 3.16 Reexamination of the SEUSSN Bulletin indicates that this event is listed. Recommendation is to identify as a RI earthquake.

TMP10109, 1979/10/14 E[M1 3.08 Reexamination of the SEUSSN Bulletin indicates that this event is listed. Recommendation is to identify as a RI earthquake.

TMP10506, 1980/7/29 ErM 3.31 1M This earthquake was not flagged ýpive SEUSSN Bulletin and its location quality was listed as D.

However, its location and shallow depth makes it a candidate as an RI earthquake.

Recommendation is to consider the event as a possible RI earthquake.

TMP1 6282 1988/1/27 E[M1 2.32 Ref. [3] says activity is typical of reservoir induced sequences. SEUSSN Bulletin lists this event as "possible earthquake". Recommendation is to identify as an RIS earthquake, although it is smaller that earthquakes used in recurrence calculations.

Based on the review of the references [1] through [5], a review of the SEUSSN Bulletins between 1979 and 1980, and examination of the catalog near other events flagged as RI, the following earthquakes are identified as possible RI.

5

cFDF9J TMPID yr mo Dy hr mn Sec lat Ion depth E[M] Comment TMP07012 1969 12 13 10 19 29.7 35.04 -82.85 6 3.46 Speculative, retain as non RIS TMP07159 1971 7 13 11 42 26 34.8 -83 n/a 3.63 Possible RIS TMP07565 1974 8 2 8 52 11.1 33.91 -82.53 4 3.91 Speculative, retain as non RIS TMP08078 1975 11 25 15 17 34.8 34.93 -82.9 10* 3.21 RIS TMP08787 1977 9 7 14 41 32.7 34.982 -82.927 n/a 2.77 RIS TMP08971 1978 1 25 8 29 39 34.301 -81.234 5** 2.6 RIS TMP09354 1978 8 27 10 23 8 34.313 -81.337 2 2.93 RIS

..! M P08.99.8........... 19.78.

.. ......... 28.. 10.20.23.

2............ ...... .......... ......... ....3...... -8.1....................

I ..... 88.. . .........

1 2.77 Possible RIS TMP08999 1978 2 11 0 19 0.7 34.343 -81.35 3 2.77 Possible RIS TMP09000 1978 2 11 5 19 0.2 34.346 -81.349 1 2.93 Possible RIS TMP09006 1978 2 14 12 45 7.2 34.342 -81.346 1 2.93 Possible RIS TMP09007 1978.2.14 13 9 59.5 34.351 -81 .343 2 2.85 Possible RIS TMP09013 1978 2 15 21 14 34.2 34.349 -81.346 0 2.77 Possible RIS TMP09014 1978 2 16 2 14 33.4 34.332 -81 .362 2 2.85 Possible RIS TMP09023 1978 2 22 7 13 25.1 34.327 -81.35 1 2.85 Possible RIS S 1 2 ......................................

2 1 1 4.................

33 3 1.....................

3...............................................00..

-81............................................... Possible..........R.

TMP09025 1978 2 22 13 4 59.2 34.356 -81.352 0 2.77 Possible RIS TMP09027 1978 2 24 7 34 10.5 34.334 -81.348 1 2.93 Possible RIS TMP09029 1978 2 25 4 2 42.7 34.345 -81.351 1 2.77 Possible RIS TMP09031 1978 2 26 6 52 35.4 34.315 -81.297 1 2.85 Possible RIS TMP09032 1978 2 26 11 52 33 34.391 -81.361 1 3.00 Possible RIS TMP09033 1978 2 26 18 17 48.8 34.321 -81.348 0 3.08 Possible RIS TMP09343 1978 8 24 10 23 7.6 34.311 -81.341 2 2.85 Possible RIS TMP09355 1978 8 27 10 23 8 34.313 -81.337 7 2.77 Possible RIS TMP09460 1978 10 27 16 27 18.1 34.302 -81.326 2 3.08 RIS TMP09518 1978 11 24 11 54 40.9 34.296 -81.347 1 2.85 Possible RIS TMP10034 1979 8 26 1 31 45 34.916 -82.956 1 3.64 RIS TMP39374 1979 10 8 8 54 19.4 34.31 -81.33 2 2.85 RIS TMP10104 1979 10 8 23 20 11 34.306 -81.348 1 3.16 RIS TMP09139 1979 10 14 8 24 57.6 34.306 -81.338 2 3.08 RIS TMP10556 1980 7 29 1 10 22.7 34.351 -81.364 1 3.31 Possible RIS TMP16282 1988 1 27 22 5 42.9 34.189 -82.75 6.1 2.32 RIS

depth 17km in RAN.,DJ - - ____ __ __ _ ____

- depth 1 km in Stover & Coffman 6

The figure below shows the location of the earthquakes listed above with respect to the NPPs that are located next to a lake or reservoir. The only two NPPs that are affected by these RIS earthquakes are Oconee and VC Summer.

36PN I Focal depth 4 11' 0 unknown 0 < 2 km .. .. .--- - - - - - -- - - - - - - ----.---

2 - 5 km :Harris 0 > 6km '

McGuire 2&------- ~~~~----------L------------------------------------------

S--- -A :Catawba 4 6 ----- -------- -------

A Oconee 40' Robinson 20VS mA

VC Summer

.3 VV 1'50W 83ew 820w 811W 800W 79PW

(ýD F-0-1 7

Seismicity within 100 km of NPPs in the Southeastern U.S.

An additional step was to examine seismicity in the vicinity of NPPs in the southeast US that are following is a list of NPPs in the Southeastern U.S.: LII near reservoirs to look for potential clusters of earthquakes not presently identified as RIS. The

[ 19 No. Nuclear site Latitude (deg) Longitude (deg) State Nearby LakelRiver 1 Hatch 31.9342 -82.3444 GA Altamaha River 2 Vogtle 33.1419 -81.7647 GA Savannah River 3 Oconee 34.7917 -82.8986 SC Lake Keowee 4 Lee Nuclear 35.0369 -81.5118 SC Broad River 5 Summer 34.2958 -81.3203 SC Monticello Reservoir 6 Catawba 35.0514 -81.0694 SC Lake Wylie 7 Robinson 34.4053 -80.1586 SC Lake Robinson 8 McGuire 35.4322 -80.9483 NC Lake Norman 9 Harris 35.6333 -78.9561 NC Shearon-Harris Reservoir 10 Brunswick 33.9583 -78.0106 NC Coastal (Cape Fear River) 11 Surry 37.1656 -76.6983 VA James River The seismicity within 100 km of these NPPs was pulled from the CEUS SSC earthquake catalog (rev 7) and plotted to identify clusters that might be associated with the reservoirs.

In all figures:

- filled circles are earthquakes occurred after the lake impoundment that are identified as mainshocks;

- filled squares are earthquakes occurred prior to the lake impoundment that are identified as mainshocks;

- open circles and open squares are dependent events (post-and pre-impoundment respectively);

- unknown depths are plotted in blue;

- depths less than 2 km are plotted in red;

- depths between 2 and 5 km are in green;

- depths greater than 5 km are in black;

- the NPP site is shown by a yellow triangle.

8

NPPs Located on Lakes and Reservoirs Oconee There are 155 earthquakes within 100 km of the Oconee NPP. Most of the seismicity pre-1973 has unknown depth (fixed at 0). In Ref [5] the depth of the swarm is limited to the topmost 2 km.

Oconee I

I I

I pre-impoundment

I p I

I I m unknown

I

~'mI I

<2km 30l

" 2-6km

.41.e

V OmnOb U:

U I

>6km post-impoundment 30' WA .~.;a

~.Uu.*L

,~,.xU-a

unknown AJIk

<2 km

2-6km El * > 6 km 34°N I I I*I

I I I t I a *

m 30' a I

I I

I I I

. I

I I

, S I I S I I

S S I

- I 22UM E 84OW 30 83OW 3(r 82ow 30r 8 lW The next figure shows a zoom of the seismicity cluster near the NPP. These earthquakes are likely RIS events from Lake Keowee: they are typically shallow and occurred after the impoundment of the lake, in areas that have no prior seismicity.

P 912 9

Oconee - zoom 3(r _________

0 2(Y - - - - - - - . . . . . - - - - ---

. 10

VC Summer There are 262 earthquakes within 100 km of the VC Summer NPP. The seismicity pre-1968 has unknown depth (fixed at 0). There is a cluster of seismicity very near the NPP, which is associated with the Monticello Reservoir.

Summer W

pre-impoundment m unknown

<2km 35PN " 2-6km

-~0- * >6km lo 0' 0 W~

oost-impoundment

- -- -- - - - -- - -i --

unknown

<2 km

1

2-5km

---- * >5km 34"NK 0 01i E~

30 - 12 0 S I p 0 I I - - -I - - - - - I I--

W NY I I 3(r 82OW Blow 301 80%W 11

Summer - zoom I I pre-Impoundmenlt I

m unknown S<<2km 0 2-5kmn

>Skmn 24 0 post-impoundmen' t 0 unknown 0 0 <2 km

2- 5 km

> 5 km

- -- -- b.- -- -- - -- -- - - - -- -- - -- -

18"

..... *--Z - --------------------------------------------------------...

U0 12' I 3 3 I 24' 18' 12' 8,5w The enlarged figure above shows this cluster in detail: there are two clusters of earthquakes.

One cluster is closer to the NPP (earthquakes have mostly depths of 1 km), and one cluster is further to the north where there are events in the 2-5 km depth range. The figure also shows that most of the earthquakes are removed in the declustering process. The next figure compares the seismicity near the VC Summer NPP to figure 2 of [12] that shows the seismicity in from 15 December 1996 to 31 December 1999. F 3T

1. 12

4*0 344N

. .... . . . . [ . . . . . 34020

"- IV e I I I 6*I I*

Jsc StI 0 1 2 3 4km I I The northernmost cluster is probably in the area of W1; the three earthquakes that are lined up closer to the site have occurred in 1978, 1979 and 1982.

13

Catawba There are 136 earthquakes within 100 km of the Catawba NPP. The seismicity pre-1975 has unknown focal depth. If these earthquakes are removed the nearest earthquake has a depth of 23 km. The NPP is located on Lake Wylie (see figure from google maps): the earthquakes closer to the lake occurred prior to its impoundment. The cluster of earthquakes to the south is about 100 km of distance from the NPP. A search of literature (BSSA and SRL) did not return any specific study of the seismicity of Lake Wylie.

Catawba 36°N pre-impoundment m unknown

--- ----- --- - -- -- - -- -- - * <2 km 40'

2-5km

>5km 20' post-impoundment

unknown

<2km 4--- - - - -- - -- - -- - -

4%

2-5km 35°N

> 5 km 0

40' 20'

-a..~ I C I

- ,W 82oW NY Blow 30r NgoW 14

Robinson There are 134 earthquakes within 100 km of the Robinson NPP, of which 17 (all post 1975) have an estimate of the focal depth. The nearest earthquake to the NPP has unknown depth.

The figure does not show clusters of seismicity associated with Lake Robinson. The two events closest to the NPP are the 1959 Chesterfield County earthquake and an earlier event in 1930 located about 5 km to the west of the 1959 event. The two earthquakes are located based on macroseismic intensities and felt area only, and SEUSSN gives to both earthquakes a location error of 83.4 km. We found no information in the literature on the 1959 earthquake that associates the event to the impoundment of Lake Robinson.

Robinson pre-impoundment 20 -----------.----------- ------------......------------------- m unknown 0 <2km

2-5km 350 N ---------- ----------- 4----------- L > 5 km

' post-impoundment 4 - -. -. -. -

I 40, 0 unknown

- 0 <2km

"*lm! : 02-5km

- ~_ *0 >5km 2*--------------------------------@------

4 ................- ---*- .. . . EE~

82OW 30 81OW N 80W N7SV 15

McGuire There are 46 earthquakes within 100 km of the McGuire NPP, of which 19 have an estimated focal depth (all post-1 970). The seismicity doesn't show clusters in the area of Lake Norman.

McGuire pre-1950 post-1950 pre-impoundment 20' * <2 km o <2 km ------ - ----------- m unknown

2-5 km o 2-5 km I <2kkm

> km 0>km km " 2-5kmn 36PN I-------

r---- -------- " >5km post-impoundment

unknown M~Y " <2km

2-5km

" >5km 2a 35PN ----------- i --------

4a~ -- - i NY 82OW NY 81OW Xc 800W 16

Harris There are 16 earthquakes within 100 km of the Harris NPP of which only 2 have been instrumentally recorded: one in 1981 with a depth of 1 km and one in 1993 with a depth of 5 km.

Both are far from the Shearon-Harris Reservoir.

Haris 13 .,*..

,lrwl*l F 1 pre-impoundment 4&~ m unknown

<2km 2&

2-5km

>5kkm 36PN

-~. - post-impoundment a----

unknown

- -- - - ,- - --- - - - - - --- -- - - " <2km a

2OY --- - --- -* - - - - - - - - - *2-5km 0 >5 km qIZO - - I

"" W 79gW 78OW 77'>W 76OW 17

NPPs Located on Rivers Hatch There are 5 earthquakes within 100 km of the Hatch NPP ( earthquakes are superimposed in the figure).

Hatch 33°N 49 -------- --- --- I --------

40' .............- - ------- ------

a i

p 32ON ------- r---- - ---- ---- .......---......

I pr-1 7 pot1 7 20'- ---- r-oo~I -

tl°oIo~

- - <2- - n --

0 I-kn

2 5 r N > 5 r r 31ON 40' 20' 82o 40" 2(r 18

Vogtle There are 94 earthquakes within 100 km of the Vogtle NPP. Location of pre and post 1950 earthquakes are the same, depths are consistent.

Vogue

pre-1970 20' m ---------.--

I I

E i

. m..unknown unk......

><2kmn

2-5kmn 34°N

.. . ... .[ .. .. T ..-... . . . . . . . .*],r. . . . *>Sk in

mll* post-19g70

I -- - -- -

ut' -- - -*,*- unknown 40' .... .... . N ..... * <2k in

**2-Skin 20'

A I 33ON

, , I I 40' ----------- --------- -....... ---- - -...... - - - --- -

I 830'W 30' 82OW r 89OW 30' 80W 19

Lee There are 164 earthquakes within 100 km of the Lee NPP. Most of the seismicity pre-1978 has unknown depth (fixed at 0).

Lee 36ON 2 9 --------- . . --

a 1Bit II * ', , i pre-1 970

" i: ,,

I N unknown 4 ------------------------------

I------------

ie i * -*i O------

I <2krn 40' ------- . . .-- . -* a-I--- a a a~ a >5kmn 2Y ---- --- W --- 3-" ---- 0 80 8N~ow unknown ajP 82@W 30 Blnow0' NO 20

Brunswick There are 45 earthquakes within 100 km of the Brunswick NPP, none of them has an estimate of the focal depth. The NPP is located near the coast.

Brunswick 21

Surry There are 31 earthquakes within 100 km of the Surry NPP of which 8 (post-1 978) have an estimate of focal depth. The plant is located on the James River.

Surly 38ON 48'-

20- ------------------- ---------- I-------

40..... - ' A 2 -----

--- "- I .......

37ON ------- ------- -------.........

, U I I 40 - ..----- ---*-----

pre-1970 post-1970 m unknown

unknown 2' ------- ,. <2krn * <2km -

M 2-5kmn 02-5kmn U >5kmn I * >5kmn

36ONo 40' 20' 77ov 40' 2(0 7m0 Summary of Assessments of Additional RI Earthquakes Thirty additional RI or potentially RI earthquakes were identified in the Version 7 CEUS SSC catalog. Of these, thirteen are large enough (E[M] ? 2.9) to potentially affect recurrence calculations. Some of these were identified as dependent events of other earthquakes in the Version 7 catalog. The thirty earthquakes will be removed from an updated catalog prior to updated completeness and recurrence calculations.

22

Charleston, SC Earthquakes Near the Time of the 1886 Earthquake Sequence -

The table below lists 7 earthquakes from the Version 7 CEUS SSC catalog from the time period 1799 to 1868 in South Carolina that were identified as being potentially mislocated to areas away from Charleston.

Questioned Charleston SC Area Earthquakes from Version 7 of CEUS SSC Catalog TMPID yr Mo Dy hr mn Sec Lat Ion E[M] Source of Catalog

_________ _____ ____Location USGSnd_000145 TMP00331 1799 4 11 8 20 0 33.95 -80.18 4.68 Revised by Jeff Munsey of TVA based on Bakun and H..p .e.r .Me h d.....................

TMO1O TMO131 1860 186 1

..... ... 19 3 1 1 6 I 0 0

.0 0

i............

3. .68 3.91

-80.57

-82.02 4.

4.21 4.54 USGSnd_000427 SeebArm87_000014

....lr ~ -*... *46;....

6..............

R.ý: .....

I**

S1 -82.86 417 USGSnd000771 TMP2O9 88 1 2 5 0 3.71 -81.66 4.13 USGSnd_000805 f*"*

'i'*-**.."5 1...................]

TMP230 88 ...............

1 ..............

129.5 ................

].......................

318 ..................

-80.17 I..............

4.33 USGSnd_000860.

The majority of these earthquakes have locations and times that come from the USGS's earthquake catalog used for seismic hazard mapping. The primary source of the USGS catalog is the NCEER-91 catalog. The events in question have alternative locations in the SUSN catalog that place them at the location of the 1886 Charleston, SC main shock. We have reviewed the identification of these earthquakes and assignment of these locations in the development of the Version 7 CEUS SSC catalog in light of additional information in the paper by W.H. Bakun and M.G. Hopper (2004, "Magnitudes and Locations of the 1811-1812 New Madrid, Missouri, and the 1886 Charleston, South Carolina, Earthquakes," Bulletin of the Seismological Society of America, 94, 64-75) and recent information provided by Donald Stevenson and Dr. Predeep Talwani (written communication, February 19, 2014). The individual earthquakes are discussed below.

TMP00331, 1799/4/11. E[M1 4.68.

This earthquake was originally located at the 1886 main shock site in the source catalogs.

However, additional analysis of the reported intensity data by Jeff Munesy of TVA, which 16 includes intensity VI at Statesburg, SC and intensity V at Wilmington, NC indicates a locat on north of Charleston. The location in the Version 7 catalog was obtained by Jeff Munsey using the Bakun and Hopper method. There does not appear to be a compelling reason to move this earthquake to Charleston and the recommendation is to use the location obtained by Jeff Munsey.

23

TMP01089, 1860/1/19, E[M] 4.21.

The location in the Version 7 catalog is based on NCEER-91. Donald Stevenson and Dr.

Predeep Talwani provided the Isoseismal map shown below based on their interpretation of the available intensity data. These data clearly suggest a location near Charleson. The recommendation is to utilize the Charleston location given in the SUSN catalog.

Isoseismal map for January 19, 1860 earthquake provided by Donald Stevenson and Predeep Talwani (written communication, February 19, 2014).

TMPO1731, 1886/9/1, EEM] 4.54.

As indicated by Donald Stevenson and Predeep Talwani (written communication, February 19, 2014), TMPO1 731 appears to be a duplicate of TMPO1 732, which has a Charleston location based on their evaluation of archival data. The recommendation is to remove this earthquake from the catalog as a separate earthquake.

TMP01739, 1886/9/1, EfMI 4.17.

Donald Stevenson and Predeep Talwani (written communication, February 19, 2014) recommends that the location given in the SUSN catalog be used and the time changed to 14:45 UTC. The recommendation is based on examination of the two closest newspapers to the reported location (Abbeville Press and Banner, and the Anderson Intelligencer)that shows only references to the Charleston catastrophe, and no mention of any earthquake activity near Abbeyville or Anderson. Given this information, the record appears to be a duplicate of TMP01738, The recommendation is to remove the earthquake from the catalog as a separate earthquake.

24

TMP02019. 1886/10/22. E[Ml 4.13.

Review of the data indicates that TMP02019 is likely a duplicate of TMP02024 and that the time for event TMP02024 should be changed to 10:25 UTC. Bakun and Hopper (2004) studied this event using the intensity data from Talwani and Sharma (1999) and obtained an offshore Charleston location. Recommendation is to remove TMP02019 from the catalog and use the Charleston location in SUSN and the estimated moment magnitude given in Bakun and Hopper (2004) for TMP02024.

TMP02025, 1886/10/22, E[M] 4.13.

Bakun and Hopper (2004) studied this event using the intensity data from Talwani and Sharma (1999) and obtained an offshore Charleston location. Recommendation is to use the Charleston location in SUSN and the estimated moment magnitude given in Bakun and Hopper (2004) for TMP02025.

TMP02360,1888/1/12, EM1 4.33.

The location for this event was taken from the USGS. Donald Stevenson and Predeep Talwani (written communication, February 19, 2014) indicate that there are no newspaper reports that support a location between Sumter and Darlington (34.18 -81.17) and that the correct time should be 14:55 UTC. The event may be a duplicate with TMP39326, with a reported time of 15:54 in SUSN and a Charleston location. Recommendation is to remove TMP02360 from the catalog.

Our review turned up another potential duplicate. Bakun and Hopper (2004) also studied the Charleston aftershock on 1886/11/5 17:20 and found a location near Charleston, but slightly inland from other locations. Talwani and Sharma (1999) also concluded that this earthquake occurred at a slightly different location than other Charleston aftershocks. This earthquake appears in the Version 7 catalog as TMP02071. There is also an event TMP02072 that is listed in the USGS catalog with time 12:25 with a location to the northwest of Charleston. Both events were flagged as Charleston aftershocks in the declustering, but the timing suggests that they may be duplicates. The recommendation is to remove TMP02072 and use the magnitude and location given in Bakun and Hopper for TMP02071.

25

Development of a Version 8 Catalog The above assessments were used to create a Version 8 CEUS SSC catalog specifically for calculating earthquake recurrence rates in the southeastern US.

Revised Assignments of Parametersfor 1886 CharlestonEra Earthquakes The assessments of the six Charleston 1886 era earthquakes described above further call into question the earthquake locations provided by Seeber and Armbruster (1987). These locations 18 and size assessments were incorporated into th EER-91 catalog and then into the USGS catalog that was used as the primary source for LOJCEUS SSC Version 7 catalog. The original Seeber and Armbruster (1987) listing was also incorporated into the CEUS SSC Version 7 catalog, along with their listed values of felt area.

Seeber and Armbruster (1987) categorized the 1886 Charleston era earthquakes into 5 categories. Reexamination of Seeber and Armbruster (1987) indicated that the earthn uakes in their Category 1 and Category 2 had nominal felt areas assigned to them (100 knt.Js these were not actual felt areas assessed from the distribution of felt reports, it was judged that they should not be used to assess magnitude using the models developed in NUREG-2115 based on actual felt areas, and the values of ln(FA) were removed from the Version 8 catalog for the purpose of magnitude assessment.

The Seeber and Armbruster (1987) Category 3 earthquakes are defined as

"...(3) events apparently reported from more than one town, but which are unreliable because large populated areas between these towns did not report feeling the event ... "

The interpreted mislocated events TMP01731 and TMP01739 are listed as Category 3 in Seeber and Armbruster (1987).

Seeber and Armbruster (1987) assigned felt areas as follows:

"The felt areas assigned to events felt at less than 5 towns was the area of the circle with diameter equal to the distance between the most distant felt reports. The felt area assigned to events felt at 5 or more towns is the area of the ellipse with a major axis equal to the distance between the most distant felt reports and a minor axis twice the distance from the major axis to the furthest felt report."

The description of Category 3 events as "unreliable" and having large areas without felt reports between towns with felt reports indicates that the assigned felt areas for these events may also be unreliable. In many cases, the maximum intensity for Category 3 events is II or I1l. Figures Al, A2, A2, and A3 compare the 10 and In(FA) values for Category 3, 4, and 5 earthquakes, respectively from Seeber and Armbruster (1987) with the data from other earthquakes in the Version 3 CEUS SSC catalog. The values of In(FA) for Category 3 appear to be biased high for the assigned 10 compared to the general population. Given the evident bias and the unreliability of the events, the Seeber and Armbruster Category 3 events that are duplicated by SUSN 26

events are removed from the Version 8 catalog and for those Category 3 events that are not duplicated, the values of In(FA) are removed from the Version 8 listing for use in magnitude 1201 2

assessment. iL The comparisons for the Category 4 earthquakes on Figure A2 show general consistency in the 10-1n(FA) data with the rest of the catalog. Many of the Category 4 earthquakes have locations near Charleston. These events are left in the catalog.

The remaining question is the large number (about 25) of the Category 5 earthquakes. A number of these have SUSN entries with the same time, but often significantly different locations. Category 5 is considered by Seeber and Armbruster as the best located. Five of the interpreted mislocated earthquakes in the above list are Category 5 earthquakes, indicating that there are issues with some of these locations. In addition, the data shown of Figure A3 indicate that the assigned In(FA) may be biased high for this category. These events were examined again in comparison to other events in the catalog from SUSN. The NCEER-91 location for Where the Seeber and Armbruster error ellipses include the SUSN locations, the SUSN locations were used as the primary location. Clearly not all of these earthquakes occurred exactly in the same place, In many cases, the NCEER locations differ from the Seeber and Armbruster locations and sometimes appear to be an average of the two. The bias in the 10-In(FA) data for these events and location bias for the 6 large events initially identified further suggests that the SUSN locations be used in place of the Seeber and Armbruster / NCEER locations. For those events that could not be associated with SUSN and have very large error ellipses and 10-ln(FA) assessments that appear biased, the In(FA) data were removed from the catalog for magnitude assessment.

12 10 ------

+4 8 8W ----

40 ' 1 W

4Um E 6 4.m.u...hhh.. *Non Seeber and Armbruster (1987) assessments

4 .... Seeber and Armbruster Category 3 4

2 0 0 5 10 15 20 In(Felt Area sq kin) 27

Figure Al comparison of ln(FA)-I0 data for Category 3 Earthquakes from Seeber and Armbruster (1987) with data from other earthquakes from the CEUS SSC Version 7 catalog.

12 10 #- *.*

8 - .....

V 4J *3~

E* 6 ......

ag *Non Seeber and Armbruster (1987) assessments E 40

4 II *Seeber and Armbruster Category 4 4 -m

4 .4U.S lW 2--A-0 0 5 10 15 20 In(Felt Area sq km)

Figure A2 comparison of In(FA)-I0 data for Category 4 Earthquakes from Seeber and Armbruster (1987) with data from other earthquakes from the CEUS SSC Version 7 catalog.

28

12 1 .9-10 -#- -

8 0*

4*

06 6 *iii----; . *-*Non Seeber and Armbruster (1987) assessments E

" 4 ... ASeeber and Armbruster Category 5 4 - -* lS 2 --

0 0 5 10 15 20 In(Felt Area sq km)

Figure A3 comparison of ln(FA)-I0 data for Category 5 Earthquakes from Seeber and Armbruster (1987) with data from other earthquakes from the CEUS SSC Version 7 catalog.

After making the adjustments described above, catalog declustering was performed. As a result, the classification of nine additional earthquakes at locations distance from Charleston significant to hazard (E[M]>2.9) were changed from dependent to independent. Previously, these CýD F2 earthquakes had been classified as dependent earthquakes in clusters associated with the earthquakes identified above. The information for each of these earthquakes was reviewed, including additional information provided by Stevenson and Talwani (written communication, Feb 26, 2014). These events are discussed below.

TMP01942, 1886/9/28, ElM1 3.10.

This is a Category 4 earthquake in Seeber and Armbruster (1987) and is listed in NCEER-91. Its 10 (3) and In[FA] (8.0) are consistent with the general population of CEUS SSC earthquakes (see Figure A2). However, Stevenson and Talwani (written communication, 2014) state:

"This is one of the events listed by Seeber and Armbruster that we term to be phantom events. We can find no support or validation for the event or the location. The Union newspaper was not available for this date.

However, a check of other papers in the region (The nearest at Greenville, SC approx. 40 miles away) showed no mention of an earthquake in Union, South Carolina on September 28. The Greenville paper contained articles related to the Charleston event but no mention of anything in the upstate. We do not believe this to be a genuine event."

Recommendation, consider this to be a false event.

29

TMP02002, 1886/10/12, E[M] 3.04.

Although this event was listed as a category 4 earthquake in Seeber and Armbruster (1987), it was not carried forward into NCEER-91. Also the ln(FA) of 8.46 is anomalous compared to the 10 of II (Figure A2). The recommendation is to not use the felt area reported by Seeber and Armbruster (1987), which will result in the event not being considered in estimation of earthquake recurrence.

TMP02068, 1886/11/04, E[M] 3.18.

Although this event was listed as a category 4 earthquake in Seeber and Armbruster (1987), it was not carried forward into NCEER-91. Also the In(FA) of 8.92 is anomalous compared to the 10 of II (Figure A2). The recommendation is to not use the felt area reported by Seeber and Armbruster (1987), which will result in the event not being considered in estimation of earthquake recurrence.

TMP02134. 1886/12/08, EfM1 3.11.

This event was listed as a category 2 earthquake in Seeber and Armbruster (1987) and was not carried forward into NCEER-91. Jeff Munsey also identified the event from archival data with a similar 10 of IVN to the 10 of IV reported in Seeber and Armbruster (1987). Stevenson and Talwani (written communication, Feb 26, 2014) indicate:

"...close review of the Columbia Daily Record for the time period of 12/08/1886 to 12/13/1886 showed no reports of felt earthquakes in Columbia. We do not believe this to be genuine."

Based on this assessment, and the fact that the earthquake only potentially affects recurrence calculations because of the 10 assignment of 4.5 Munsey (2006) suggests that this earthquake be considered as either a false event or too small to include in recurrence calculations.

TMP02136. 1886/12/11. E[M] 3.25.

This is a Category 5 earthquake in Seeber and Armbruster (1987) and is listed in NCEER-91. Its 10 (4) and In[FA] (8.22) are consistent with the general population of CEUS SSC earthquakes (see Figure A3). Stevenson and Talwani (written communication, Feb 26, 2014) indicate:

"The listed location for this event plots just east of Abbeville, SC. This, may be a real event. In the December 13, 1886 edition of the Abbeville Press and Banner a short piece addressing a loud noise heard on the Saturday before (12/11) appeared.

....The Noise on Saturday: Many persons in the vicinity of Abbeville heard the noise, sound, explosion or whatever it may have been last Saturday afternoon. Mr. A.E. Lewis says it was in the air from him at an angle of 45 degrees a little south of west. Mr. T. L. Haddon says it sounded as if it was over and beyond his gin house."

From this description it is unclear if this was an earthquake or not.

Nothing is mentioned about people feeling the ground move, only about a loud sound. No mention of this event could be found in the Columbia Daily Register, Edgefield Chronicle, or Laurens Advertiser. We feel it doubtful that this is a real earthquake as all mentions above are to noises If this event were to be given the benefit of doubt and accepted as a genuine earthquake, the above, Abbeville, account would lend itself to an 30

assigned intensity considerably less than IV and should probably not be considered. "

The above description indicates that the event may be real. Classification as Category 5 earthquakes in Seeber and Armbruster (1987) indicates that the earthquake was reported in multiple towns. As there is some evidence for the earthquake, there is no clear reason to discount it, and the recommendation is to retain it in the catalog.

TMP02173, 1887/01/12, E[M] 2.91.

This is a Category 4 earthquake in Seeber and Armbruster (1987) and is listed in NCEER-91. Its 10 (3) and In[FA] (7.09) are consistent with the general population of CEUS SSC earthquakes (see Figure A2). Stevenson and Talwani (written communication, Feb 26, 2014) indicate:

"This event plots just outside Due West, SC. between Greenwood and Anderson. Checking issues of the Anderson Intelligencerand Abbeville Press and Banner through the remainder of January 1887 showed a report of a small earthquake near Due West, SC. However, it is reported to have occurred on 01/05/1887. This little event seems to have escaped all catalogers. There is nothing reported for 01/12/1887. From the Abbeville Press an Banner CHICKASAW'S CHIT CHAT; from Due West, SC Jan. 10 1887: "A very perceptible shock of earthquake was felt here last Tuesday morning. Some persons have thought that shocks have been occurring quite frequently for several weeks, but not until last week have they had the bravery to speak positively as to their occurrence."

The above description indicates that this was likely a small earthquake. However, the assessment of felt area by Seeber and Armbruster (1987) is only approximate, and places this earthquake at the edge of being included in recurrence calculations (E[M] a 2.9). The recommendation is to include this earthquake in the catalog, but consider its size to be likely smaller than E[M] 2.9.

TMP02393, 1888/04/05, EfM1 4.3.

This event was identified by Munsey (2006). Its size was assessed on the basis of an assigned intensity of VINII, which were described by Munsey (2006) as being very localized effects. The fact that the event was not reported in Seeber and Armbruster (1987) indicates that the high local effects were not widespread. Stevenson and Talwani indicate:

To our knowlege this event appears in no other catalog except the CEUS-SSC catalog. The location of the event plots just 5 miles south east from the center of Newberry, SC. In checking copies of the Newberry Herold and News for the month of April 1888 we could find no mention of an earthquake anywhere near Newberry. There was only a mention of an earthquake that apparently occurred in China. A check of the Abbevillle Press and Banner, the Edgefield Advertiser, and the News and Herald (Winnsboro,SC) for the month of April, 1888 showed no mention of any earthquakes other than the one in China also appearing in the Newberry paper."

Given that the effects identified by Munsey (2006) are very localized and other investigators did not identify effects on this date in surrounding areas indicates that if this was an earthquake, it 31

was likely small. Therefore, the recommendation is to consider this potential event to be too small to affect recurrence calculations.

TMP02423, 1888/08/15, E[M1 3.12.

This is a Category 4 earthquake in Seeber and Armbruster (1987) and is listed in NCEER-91. Its 10 (4) and In[FA] (7.55) are consistent with the general population of CEUS SSC earthquakes (see Figure A2). Stevenson and Talwani (written communication, Feb 26, 2014) indicate:

"This is, in fact a real event although the listed intensity may be a bit on the high side. It is actually kind of an interesting little read. It apparently occurred in or near Winnsboro, South Carolina Two mentions of it appeared in the Augusta Chronicle (Augusta Georgia). The first appeared in the August 17,1888 issue: "NOT AN EARTHQUAKE: It was rumored on the streets Wednesday night that an earthquake had been felt at Winnsboro, SC, but it was too late to verify the report by telegraphic advises. It turns out that the report was started by the telegraph operator there who heard a terrific roar and rumbling, accompanied by a rattling of windows and shaking of houses. He told the operators over the wires that there was an earthquake going on and then left the office in haste. A coal burning locomotive of the R & D. road was at the station and the noise was caused by the engineer putting on the blowers."

...Three days later a letter appears in the August 20 issue of the Augusta Chronicle with the headline "KNOWS WHAT A QUAKE IS The Telegraph operator at Winnsboro Has Something to Say of a Shock". "In justice to myself I must ask space in your columns to correct this: I will briefly state the facts in the case: 1 st. On August 15 th (Wednesday) a very decided earthquake shock was here at 6:25 p. m., standard time, not only by myself but by the entire population of our town. The duration of the shock was about twenty seconds, accompanied by the usual roaring noise. All the inhabitants can make affidavits to the effect, if necessary. 2 nd I asked only two operators by wire if they felt the shock, they being Ridgeway and Columbia. 3T I did not leave my office during the tremor which was very perceptible and quietly remained and noted the time. 4 t The passenger train, south had left Winnsboro about twenty minutes after the earthquake occurred, and there was no "coal burning locomotive" within 18 to 20 miles of my office. 5t I have been in the railroad service about ten years and I think this is sufficiently log to enable me to distinguish the roaring sound which accompanies an earthquake from that of a "coal burning locomotive." 6t A special dispatch announcing the earthquake was sent to the Charleston World. Our county paper also announced the occurrence. 7th I am a man of veracity, if I do say it myself, and I am not a "nervous operator."

J.H. Skinner; ticket agent and operator Upon review of the News and Herald (Winnsboro, SC) only a very short mention was found in the August 22, 1888 issue: "An earthquake shock was felt by some people on Wednesday. The shock was not generally 32

noticed." While this obviously is a genuine event it seems would seem the reported intensity might be a high.

Because the earthquake is clearly identified in the above reporting, the recommendation is to retain it in the catalog with the reported size measures given in Seeber and Armbruster (1987).

The following table summarizes the assessments of the larger events in the Version 7 catalog that are located at sufficient distance from Charleston to not be identified as aftershocks of the 1886/09/01 main shock. - 41 Revised Locations and Uniform Magnitudes for Specific Earth uakes Near Charleston, SC TMPID yr Mo Dy Hr Mn sec lat Ion Basis of Revised Magnitude TMP01089 1860 1 19 23 0 0 33.68 -80.57 Move to Charleston and base E[M] on 10 Event removed from catalog as a duplicate of TMP01 732.

Location and magnitude of TMP01732 do not require modification Event removed from catalog TMP01739 1886 9 1 14* 45 0 34.04 -82.9 as a duplicate of TMP01738.

Location and magnitude of TMPO1 738 do not require modification 16 9 28 3 0 0 34.7 -81.62 Consider as a false event TMP2002 1886 10 12 11 0 0 34.14 -81.33 Not use reported felt area, event becomes < E[M] 2.9 TMP02019 1886 10 22 5 0 0 34.71 -81.66 Event removed from catalog as a duplicate of TMP02023 TMP02023 -80 Magnitude taken from Bakun and Hopper (2004)

TMP02024 18 0 22 1 2 33 6 -81 Event removed from catalog as a duplicate of TMP02023 Location moved to TMP02025 1886 10 22 14 45 0 33.87 -81.01 Charleston, magnitude taken from Bakun and Hopper (2004)

TMP02068 1886 11 5 5 0 0 33.3 -82.49 Not use reported felt area, event becomes < E[M] 2.9 TMP27111 5 17 20 0 32.9 -80 Magnitude taken from Bakun and Hopper (2004)

TMP02072 1886 11 5 12 25 33.4 -80.42 Event removed from catalog as a duplicate of TMP02071.

TMP02134 -80.886 Revise 10 from 4.5 to 4 TMP02136 -8206 ain as is TMP02173... IRetain as less than E[M] 2.9, TMP02 1887 1 12 11 0 0 34.35 -82.42 remove felt area 33

TMPID yr Mo Dy Hr Mn sec lat Ion Basis of Revised Magnitude TMP02210 1887 3 4 10 0 0 33.74 -81.5 Not use reported felt area, event becomes < E[M] 2.9 TMP02360 1888 1 12 9 55 0 34.18 -80.17 Event removed from catalog as a duplicate of TM P39326.

TMP02393 1888 4 5 0 Tless0 0 34.21 -81.534 Retain, reduce to 10 4, E[M]

than 2.9 TMP02423 1888 8 151.130 0 34.37 -81.08 Retain as is

"an" n i 'o r ........ ........ ...................

.Changeiinahour The review described above indicates that their remains considerable uncertainty about the parameters of the 1886 Charleston earthquake aftershocks in the published literature. It is suggested that efforts be considered to support publishing the compilation of data on these earthquakes being developed by Don Stevenson and Dr. Pradeep Talwani to aid in further assessments of the earthquakes of this time period.

CatalogProcessing After revising the parameters of the Charleston aftershocks and removal of the RIS earthquakes, the updated catalog was processed in the same manner as the Version 7 catalog.

Magnitudes based on 10 and In(FA) of the Charleston aftershocks were recalculated using the updated metadata. These calculations were performed using the Version 7 set of relationships and 10-M and ln(FA)-M data in order to produce the same conversions as the Version 7 catalog.

This was because some of the RIS earthquakes contributed to the conversions and their removal would produce slight differences in the calculated values.

After developing the updated E[M] catalog, it was declustered using the same procedure.

Because the declustering program uses random number generation as part of the selection of which earthquakes to flag as dependent, the updated declustered catalog was edited to utilize the same set of independent and dependent earthquakes as Version 7 in areas not affected by the catalog updates in order to not introduce small differences in completeness due to this statistical fluctuation.

Completeness was then calculated for the entire region. The primary completeness regions affected were 5 and 12. The differences in completeness are generally less than 5 percent.

34

COMMENTS OF NUREG-2115 EARTHQUAKE CATALOG EComment Number Page Number Comment 1 3 insert space here between references.

I suggest that you refer to specific tables here.

e.g.,

2 3 Tables X though Y show all the earthquakes that are reported with a date and occasionally magnitude in the references above.

Table x contains earthquakes identified as RIS that are too small to be included in the CEUS SSC version 7 catalog 3 3 TABLE 1 4 3 TABLE 2 This event made is in my master file of RIS events. It is 2 miles west of the Oconee NPP. Ifyou feel the reference is compelling, I wont argue, but the epicenter is right at the shoreline of Lake Keowee.

6 4 Maybe a TABLE 3 to include the Potential Additional RIS events.

7 5 This one is in my master file of RIS events. Somehow it never made it into the SEUSSN Bulletins.

8 5 This one is also in my master file of RIS. It should have been in the SEUSSN Bulletin.

9 6 TABLE 4 ?

10 7 figure numbers with captions below figure would seem useful here.

11 8 TABLE ?

12 9 Figure numbers, captions would help, here and in the following.

13 12 The text is not clear here about what is being discussed. What is W1 MR10 W2, etc.?

You dont include North Anna in this group. Lake Anna does not appear to have generated much ifany RIS seismicity, 14 22 which is curious given the proximity to the CVSZ. Since 2011, there have been a few events near the Lake, but the filling of the reservoir did not seem to generate much if anything.

15 23 This section needs bibliography for the citations.

16 23 reference for Munsey?

17 25 reference for Bakun and Hopper, Talwani and Sharma (1999) 18 26 Reference for Seeber and Armbruster (1987).

This is an important point. The Seeber and Armbruster/NCEER work and catalog has some serious issues, and I am in complete agreement with what you are doing here to try and straighten these problems out.

20 27 good.

Amec Foster Wheeler X:\18000s\180180\3000_REPORTS TO CLIENT\CEUS_SSC_CatalogUpdate_042315\Attachment_2\Comments to Chapman PDF.docx Page 1 of 2

COMMENTS OF NUREG-2115 EARTHQUAKE CATALOG Comment Page Number I Number Comment 21 27 Something is missing here. Paragraph should be re-written.

21 29 Not clear, distant from Charleston?

23 31 Need to have bibliography with this in it.

24 33 TABLE XX W

Abbreviation

= Number to reference on spreadsheet to reveal the comment Amec Foster Wheeler Page 2 of 2 X:\18000s\180180\3000_REPORTS TO CLIENT\CEUSSSCCatalogUpdate_042315ýAttachment_2\Comments to Chapman PDF.docx

"*%RIZZO 500 Penn Center Boulevard Pittsburgh, PA 15235, USA Phone: (412) 856-9700 Fax: (412) 856-9749 www.rizzoassoc.com April 16, 2015 Project No.: 15-5403 Dr. Robert Youngs via email: Bob.Youngsuamecfw.com AMEC Foster Wheeler Environment & Infrastructure Oakland, California REVIEW OF REVISED EARTHQUAKE CATALOG FOR THE CENTRAL AND EASTERN UNITED STATES

Dear Dr. Youngs:

In accordance with Amec Foster Wheeler (AMEC) Work Order and Purchase Order (PO) No.

CO 12206224, 1 have reviewed the Memo from Robert Youngs (AMEC) to John Richards (EPRI) on the subject "Review ofNUREG-2115 Earthquake catalog with regard to identification of additional Reservoir Induced Seismicity (RIS) earthquakes in the southeastern United States and locations of earthquakes in South Carolina near the time of the 1886 Charleston, SC earthquake sequence." The results of my review are attached.

If you have any questions regarding the review, please contact me at Richard.Ouittmeyer(rizzoassoc.com or 1-412-825-2117.

Respectfully submitted, RIZZO Associates

_ Richard C. Quittmeyer, Vice

)C.(President-Seismology, RIZZO Associates Richard C. Quittmeyer, Ph.D.

Vice President - Seismology RCQ/sdr Attachment L01 155403/15

ATTACHMENT REVIEW OF REVISED EARTHQUAKE CATALOG FOR THE CENTRAL AND EASTERN UNITED STATES LOI 155403/15

REVIEW OF REVISED EARTHQUAKE CATALOG FOR THE CENTRAL AND EASTERN UNITED STATES INTRODUCTION This review addresses revisions made to Version 7 of the Central and Eastern United States (CEUS) earthquake catalog published in "Central and Eastern United States Seismic Source Characterization for Nuclear Facilities" (Electric Power Research Institute [EPRI]/ U.S.

Department of Energy [DOE]/U.S. Nuclear Regulatory Commission [NRC], 2012). Revisions were made to address two issues:

Identification of additional reservoir induced seismicity (RIS) earthquakes in the southeastern US.

Locations of earthquakes in South Carolina near the time of the 1886 Charleston earthquake.

Materials provided to review consist of:

A memorandum from Robert Youngs (AMEC) to John Richards (EPRI) that describes the changes to the catalog and their basis (Youngs, 2015).

Two emails from Donald Stevenson (Savannah River Site) to Robert Youngs (AMEC) regarding evaluation of earthquake locations in South Carolina near the time of the 1886 Charleston, South Carolina earthquake (Stevenson, 2015a, 2015b).

BACKGROUND The CEUS earthquake catalog (Version 7) was developed as part of a Senior Seismic Hazard Analysis Committee (SSHAC) Level 3 study to carry out an updated seismic source characterization (SSC) for the CEUS (EPRI/DOE/NRC, 2012). Three goals were identified for the catalog development:

1. Completeness - Include earthquakes relevant to seismic source characterization from available sources. The compilation process was based on previous compilations and seismic network bulletins and attempted to trace back information to the original source.

Attachment - Review of Revised Page 1 of 10 Earthquake Catalog for the CEUS r 155403/15 (April 16, 2015) 1*

The compilation also included special studies of individual earthquakes, earthquake sequences, and regional or topical assessments. Duplicate earthquakes and nontectonic earthquakes were flagged and not included in the final catalog used for SSC.

2. Uniformity of Earthquake Size Measure - Various estimates of size (intensity, magnitude using different scales) were compiled for each earthquake based on available information and used to determine a moment magnitude (M) value, taking into account uncertainty in magnitude estimation.

3. Catalog Review - To increase confidence in the developed catalog, it was submitted to an extensive review process by seismologists with knowledge and experience in catalog compilation. The reviewers recommended that original sources should be used, that magnitude determinations be scrutinized to discriminate use of different approaches and different manners of implementing the same approach, and that identified nontectonic events be compiled in a separate catalog. In addition the reviewers in some cases provided additional information on specific earthquakes.

Of relevance to the current revision and review, regional catalogs from the South Carolina Seismic Network (SCSN) and Southeastern United States Seismic Network (SEUSSN) were included in the compilation. Also, Dr. Pradeep Talwani from the University of South Carolina and Dr. Donald Stevenson from Savannah River Nuclear Solutions both participated in the catalog review that ultimately led to Version 7 of the CEUS catalog.

As the product of a SSHAC Level 3 process, it is expected that the CEUS earthquake catalog (Version 7, EPRI/DOE/NRC, 2012) is of high quality. As new information becomes available, however, it is necessary to evaluate the impacts and make revisions as necessary. In keeping with the SSHAC process, changes in the catalog should be based on technically defensible information, be justified, and be well documented, including their basis. This review of the current revisions focuses on those criteria.

REVIEW REVIEW OF ADDITIONAL RIS EARTHQUAKES In the CEUS SSC (EPRI/DOE/NRC, 2012) earthquake catalog, nontectonic events, including reservoir induced seismicity (RIS) earthquakes, are flagged and not included in analyses supporting SSC. Youngs (2015) indicates that, for the southeastern US, bulletins of the SEUSSN were the primary source to identify RIS events. For the current catalog revision, Attachment - Review of Revised Page 2 of 10 Earthquake Catalog for the CEUS 155403/15 (April 16, 2015) '% ;

Youngs (2015) identifies 13 additional references that were evaluated to identify additional RIS or possible RIS earthquakes. This evaluation identified:

RIS earthquakes not compiled in the raw published CEUS SSC catalog (EPRI/DOE/NRC, 2012)

" RIS earthquakes in the published CEUS SSC catalog and already flagged as RIS events

RIS and possible RIS earthquakes in the published CEUS SSC catalog, but not flagged as RIS events In addition, seismicity within 100 km of nuclear power plants (NPPs) in the southeastern US located near water bodies (e.g., lakes, reservoirs, rivers), was plotted and examined.

Comments on the evaluation of RIS earthquakes are listed in Table 1.

TABLE 1 COMMENTS ON THE EVAULATION OF RIS EARTHQUAKES COMMENT REFERENCE NUMBER DESCRIPTION In general, the conclusions regarding RIS status need to be better justified and documented. As a first step, criteria should be defined for determining if an earthquake is reservoir induced or not. Criteria might include:

Section "Additional I S Determined to be RIS by an investigator with a RIS Earthquakes" reasonable, documented technical basis

" Spatial proximity to a reservoir and shallow focal depth

" Temporal relation to reservoir filling or variations in level Clarify the use of the terms "non-RIS," "possible RIS,"

"potential RIS," and "RIS" with respect to the use of Section "Additional "probable nontectonic" and "nontectonic" in the CEUS 2 RIS Earthquakes" SSC report (EPRI/DOE/NRC, 2012). It is noted, however, that the list of nontectonic types in the CEUS SSC master catalog does not include "probable reservoir-induced."

Does this need to be added?

Attachment - Review of Revised Page 3 of 10 Earthquake Catalog for the CEUS 155403/15 (April 16, 2015)

TABLE 1 COMMENTS ON THE EVAULATION OF RIS EARTHQUAKES (CONTINUED)

COMMENT REFERENCE DESCRIPTION NUMBER While it states at the beginning of this section that the 13 references contain the additional material used to identify Section "Additional potential RIS events, at the bottom of page 5 it is noted that 3 Seto "additionale/ the review also included SEUSSN Bulletins for 1979 and References" 1980, and other events in the catalog near (spatially and temporally?) RIS events. The complete scope of the review should be clarified at the beginning of the discussion.

Section "Additional For Reference [3], the report number (Technical Report 4 RIS Earthquakes/ GL-90-1 1) could be added for better traceability.

References" Section "Additional For Reference [5], the correct Issue is 3, not 2.

5 RIS Earthquakes/

References" Section "Additional For earthquakes identified as RIS that are not in the CEUS 6 RIS Earthquakes/ SSC catalog, clarify if they will be added to the CEUS SSC Review Results" catalog of nontectonic events.

Use consistent criteria to evaluate earthquakes. For example, TMP14740 is judged to be a non-RIS earthquake because Reference [1] noted there was no correlation between the onset of seismicity and reservoir level; but 7 RIS Earthquakes/ TMP07159 is judged to be a potential RIS earthquake 7Rei EaRthqkesls because its preferred location coincides with the location of other earthquakes judged to be RIS. TMP 14740 also coincides with the location of other events judged to be RIS, but a different criterion is used (correlation to reservoir water level) in assessing that event.

TMP07012: The discussion notes that the earthquake Section "Additional could possibly be a RI event, but the conclusion is to retain 8 ISe "addtionales it as a non-RIS earthquake. Elsewhere (e.g., TMP09000) 8Rei EaRthqkesls events of uncertain RIS origin are identified as a "possible RI earthquake." Clarify the basis and implications for the "possible" classification.

Section "Additional TMP07159: Correct the spelling of "Bulltins."

9 RIS Earthquakes/

Review Results" Attacbment - Review of Revised Page 4 of 10 Earthquake Catalog for the CEUS 155403/15 (April 16, 2015)

TABLE 1 COMMENTS ON THE EVAULATION OF RIS EARTHQUAKES (CONTINUED)

COMMENT REFERENCE DESCRIPTION NUMBER TMP07565: Clarify what criteria are used to reach the conclusion (excellent correlation with water fluctuations, Section "Additional but poor spatial and temporal proximity). Also, the discussion notes that the earthquake is mentioned in 10 RIS Earthquakes! Reference [ 11 ], which cites Talwani (1976, "Earthquakes associated with the Clark Hill Reservoir, South Carolina--

A case of induced seismicity"), the title of which suggests the event is induced.

TMP08078: Document the basis for the RIS conclusion.

Section "Additional Current discussion suggests it is because a monitoring program was established after it occurred. Also, note that 11 RIS Earthquakes/ this event and TMP07565 are discussed in the same section of Reference [ 11], but different RIS conclusions are reached for the two events.

TMP08787: If possible, clarify what water level is being Section "Additional measured in the well. It appears this earthquake is located at Lake Jocassee; how does the lake level correspond to the 1Rei EaRtheslts" water level in the well? Also, in the last sentence of the discussion, "smaller that earthquakes" should be "smaller than earthquakes."

Section "Additional TMP08971: It is not clear how the information presented 13 RIS Earthquakes/ leads to the conclusion that the earthquake is reservoir-Review Results" induced. Location and depth?

TMP09000: Note that the date given for this event appears Section "Additional to be incorrect. In the CEUS SSC report, TMP09000 has a 14 RIS Earthquakes/ date of 2/11/1978. This evaluation implies that Review Results" classification of "possible RIS event" derives from a "location and depth" criterion.

Section "Additional TMP09355: In the first sentence "dependent even" should 16 RIS Earthquakes/ be "dependent event."

Review Results" Section "Additional TMP10034: Clarify if Reference [2] identifies the event as 17 RIS Earthquakes/ reservoir-induced or simply lists it.

Review Results" TMP10034 and TMP10104: Clarify if there is a difference between being "flagged" and "listed" in the SEUSSN Sectio "adtionales/ Bulletin. For example, does "flagged" imply identification 1Rei EaRtheslts" as a RIS event? Does "listed" simply mean "included" or does it also carry the meaning of being identified as a RIS event?

Section "Additional Bottom of Page 5: Should "references [1] through [5]" be 19 RIS Earthquakes/ "[1] through [13]"? If not, explain how the following list Review Results" differs from the review discussed above.

i - a a ______________________________________________- d Attachment - Review of Revised Page 5 of 10 Earthquake Catalog for the CEUS 155403/15 (April 16, 2015)

TABLE 1 COMMENTS ON THE EVAULATION OF RIS EARTHQUAKES (CONTINUED)

COMMENT COMMEN REFERENCE DESCRIPTION NUMBER Page 6, Table: For many earthquakes in this table there has been no specific or general discussion of the criteria and Section "Additional basis for determining they are "RIS" or "possible RIS."

20 RIS Earthquakes/ Because this review is modifying a product developed as Review Results" part of a SSHAC Level 3 SSC study, the basis for making changes to the catalog should be clearly and completely documented.

Page 7, Figure: Clarify what is meant by "affected by these RIS earthquakes." Is the focus on recurrence Section "Additional parameters? Are all earthquakes in the list shown, or only 21 RIS Earthquakes/ those that would be included in recurrence calculation? At Review Results" what distance from a site does the impact of changes to the catalog on calculation of recurrence parameters become negligible?

While plots of earthquakes are shown relative to NPP Section "Additional locations and lakes/rivers, there is no summary for each RIS Earthquakes/ NPP, or in general, whether this comparison identified any Seismicity within 100 additional RIS or possible RIS earthquakes. Consider km of NPPs" providing at least a general summary of the conclusions of this comparison.

Consider providing a summary figure that shows the seismicity from the CEUS SSC catalog Version 7 for the SEUS and identifies (e.g., filled versus open symbols) the Section "Additional 30 events now being moved to the nontectonic events 23 RIS Earthquakes/ catalog. It would also be useful to discriminate those Summary" newly classified RIS events that have E[M] of 2.9 or greater and thus would impact recurrence calculations.

Multiple figures might be needed to show the information at a useful scale.

Attachment - Review of Revised Page 6 of 10 Earthquake Catalog for the CEUS 155403/15 (April 16, 2015)

REVIEW OF CHARLESTON, SC EARTHQUAKES NEAR THE TIME OF THE 1886 EARTHQUAKE SEQUENCE Youngs (2015) reviews available data relevant to evaluation of the catalog parameters for seven earthquakes in the South Carolina region that are suspected of being mislocated. Two of the earthquakes occurred prior to the 1886 mainshock (in 1799 and 1860), four occurred in 1886, and one in 1888. Reevaluations are based largely on ongoing, unpublished evaluations by Dr.

Donald Stevenson and Dr. Pradeep Talwani (Stevenson, 2015a, 2015b) of archival material from newspapers in South Carolina and adjacent regions. These evaluations update those made based on more limited archival data by Seeber and Armbruster in the 1980s (e.g., Seeber and Armbruster, 1981, 1987) and those incorporated in the EPRI-SOG and NCEER-91 catalogs that evolved into the USGS catalog.

Although the technical bases for the locations in the CEUS SSC Version 7 catalog are not compared to those of Stevenson and Talwani (and may not be readily available), the data described and reasoning used by Stevenson and Talwani support the conclusions Stevenson and Talwani reach. The updates in location and the identifications of duplicate or false events are supported by the available information.

REVIEW OF DEVELOPMENT OF VERSION 8 CATALOG In preparing Version 8 of the CEUS SSC catalog to incorporate identified revisions, the overall results of Seeber and Armbruster (1987) were reconsidered, especially with respect to the appropriateness of their estimates of felt area used for E[M] estimation. Reexamination of the felt areas determined by Seeber and Armbruster (1987) clarified that the basis for some was a nominal assumption of 100 km 2 ; for others comparison to larger datasets relating felt area and maximum intensity suggest the methodology used by Seeber and Armbruster (1987) can be biased. Based on the information and analyses documented in Youngs (2015), the elimination of some Seeber and Armbruster (1987) felt areas from the Version 8 CEUS SSC catalog is reasonable and justified.

The recommendation that support be provided for the publication of the assessments of Stevenson and Talwani is endorsed. Publication would make these assessments more transparent and readily available to the seismological community. Pending such publication, it is recommended that the emails from Dr. Stevenson be included as attachments to Youngs (2015) to enhance the traceability and transparency of the assessments.

Attachment - Review of Revised Page 7 of 10 Earthquake Catalog for the CEUS 155403/15 (April 16, 2015) F"

Processing of the catalog following reevaluation of RIS events and events related to the 1886 Charleston sequence is reasonable and straightforward.

Specific comments on this section of Youngs (2015) are contained in Table 2.

TABLE 2 COMMENTS ON DEVELOPMENT OF VERSION 8 CATALOG COMMENT REFERENCE DESCRIPTION NUMBER First sentence: The previous section states that seven Section "Development earthquakes are identified as possibly mislocated. Here of a Version 8 Catalog"/ the assessments of six earthquakes are mentioned.

"Revised Assignments Seven were assessed, but one was not changed. This of Parameters" apparent difference (seven versus six) should be clarified to avoid confusion.

First sentence: The sentence indicates that the Section "Development reevaluation of six Charleston 1886.era earthquakes of a Version 8 Catalog"/ "further calls into question the earthquake locations "Revised Assignments provided by Seeber and Armbruster (1987)." Why of Parameters" "further?" This appears to assume knowledge of other assessments not documented in the current memo.

Section "Development Page 27, end of the 2nd full paragraph: A sentence 26 of a Version 8 Catalog"/ fragment appears at the end of the paragraph. Provide "Revised Assignments the missing portion of the sentence or delete, as of Parameters" appropriate.

Section "Development The SUSN catalog locations are often preferred over the of a Version 8 Catalog"/ Seeber and Armbruster (1987) locations. If available, "Revised Assignments consider providing some discussion of the basis for the of Parameters" SUSN locations for pre-instrumental locations.

TMP02134: For this event the conclusion mentions two options: false event or too small to include in recurrence relations. Clarify how the event was treated in the Version 8 catalog. That is, was it deleted from the Section "Development earthquake catalog and added to the nontectonic list as a 28 of a Version 8 Catalog"! false event, or was it included with a E[M] less than 2.9.

"Revised Assignments The following table suggests it was retained.

of Parameters" Also, can it be clarified if Stevenson and Talwani considered the archival data that Munsey used to identify the event?

Attachment - Review of Revised Page 8 of 10 Earthquake Catalog for the CEUS 155403/15 (April 16, 2015)

TABLE 2 COMMENTS ON DEVELOPMENT OF VERSION 8 CATALOG (CONTINUED)

NUMER REFERENCE NUMBER DESCRIPTION Section "Development TMP02173: For this earthquake the conclusion of a Version 8 Catalog"/ indicates that it is likely smaller than E[M] 2.9. Clarify 29 g how this conclusion is implemented in the catalog.

"Revised Assignments What E[M] is assigned in the Version 8 catalog for this of Parameters" Iearthquake (e.g., 2.8, something else)?

SUMMARY

As new information becomes available, it is appropriate to revise the evaluation of seismic events included in CEUS SSC earthquake catalog (Version 7). Because the Version 7 catalog represents a product developed as part of a SSHAC Level 3 study, it is important that revisions to the catalog have an appropriate technical basis, be justified, and be well documented. The comments provided here on the Youngs (2015) memo are provided with that goal in mind and to enhance the confidence in the Version 8 catalog.

Attachment - Review of Revised Page 9 of 10 Earthquake Catalog for the CEUS 155403/15 (April 16, 2015)

'Ii

REFERENCES Electric Power Research Institute/U.S. Department of Energy/U.S. Nuclear Regulatory Commission (EPRI/DOE/NRC), 2012, "Central and Eastern United States Seismic Source Characterization of Nuclear Facilities," EPRI Report # 1021097, DOE Report # DOE/NE-0 140, NRC NUREG-2115,Palo Alto, CA (EPRI), Washington, D.C. (DOE, NRC), 2012.

Seeber, L., and J. G. Armbruster, 1981, "The 1886 Charleston, South Carolina Earthquake and the Appalachian Detachment," Journal of Geophysical Research, Vol. 86, No. B9, pages 7874-7894, 1981.

Seeber, L., and J.G. Armbruster, 1987, "The 1886-1889 Aftershocks of the Charleston, South Carolina Earthquake: A Widespread Burst of Seismicity," Journal of Geophysical Research, Vol. 92, No. B3, pages 2663-2696, 1987.

Stevenson, D., 2015a, Email from Donald Stevenson (SRS) to Robert Youngs (AMEC) with the

Subject:

"Re: South Carolina earthquakes," February 19, 2014 (with attached Microsoft Excel file CharlestonareaEqs.xlsx), 2015.

Stevenson, D., 2015b, Email from Donald Stevenson (SRS) to Robert Youngs (AMEC) with the

Subject:

"Re: South Carolina earthquakes," February 26, 2014 (with attached Microsoft Excel file AdditionalCharlestonareaEqs.xlsx), 2015.

Youngs, R., 2015, Memorandum from Robert Youngs (AMEC) to John Richards (EPRI) with the

Subject:

"Review ofNUREG-2115 Earthquake catalog with regard to identification of additional Reservoir Induced Seismicity (RIS) earthquakes in the southeastern United States and locations of earthquakes in South Carolina near the time of the 1886 Charleston, SC earthquake sequence," March 5, 2014.

Attachment - Review of Revised Page 10 of 10 Earthquake Catalog for the CEUS 155403/15 (April 16, 2015)

amec foster wheeler ATTACHMENT 3 Amec Foster Wheeler's Responses to Review Comments

April 23, 2015 amec d foster

Subject:

RESPONSE TO COMMENTS BY DR. MARTIN CHAPMAN wheeler All editorial comments have been accepted, and the suggested modifications have been made to the text. A revised version of the document is attached to this letter.

Discussion of the North Anna NPP is not included because the revision is limited to plants in the Southeastern U.S. As noted, Lake Anna has not produced RIS, so its exclusion has no impact on our analysis.

Of the potential 6 discrepancies noted in the review letter, only one (event dated 12/11/1986) has E[M] large enough (3.16) to be included in the recurrence calculation. Although we agree that all six earthquakes should be marked as RIS in future releases of the catalog, we conclude that the exclusion of that one earthquake from the recurrence calculation will have negligible impact on the recurrence rates, and a re-analysis is not necessary at this time.

As a general comment, we note that it would be helpful for future efforts to have a publicly available list of RIS. Currently, the SEUSSN Bulletins are not consistent in the identification of RIS: in some cases the earthquakes are clearly labeled as "reservoir induced" in other cases they are not. For example the event discussed above (12/11/1986) is only listed by its location "Lake Keowee", but it is not called out as reservoir induced.

Amec Foster Wheeler Environment & Infrastructure, Inc.

180 Grand Avenue, Suite 1100 Oakland, California 94612-3066 USA Tel (510) 663-4100 Fax (510) 663-4141 amecfw.com

RESPONSE TO COMMENTS BY DR. RICHARD QUITTMEYER Comment Reference Description Response Number In general, the conclusions regarding RIS status need to be better justified and documented. As a first step, criteria should be defined for determining ifan earthquake is reservoir induced or not. Criteria Section might include:

"Additional RIS Revised text.

Earthquakes" Determined to be RIS by an investigator with a reasonable, documented technical basis Spatial proximity to a reservoir and shallow focal depth Temporal relation to reservoir filling or variations in level Clarify the use of the terms "non-RIS,"

"possible RIS," "potential RIS," and "RIS" with respect to the use of "probable nontectonic" and Section "nontectonic" in the CEUS SSC report 2 "Additional RIS (EPRI/DOE/NRC, 2012). It is noted, Corrected nomenclature for consistency.

Earthquakes" however, that the list of nontectonic types in the CEUS SSC master catalog does not include "probable reservoir-induced." Does this need to be added?

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RESPONSE TO COMMENTS BY DR. RICHARD QUITTMEYER Comment Reference Description Response Number While it states at the beginning of this section that the 13 references contain the additional material used to identify potential RIS events, at the bottom of Section page 5 it is noted that the review also Text revised to clarify that the SEUSSN Bulletin were "Additional RIS included SEUSSN Bulletins for 1979 3 "the sole source of RIS in the southeastern US used in Earthquakes/ and 1980, and other events in the Rev 7 of the catalog.

References" catalog near (spatially and temporally?) RIS events. The complete scope of the review should be clarified at the beginning of the discussion.

Section "itiona R For Reference [3], the report number 4EArdithuales (Technical Report GL-90-1 1) could be Added.

Earthquakes/ added for better traceability.

References" Section "Additional RIS For Reference [5], the correct Issue is Corrected.

Earthquakes/ 3, not 2.

References" Section For earthquakes identified as RIS that "Additional RIS are not in the CEUS SSC catalog, They should in future releases of the Catalog. A new 6Earthquakes/ clarify if they will be added to the issue of the non-tectonic events list is beyond the Review Results" CEUS SSC catalog of nontectonic scopes of this project.

events.

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RESPONSE TO COMMENTS BY DR. RICHARD QUITTMEYER Comment Reference Description Response Number Use consistent criteria to evaluate earthquakes. For example, TMP14740 is judged to be a non-RIS earthquake because Reference [1]

noted there was no correlation Ref [1] does not consider TMP14740 as RI, and the between the onset of seismicity and SEUSSN Bulletin does not flag this event as RI either.

Section reservoir level; but TMP07159 is 7 "Additional RIS judged to be a potential RIS Dr Martin Chapman considers this event to be RI, see Earthquakes/ earthquake because its preferred discussion at the end of Part 1.

Review Results" location coincides with the location of other earthquakes judged to be RIS.

TMP14740 also coincides with the location of other events judged to be RIS, but a different criterion is used (correlation to reservoir water level) in assessing that event.

For TMP07012, the discussion notes that the earthquake could possibly be Section a RI event, but the conclusion is to The difference is that the location of TMP07012 is 8 "Additional RIS retain it as a non-RIS earthquakee based on "meager" data (Ref. [5]). Since the event is Earthquakes / of uncertain RIS origin are identified poorly located it could have happened somewhere else Review Results" and not be RI.

as a "possible RI earthquake." Clarify the basis and implications for the "possible" classification.

Section 9 "Additional RIS In the discussion for TMP07159, Corrected.

Earthquakes/ correct the spelling of "Bulltins."

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RESPONSE TO COMMENTS BY DR. RICHARD QUITTMEYER Comment Reference Description Response Number For TMP07565, clarify what criteria are used to reach conclusion (excellent correlation with water fluctuations, but poor spatial and Revised text for clarity. The same author (Talwani) first

'Additional R temdis ionl noxte tAt. the eseems to believe that the event is RI (as referenced in 10 "Additional RIS discussion notes that the earthquake [11]), then in a subsequent paper (Ref [3]) determines Earthquakes/ is mentioned in Reference [11], which that the induced nature of the earthquake is Review Results" cites Talwani (1976, "Earthquakes questionable.

associated with the Clark Hill Reservoir, South Carolina--A case of induced seismicity"), the title of which suggests the event is induced.

For TMP08078, document the basis for the RIS conclusion. Current Section discussion suggests it is because a "Additional RIS monitoring program was established Revised text.

11Earthquakes/ after it occurred. Also, note that this Earthquaesu event and TMP07565 are discussed See also response to comment 10.

in the same section of Reference [11],

but different RIS conclusions are reached for the two events.

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RESPONSE TO COMMENTS BY DR. RICHARD QUITTMEYER Comment Reference Description Response Number For TMP08787, clarify what water Revised text based on information available in Ref [2].

level is being measured in the well. It appears this earthquake is located at Section Lake Jocassee; No information given in Ref [2].

12 'Additional RIS how does the lake level correspond to Earthquakes the water level in the well?

Review Results" Corrected.

Also, in the last sentence of the discussion, "smaller that earthquakes" should be "smaller than earthquakes."

Section TMP08971: It is not clear how the "Additional RIS information presented leads to the 13 Earthquakes/ conclusion that the earthquake is Revised text.

Review Results" reservoir-induced. Location and dph depth?

TMP09000: Note that the date given Section for this event appears to be incorrect.

In the CEUS SSC report, RMP09000 14 "adtionalRs has a date of 2/11/1978. This Corrected.

Earthquakes! evaluation implies that classification of "possible RIS event" derives from a "location and depth" criterion.

Section TMP09355: In the first sentence "Additional RIS 16 Earthquakes/ "dependent even" should be Corrected.

Review Results" "dependent event."

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RESPONSE TO COMMENTS BY DR. RICHARD QUITTMEYER Comment Reference Description Response Number Section TMP10034: Clarify if Reference [2]

17 "Additional RIS identifies the event as reservoir- Clarified.

Earthquakes/ induced or simply lists it.

Review Results" TMP10034 and TMP10104: Clarify if there is a difference between being Section "flagged" and "listed" in the SEUSSN 18 "Additional RIS Bulletin. For example, does "flagged" Clarified.

Earthquakes/ imply identification as a RIS event?

Review Results" Does "listed" simply mean "included" or does it also carry the meaning of being identified as a RIS event?

Section Bottom of Page 5: Should "Additional RIS 9 '"references [1] through [5]" be "[1]

19 Earthquakes/ through [13]"? If not, explain how the Corrected.

Review Results" following list differs from the review discussed above.

Page 6, Table: For many earthquakes in this table there has been no specific or general discussion Section of the criteria and basis for "Additional RIS determining they are "RIS" or 20 Earthquakes/ "possible RIS." Because this review Revised text.

Review Results" is modifying a product developed as part of a SSHAC Level 3 SSC study, the basis for making changes to the catalog should be clearly and completely documented.

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RESPONSE TO COMMENTS BY DR. RICHARD QUITTMEYER Commen Reference Description Response Number Page 7, Figure: Clarify what is meant by "affected by these RIS Revised text.

earthquakes."

Is the focus on recurrence Section parameters? Are all earthquakes in 21 "Additional RIS the list shown, or only those that All earthquakes in Table 4, at the scale of the figure Earthquakes/ would be included in recurrence many are superimposed.

Review Results" calculation?

At what distance from a site does the impact of changes to the catalog on calculation of recurrence parameters This is beyond the scope of the project.

become negligible?

While plots of earthquakes are shown Section relative to NPP locations and "Additional RIS "additinales/ lakes/rivers, each NPP, orthere is no summary in general, whether for this 22 Seasmicthu wi comparison identified any additional Revised summary section.

Seismicity within RIS or possible RIS earthquakes.

NPPs" Consider providing at least a general summary of the conclusions of this comparison.

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RESPONSE TO COMMENTS BY DR. RICHARD QUITTMEYER Comment Reference Description Response Number R Consider providing a summary figure that shows the seismicity from the CEUS SSC catalog Version 7 for the SEUS and identifies (e.g., filled versus open symbols) the 30 events Section now being moved to the nontectonic 23 "Additional RIS events Earthquakes/ useful tocatalog. It would discriminate alsonewly those be Added figures 16 and 17.

Summary" classified RIS events that have E[M]

of 2.9 or greater and thus would impact recurrence calculations.

Multiple figures might be needed to show the information at a useful scale.

First sentence: The previous section Section states that seven earthquakes are "Development of identified as possibly mis-located.

a Version 8 Here the assessments of six 24 Catalog"/ earthquakes are mentioned. Seven Text revised for clarity.

"Revised were assessed, but one was not Assignments of changed. This apparent difference Parameters" (seven versus six) should be clarified to avoid confusion.

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RESPONSE TO COMMENTS BY DR. RICHARD QUITTMEYER Comment Reference Description Response Number First sentence: The sentence Section indicates that the reevaluation of six "Development of Charleston 1886 era earthquakes a Version 8 "further calls into question the 25 Catalog"/ earthquake locations provided by Removed word "further".

"Revised Seeber and Armbruster (1987)." Why Assignments of "further?" This appears to assume Parameters" knowledge of other assessments not documented in the current memo.

Section "Development of Page 27, end of the 2nd full a Version 8 paragraph: A sentence fragment 26 Catalog"/ appears at the end of the paragraph. Revised.

"Revised Provide the missing portion of the Assignments of sentence or delete, as appropriate.

Parameters" Information on the SUSN catalog can be found at:

Section The SUSN catalog locations are often http://www.magma.geos.vt.edu/vtso/anonftp/catalog/cat "Development of preferred over the Seeber and alogreadme.txt a Version 8 Armbruster (1987) locations. If The catalog is a synthesis of the U.S. Geological 27 Catalog"/ available, consider providing some Survey State Seismicity Map Series (C. W., B. G.

"Revised discussion of the basis for the SUSN Reagor, and S. T. Algermissen, 1984, 'United States Assignments of locations for pre-instrumental Earthquake Data File', U. S. Geological Survey Open-Parameters" locations. File Report 84-225, 123 pp.), and the Southeastern U.

S. Seismic Network catalog for events after July 1977.

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RESPONSE TO COMMENTS BY DR. RICHARD QUITTMEYER Comment Reference Description Response Number TMP02134: For this event the conclusion mentions two options:

false event or too small to include in recurrence relations. Clarify how the The event was retained in Rev 8 of the catalog. The list event was treated in the Version 8 of non-tectonic events is not being updated at this time.

Section catalog. That is, was it deleted from "Development of the earthquake catalog and added to a Version 8 the nontectonic list as a false event, 28 Catalog"/ or was it included with a E[M] less "Revised than 2.9. The following table Assignments of suggests it was retained.

Parameters" Also, can it be clarified if Stevenson We do not have that information.

and Talwani considered the archival data that Munsey used to identify the event?

Section TMP02173: For this earthquake the "Development of conclusion indicates that it is likely a29Catalog" Version 8 smaller than E[M] 2.9. Clarify how sal thisaconcln isM]

imp.Cle diy thew The statement was incorrect. The earthquake was 29 Catalog"/ this conclusion is implemented in the maintained unmodified in Rev 8 of the catalog.

"Revised catalog. What E[M] is assigned in the Assignments of Version 8 catalog for this earthquake Parameters" (e.g., 2.8, something else)?

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amec foster wheeler ATTACHMENT 4 Concurrence letters from Dr. Martin Chapman and Dr. Richard Quittmeyer

April 17, 2015 Martin Chapman RE: Review ofNUREG-2115 earthquake catalog

Dear Bob:

I have examined your responses to my comments on the work concerning the review of the NUREG-2115 earthquake catalog with regard to identification of additional reservoir induced sesimicity (RIS) earthquakes in the southeastern United States and the locations of earthquakes in South Carolina near the time of the 1886 Charleston, SC earthquake sequence.

Your responses fully address my comments.

Sincerely, Martin Chapman

500 Penn Center Boulevard Pittsburgh, PA 15235, USA

'R IZZ O Phone: (412) 856-9700

%I ASSOCIATES Fax: (412) 856-9749 www.dzzoassoc.com April 23, 2015 Project No.: 15-5403 Dr. Robert Youngs via email: Bob.Youngs(amecfw.com Amec Foster Wheeler Environment & Infrastructure Oakland, California CONCURRENCE ON UPDATED REVISED EARTHQUAKE CATALOG FOR THE CENTRAL AND EASTERN UNITED STATES

Dear Dr. Youngs:

In accordance with Amec Foster Wheeler (AMEC) Work Order and Purchase Order (PO) No.

CO 12206224, I reviewed the Memo from Robert Youngs (AMEC) to John Richards (EPRI) on the subject "Review ofNUREG-2115 Earthquake catalog with regard to identification of additional Reservoir Induced Seismicity (RIS) earthquakes in the southeastern United States and locations of earthquakes in South Carolina near the time of the 1886 Charleston, SC earthquake sequence." Comments were provided as an attachment to a letter, addressed to you, dated April 15, 2015.

In response to my comments and those of Dr. Martin Chapman, you provided me with a revised document on April 21, 2015. I reviewed the revised document and made additional comments that were transmitted to you by email on April 22, 2015. In response to these additional comments, you provided an updated revised document for my consideration on April 23, 2015. Following review of this latest document, I find that all of my comments are satisfactorily addressed and I have no further comments.

The current document describes, and supports with sufficient technical basis and justification, revisions to the Central and Eastern United States (CEUS) Seismic Source Characterization (SSC) earthquake catalog (Revision 7). The revisions focus on the southeastern United States and reflect evaluation of additional information. The additional information pertains to reservoir-induced seismicity and the location and size of earthquakes in South Carolina that occurred generally near the time of the large 1886 Charleston earthquake. The revised CEUS SSC catalog (Revision 8) is appropriate for updated calculation of recurrence parameters for the southeastern United States.

If you have any questions regarding my review or my concurrence with the comment resolutions, please contact me at Richard.Ouittmever(rizzoassoc.com or 1-412-825-2117.

Respectfully submitted, RIZZO Associates Richard C. Quittmeyer, Vice Q.c.... President-Seismology, RIZZO Associates Richard C. Quittmeyer, Ph.D.

Vice President - Seismology RCQ/sdr L02 155403/15

v t e Letter Sequence Response to RAI
TAC:MF3689, (Approved, Closed)
Initiation Request, Request, Request, Request, Request, Request, Request, Request, Request Acceptance... Supplement Administration Questions 23 October 2014 25 November 2014 Answers 31 December 2014 20 June 2013 17 December 2014 30 April 2015 26 March 2014 28 April 2015 12 November 2014 29 April 2015 Results Approval Other: ML14093A052, ML15096A513, ML15201A008, ML15226A185, ML16034A325
MONTHYEAR2014-03-20 [Table View]

ONS-2015-055, Second Response to Request for Additional Information Dated October 23, 2014, Related to Southeastern Catalog Changes and Seismic Re-Evaluations

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Dear Mr. Richards:

1.1 REFERENCES

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Dear Don:

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Dear Don and Pradeep:

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Dear Don:

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Dear John:

Dear Dr. Youngs:

SUMMARY

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Dear Bob:

Dear Dr. Youngs:

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