ML23093A157
| ML23093A157 | |
| Person / Time | |
|---|---|
| Issue date: | 04/06/2023 |
| From: | Louise Lund NRC/RES/DE |
| To: | Eric Benner NRC/RES/DE |
| Rasool Anooshehpoor 301-415-2396 | |
| Shared Package | |
| ML23093A155 | List: |
| References | |
| RIL 2023-04 | |
| Download: ML23093A157 (3) | |
Text
UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 April 6, 2023 MEMORANDUM TO: Eric Benner, Director Division of Engineering Office of Nuclear Reactor Regulation Signed by Lund, Louise FROM: Louise Lund, Director signature:lxl on 04/06/23 Division of Engineering Office of Nuclear Regulatory Research
SUBJECT:
UPCOMING PUBLICATION OF RESEARCH INFORMATION LETTER (RIL 2023-04) PALEOLIQUEFACTION STUDIES OF THE CENTRAL VIRGINIA SEISMIC ZONE The Office of Nuclear Regulatory Research (RES) is providing the enclosed Research Information Letter (RIL) entitled Paleoliquefaction Studies of the Central Virginia Seismic Zone for your information and use. The RIL (RIL 2023-04) is available in the Agencywide Documents Access and Management System (ADAMS) with an accession number of ML23093A156. It will be published publicly within the next two weeks.
This RIL has been developed as part of RES activities to identify, interpret, and document paleoliquefaction features in the Central Virginia Seismic Zone for the purpose of reducing uncertainties in the recurrence estimates and source models for large events associated with this seismic zone.
The 2011, M 5.7, earthquake near Mineral, Virginia, the largest known earthquake to have occurred in the CVSZ, raised concerns about the earthquake potential of the seismic zone.
This paleoliquefaction study builds on previous studies that found evidence of strong ground shaking caused by moderate to large earthquakes during the Holocene (past 11.7 thousand years), extends the search for earthquake-induced liquefaction features towards the eastern, northeastern, northern, and southern margins of the CVSZ, and further defines the timing, locations, and magnitudes of past events that induced liquefaction in the region.
Analysis of the newly found features along the Appomattox, in combination with previous paleoliquefaction results, suggest that (1) historical liquefaction features along the Appomattox, James, and Pamunkey Rivers formed as result of three M 5.0-5.5 earthquakes, most likely the A.D. 1758, A.D. 1774, and A.D. 1875 events, located in close proximity to the features; and (2) the prehistorical liquefaction features along the Appomattox, Mattaponi, Pamunkey, Rivanna, and South Anna Rivers formed ~3 ka +/- 500 yr during a M 6.5-6.75 earthquake centered near Holly Grove or farther east between the Appomattox and Mattaponi Rivers.
CONTACT: Rasool Anooshehpoor, RES/DE/SGSEB (301) 415-2396
E. Benner These new findings reduce the uncertainty of the timing and location of the paleoearthquake that induced liquefaction across the region and increase the magnitude estimates by up to 0.25 magnitude unit for both the historical and paleoearthquakes. In addition, features found along the Rapidan River formed between 1830-60 yr B.P., possibly during an historical earthquake or a previously unrecognized paleoearthquake near the northern margin of the CVSZ.
A draft version of this report was shared and reviewed with staff in NRR/DEX and all their comments were addressed.
Please feel free to contact Rasool Anooshehpoor of my staff at Rasool.Anooshehpoor@nrc.gov, if you have any questions.
RES has established an online quality survey to collect feedback from user offices on the usefulness of RES products and services. This survey can be found online at the hyperlink:
RES Quality Survey. I would appreciate the responsible manager completing this short survey within the next 10 working days to present your offices views of the delivered RES product.
Please share any concerns with me or the Division of Engineering contact listed, so that they may be addressed.
ML23093A155; Memo ML23093A157 OFFICE RES/DE/SGSEB RES/DE/SGSEB RES/DE NAME AAnooshehpoor AA DSeber DS LLund LL DATE Apr 3, 2023 Apr 3, 2023 Apr 6, 2023