ML100060063
| ML100060063 | |
| Person / Time | |
|---|---|
| Site: | Diablo Canyon  |
| Issue date: | 01/05/2010 |
| From: | Pacific Gas & Electric Co |
| To: | Office of Nuclear Reactor Regulation |
| Wang, A B, NRR/DORL/LPLIV, 415-1445 | |
| References | |
| Download: ML100060063 (77) | |
Text
www.fugro.com Methods used to estimate and constrain Shoreline fault:
Lloyd Cluff & Norm Abrahamson PG&E Geosciences 2009 progress briefing January 5, 2010 Location Variations in seismicity alignment Geophysical profiling Mapping offshore wave-cut platforms Style of faulting Constraints on activity (fault slip-rate)
Length and rupture area Magnitude of potential earthquakes Ground motions Primary surface fault rupture; secondary fault deformation?
DCPP Seismic Hazard Update (2007 - 2013)
Shoreline Fault Evaluation
www.fugro.com Small faults in Southwest Boundary Zone (1990)
www.fugro.com Seismicity - October 1997 to March 2007 J. Hardebeck (USGS)
www.fugro.com Alignment of small earthquakes (M < 1 to 3.5)
Hosgri fault zone
www.fugro.com Nov 2008 Preliminary Evaluation 2008 Assumptions y Length and Width Full length of the seismicity alignment (25 km)
Depth of Seismicity of 12 km Maximum magnitude: M=6.5 y Distance offshore DCPP 1 km Results y Deterministic (84th percentile) ground motions lower than 1991 LTSP ground motion
www.fugro.com Issues Identified in 2008 Length and Width y Does Shoreline fault zone extend to Hosgri?
y How far does the Shoreline fault zone extend to the SE?
y Is the fault zone continuous over its length Fault zone may be broken into small discontinuous segments Closest distance offshore DCPP y What is the distance offshore?
Activity Rate y Appear to be low, but not well constrained
www.fugro.com Epicentral Uncertainty
www.fugro.com Seismicity Alignment Cross-Sections
www.fugro.com Point Buchon area with respect to Hardebecks (2009) microseismicity lineament Apparent segmentation Northern Central Southern N
C S
www.fugro.com 2008 aeromagnetic survey tracklines along the central California Coast Ranges
www.fugro.com 2009 USGS Marine Survey Area New New Fill In DCPP
www.fugro.com Blue = tracks of high resolution marine seismic reflection and magnetic data were collected at 800 m spacing.
Red = additional marine magnetics tracks for a net 400 m spacing (Watt et al., 2009).
Track line map of marine geophysical data collected in 2008 and 2009.
www.fugro.com Boundaries of 2009 helicopter magnetic survey flown with 150 m line spacing at a nominal altitude of 100 m.
Onshore and Offshore Magnetic Integration Survey
www.fugro.com Multibeam Echo-Sounding (MBES) Coverage Offshore Area Shaded area offshore of Pt. Buchon collected in 2007 Red track lines = areas collected in 2009 Spatial resolution 1 m = water depths < 50 m 2 m = water depths > 50 m 2007 2009 2009 DCPP
www.fugro.com Pt. Buchon Multibeam Bathymetry collected as part of CA State Waters Mapping Program by CSU Monterey Bay Seafloor Mapping Lab 2006-2007
www.fugro.com Paleo-wave-cut platforms Tectonic strain gauge 120,000 Terrace
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www.fugro.com Paleoshorelines in Point Buchon area DCPP
www.fugro.com Details of Geologic Map North of Point Buchon
www.fugro.com Geologic map of Point Buchon area
www.fugro.com N40W N40W Faults Faults
www.fugro.com 50,000 50,000--year year--old old wavecut wavecut platform platform across the N40W Faults across the N40W Faults
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www.fugro.com Seismic line PBS-32 across the N40W Faults Paleo Wave-Cut Platform Tectonic Strain-Gauge Evidence of No Faulting in Past 50 to 60,000 Years
www.fugro.com Hosgri fault
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www.fugro.com Raw Multibeam Data Without Interpretation
www.fugro.com Preliminary Interpretation
www.fugro.com Gravity Anomoly Map USGS Gravity data
www.fugro.com From Cluff and Cluff, 1985 Relative Slip Rates Hosgri Olson/ San Luis Bay Shoreline
www.fugro.com Summary of 2009 Study Results
Microseismicity lineament defined by Hardebeck (USGS) a real feature
During 2008 and 2009 we collected extensive geophysical data to characterize the Shoreline fault
Shoreline fault zone is expressed in seafloor bathymetry and has 3 segments
Central and southern segments of the Shoreline fault zone are coincident with the microseismicity lineament
Microseismicity lineament diverges from the northern segment of the Shoreline fault zone and trends to the Hosgri fault zone with evidence of no surface faulting within at least 50,000 years
The Shoreline fault is a vertical, strike-slip fault that extends to
~ 10 km depth
Slip rate on the Shoreline fault zone is currently uncertain and is judged to be between 0.01 and 0.3 mm/yr
The geomorphic expression of the Shoreline fault zone is dominated by differential erosion
The Shoreline fault zone is 300 meters from the Intake structure and 600 meters from the Power Block
www.fugro.com Secondary Fault Rupture Given short distance (0.6 km) to power block, secondary fault rupture hazard is considered
www.fugro.com Lessons Learned From Investigating Strike-Slip Fault Ruptures Application of knowledge from experience in the investigation of historic and paleoseismic fault ruptures results in an understanding of the relationship between primary and secondary surface faulting hazards The threshold of surface faulting effects occur at
~ magnitude > 5.5 earthquakes Style of faulting is most important Near vertical Strike-slip faults result in simple narrow zones of surface rupture, except where the fault makes significant changes in strike direction Geometry of fault strike and changes in strike direction is very important
www.fugro.com Summary of First-Hand Experience with Strike-Slip Surface Fault Rupture Effects (primary fault rupture and secondary fault rupture)
- 1812 Bocono, Venezuela
- 1855 Wairarapa, New Zealand
- 1888 Hope, New Zealand
- 1872 Owens Valley, Nevada
- 1906 San Andreas, CA
- 1939 Ercincan, Turkey
- 1940 Imperial Valley, CA
- 1942 Erbaa-Niksar, Turkey
- 1943 Tosya, Turkey
- 1944 Gerede-Bolu, Turkey
- 1954 Fairview Peak, NV
- 1958 Fairweather, Alaska
- 1966 Parkfield, CA
- 1968 Borrego Mountain, CA
- 1968 Dashet-et-Bayez, Iran
- 1979 ImperialValley, CA
- 1979 Tabas, Iran
- 1979 Calaveras, CA
- 1976 Motagua, Guatemala
- 1992 Landers, CA
- 1999 Izmit, Turkey
- 1999 Duzce, Turkey
- 2001 Kunlun, Tibet
- 2002 Denli, Alaska
- 2006 Parkfield, CA
www.fugro.com Strike-Slip Surface Fault Rupture San Andreas fault, Central California Offset stream channels
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www.fugro.com 1976 Guatemala Strike-Slip Earthquake M 7.5, Rupture length Motagua fault, (1m to 3m LL)
School
www.fugro.com 1.5 m left slip
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www.fugro.com Nojima fault Japan 1995
www.fugro.com Nojima fault Surface fault rupture 1995 Kobe Earthquake M 6.9 Strike-Slip ~ 2 m RL Slip-rate ~ 6 mm/yr No secondary faulting
www.fugro.com Surface Fault Rupture Effects:
- 2 m P. faulting
- No sec. faulting Strong shaking Well-built house without damage
www.fugro.com 1999 Kocaeli, Turkey M 7.4 strike-slip 2 to 5.5 m Slip-rate ~10 mm/yr
www.fugro.com Right-slip 5.2 m
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www.fugro.com Surface Fault Rupture ~ 5 m, Rupture Width < 2 m Buildings close to fault not damaged by faulting
www.fugro.com 1992 Mw 7.3 Landers Earthquake Surface rupture length:
85 km Maximum riight-slip offset: 6 m
www.fugro.com 1992 Landers M = 7.3 RL = 2 m to 6 m
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www.fugro.com Landers Earthquake Kickapoo Fault
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www.fugro.com Landers Earthquake 1992 Complex step-over between Johnson Valley and Homestead Valley faults
www.fugro.com Denali Fault Alaska - Disrupted Stream Channels
www.fugro.com Denali Fault Alaska
www.fugro.com L.
L. Cluff Cluff, 1972
, 1972
www.fugro.com L.
L. Cluff Cluff, 1972
, 1972 Multiple Surface Rupture Events
< 1 m width of surface rupture
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L. Cluff Cluff, 1972
, 1972 Denali Fault Paleo Surface Rupture Zone Width of Multiple Ruptures During Past 12 to 15 Surface Rupturing Events
~ 10 m
www.fugro.com Susitna Glacier fault Epicenter Denali fault Totschunda fault Rupture length ~ 336 km Maximum right slip ~ 8.9 m Rupture propagation speed ~ 4 to 6 km/sec Fault rupture released the M7.9 Denali fault earthquake TAPS
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www.fugro.com L. Cluff 1973
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L. Cluff Cluff, 2003
, 2003 8.2 m
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www.fugro.com L. Cluff 2003
www.fugro.comL. Cluff 2003 Denali Fault 2002, 8.5 m Strike-Slip surface rupture constrained within 1.5 m width, except at strike change where surface rupture effects were
~ 20 m wide
www.fugro.com Denali Close -up enlarged surface rupture effects due to fault strike change
www.fugro.com Denali Fault 2002, 5.5 m Strike-Slip surface rupture constrained within 1.5 m width
www.fugro.com Denali Fault Primary Faulting 5-6 m, Very Narrow (< 2 m)
www.fugro.com Denali Strike-Slip ~ 8 m Surface Rupture Width ~ 1 m
www.fugro.com Denali Fault Alaska 2002
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www.fugro.com 8.5 m Strike-Slip Width of Surface Rupture ~ 1 m Denali Fault Alaska
www.fugro.com Impacts at DCPP Ground Motion y Deterministic 84th percentile (margin approach) y Assumed Fault Rupture Models Central segment
{ Length = 8-9 km, width = 10-12 km
{ M = 5.9 - 6.0 Central & southern segments
{ Length = 14-15 km, width = 10-12 km
{ M = 6.1 - 6.25 y Distance from DCPP 0.6 km from powerblock
www.fugro.com DCPP Ground Motion Sensitivity (empirical data)
www.fugro.com Impacts at DCPP Secondary Fault Deformation y Probabilistic approach (PRA approach)
Follows methodology of Petersen et al (2004)
Straight segment offshore DCPP, reduces chance of secondary ruptures
{
Used below average range of probability of secondary rupture from empirical models given by Petersen et al (2004) which is based on all strike-slip faults Location of potential secondary rupture
{ Shale unit is a zone of weaker rock y Assumed slip-rate 0.01 to 0.3 mm/yr y Assumed Fault Rupture Models Same as for ground motion
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www.fugro.com Secondary Deformation in Shale Unit
ASW pipes only safety-related SSC impacted by secondary deformation in shale unit y 8 Dresser couplings
Secondary deformation at susceptible segments of ASW pipes is very unlikely
NRC allows exclusion of very unlikely events y For Yucca Mtn post-closure: exclude events with annual chance < 1E-8 y 10 CFR 63.342
Impact on DCPP seismic CDF is negligible y Seismic CDF = 3.7E-5 (LTSP, 1988)
Annual Probability of Secondary Deformation at Susceptible Segments of ASW Pipes Disp (cm)
Central (M6.0)
Central &
Southern (M6.25) 1.0 4.2E 1.3E-7 8.0E 2.4E-7 2.0 1.7E 5.1E-10 2.3E 6.9E-8
www.fugro.com Shoreline Fault Investigations in 2010 Activities:
Integrate USGS geophysical data with multibeam data Complete interpretations of Shoreline fault with respect to location, association with regional structures, segmentation, activity rate, and earthquake magnitude and surface faulting potential