ML20099K459
| ML20099K459 | |
| Person / Time | |
|---|---|
| Site: | Beaver Valley |
| Issue date: | 02/28/1985 |
| From: | Christian J, Idriss I, Jan J DETROIT EDISON CO., STONE & WEBSTER ENGINEERING CORP., WOODWARD-CLYDE CONSULTANTS, INC. |
| To: | |
| Shared Package | |
| ML20099K450 | List: |
| References | |
| NUDOCS 8503200277 | |
| Download: ML20099K459 (112) | |
Text
SITE DEPENDENT RESPONSE SPECTRA BEAVER VALLEY POWER STATION - UNIT 2 Prepared for Duquesne Light Company Pittsburgh, Pennsylvania Reviewed and Approved by Duquesne Light Company Seismic Advisory Panel
,,)
- I NJ Dr. I.M. Idriss (Chairman)
Woodward-Clyde consultants
" T ( O WA.~
Dr./J.A. Jan // . J.T.~ Christian Duquesne Light Company Stone & Webster Engineering Corporation s
- J Mr. D.E. Shaw Dr. C.W. Lin ~
Consultant Westinghouse Electric Corporation Prepared by STONE & WEBSTER ENGINEERING CORPORATION BOSTON, MASSACHUSETTS (h
( ') FEBRUARY 1985 8503200277 850220 PDR ADOCK 05000412 E PDR
TABLE OF CONTENTS Section No. Title Page
-1.0 EXECUTIVE
SUMMARY
1-1 2.0 RESPONSE SPECTRA METHODOLOGY' 2-1
- 2.1 Earthquake. Magnitude 2-1
.2.1.1 -Design Earthquake .
2 2.1.2 -Appalachian Plateau Tectonic Provirce 2-2 2.1.3 ' Effects of Shallow Earthquakes . 2-3
-2.2 Earthquake Record Scaling Procedure 2-4 2.2.1 Eastern. United States Earthquakes. 2-4 2.2.2- Equivalent Western United States Earthquakes 2-4 2.2.3 Scaling Procedure 2-5 3.0 SITE MATCHED RESPONSE SPECTRA. 3-1 3.1 Effect.of Revised Scaling Law 3-1 3.2 Effect .of Velocity Contrast 3-2
-3.3 Vertical Re wonse Spectra 3-3 4.0 . SOIL RESPONSE ANALYSIS 4-1 4.1 Earthquake Record Data Base ~ 4-1 4 .1.~ 1 . . Selection Criteria 4-1
~4.1.2 Earthquake Records Selected 4-2
- 4.2 Soil Model 4-3 4.3 Results 4-4 5.0 SITE DEPENDENT RESPONSE SPECTRA 5-1
-5.1- Procedure 5-1 5.2 ~ Results 5-2 6.0 PROBABILISTIC ANALYSIS 6-1 6.1 Seismic Hazard Analysis . 6-1 6.1.1 Contributions of Tectonic Provinces
- and Seismic Source Zones 6-2 6.1.2- Seismic Hazard at BVPS-2 6-3 6.1.3 Summary 6-3 6.2 -Probability of Exceeding Response Spectra 6-3 6.2.1 Methodology 6-4 6.2.1.1 Recurrence Interval for Design Earthquake 6-5 6.2.1.2 Conditional Probability of Design Earthquake within 29 km of the Site 6-6 6.2.1.3 Probability of Exceeding Site Dependent Response Spectra 6-6 6.2.2 Results 6-6 6.3 Discussion 6-7
7.0 CONCLUSION
S 7-1
8.0 REFERENCES
8-1 O
TABLE OF CONTENTS (Cont)
Section No. Title Appendix 1. Nuclear Regulatory Conaission Response
. Spectra Action Items AppendiF. 2. Shallow Earthquakes Appendix 3. Shear Wave Velocity Contrast - Site Matched Recording Stations Appendix 4. Earthquake, Recording Station and-Corrected Acceleration Data Appendix 5. Soil Response Analysis: Unscaled Appendix 6. Site Dependent Response Spectra-Statistical Analysis Procedure O
i l O
(
l L
LIST OF TABLES
.]
j Table Title 3-1 Site Matched Ground Surface Earthquake Records Scaled to a Local Magnitude of 4.95 3-2 _ Rock Outcrop Records Scaled to a Local Magnitude of 4.95 Used to Evaluate Effect _of Shear Wave Velocity Contrast on Site Matched Response Spectra 4-1 Earthquake Data Base From SWEC (1984).
4-2 Rock Sites 4-3 Earthquake Records Considered r 4-4 Rock Outcrop Records Used in Scaled Soil Response Analysis 4-5 Rock Outcrop Records Available for Unscaled Soil Response Analysis i
6-1 Seismic Hazard Analysis [
l 6-2 Earthquakes Within 200 Miles of the Site and Within the ,
Appalachian Plateau Tectonic Province. +
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LIST OF FIGURES
[3 Figure Title 1-1 Site Dependent Response Spectra 1-2 Ratio of Vertical to Horizontal Site Matched Response Spectra 3-1 Site Matched Response Spectra: Scaled 3-2 Site Matched Response Spectra: Effect of Revised Scaling Law 3-3 Effect of Velocity Contrast on Ground Surface Response Spectra 3-4 Percent Increase in Response Spectra Ordinates Due to Change in Velocity Contrast Ratio 3-5 Site Matched Response Spectra: Adjusted for Shear Wave Velocity Contrast 3 Site Matched Vertical Response Spectra 3-7 Ratio of Vertical to Horizontal Site Matched Response Spectra 4-1 Soil Model 4-2 Strain Dependent Soil Parameters 4-3 Horizontal Response Spectra From Soil Response Analysis: Scaled
,_ 5-1 Site Dependent Response Spectra
\s 6-1 Epicenters with Intensity 2 V (MM) (1871-1977) 6-2 Tectonic Provinces 6-3 Seismic Zones 6-4 Seismic Hazard 6-5 Epicenters and Tectonic Provinces Within 200 Miles of the Site 6-6 Recurrence Relationship i
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.x SECTION 1 EXECUTIVE
SUMMARY
The Final ~ Safety Analysis Report (SWEC, 1983) presents the seismic design basis for the Beaver Valley Power Station - Unit 2 '(BVPS-2).-
In response to questions from the U.S. Nuclear Regulatory Commission (NRC), the' BVPS-2 -design response spectra were supported with additional ' analyses submitted in a report to the NRC in June, 1984 (SWEC,-1984).. The present report supplements the June,-1984, report.
The analyses described in the present report clearly demonstrate that the BVPS-2 design response _ spectra are appropriate when compared to response ' spectra determined by current state-of-the-art procedures.
Two suites of actual strong motion accelerograms, one recorded at stations-~with soil -conditions matching those of the site and the other recorded on rock and amplified analytically through the soil profile, 'give estimates of the anticipated response spectra due to a Safe Shutdown Earthquake (SSE) with a body-wave magnitude of 4.75. A combined estimate considering the.results of both methods together gives the site dependent response spectra for 5 percent damping shown in. Figure 1-1. The 50th percentile response spectrum falls well below the'BVPS-2. design spectrum. ~ The 84th percentile response spectrum closely. matches the design response spectrum above 6Hz and
' falls below it for all other frequencies, sometimes substantially.
Probabilistic analyses of seismic hazard show that the annual probability of equalling or exceeding the 50th percentile response O.. spectrum is on the order of 10 9 and is on the order of 10 5 for the 84th percentile response spectrum. The annual probability associated with the 50th percentile spectrum is comparable to values usually-acceptable for the SSE; the probability for the 84th percentile is substantially lower. A conventional seismic hazard analysis gives an annual probability of about 2x10 9 for the SSE acceleration of 0.125g.-
This' report responds to the additional issues outlined in Appendix 1 that were identified by the NRC during its review of the June', 1984 -
report. The results of the investigations performed are described in the subsequent sections .and are summarized below:
. The effect on the maximum earthquake potential for the site resulting from including the southeastern Ohio, Intensity VI-VII (MM) event of November,1926, within the Appalachian Plateau tectonic province is examined. The effects of shallow focal depth earthquakes on the intensity of the SSE is also considered. Neither of these issues affects the seismic hazard or the site dependent response spectra.
. The site matched response spectra analysis presented in SWEC (1984) is re-examined to evaluate the effects of (1) 1-1
-w._
A s
s- l
- the_use'of a revised, magnitude dependent scaling law, and !
- s ..(2) the difference in shear wave' velocity contrast between y them soil l and_ the--rock at the site matched recording
' stations compared to that at BVPS-2. The 50th percentile l
fj j
- and 84th percentile site matched response spectra computed-using the revised scaling law are about 10-percent lower [
than. those presented. in SWEC-(1984). The difference in shear wave velocity. contrast at BVPS-2 and _at the site [
matched. recording stations is accounted for by increasing
- the' revisedi50th percentile, and ,84th percentile site matched . response spectra at each frequency. The increase i
, - ranges between 1-percent and 49-percent and averages about j
' 16-percent for all frequencies. )
1 '
}
The' soil: response analysis presented by SWEC (1984) is R . -
(
L revised to include a larger, more recent earthquake record ;
b data base, and a revised,' magnitude ~ dependent scaling law .!
i is used to scale the amplified ground surface motions. !
V :
. The site -matched ' response spectra adjusted for velocity !
contrast and the soil response analysis response spectra !
- . are combined statistically to determine the site dependent !
- response spectra shown-in Figure 1-1.. .
r
. Two related probability analyses are performed to estimate !
- the annual. probability of exceeding the 50th .and 84th percentile site dependent response spectra. The first is .;
a conventional seismic hazard analysis using three seismic
,L ' [- - source models: two tectonic province models and a seismic i
12 source zone model. The analyses lead to .a general i
, understanding of the seismic hazard at BVPS-2. The tectonic province model approach concludes that almost all of the hazard at the site is contributed by the portion of- ,
' the Appalachian Plateau' province in the -site region. f Similarly, with the seismic source' zone approach, background seismicity-is the major contributor. Based on j the results of the conventional seismic hazard analysis, a
- - second, more detailed,' analysis is made to consider the seismicity of only the region around the site. The 50th .
percentile response spectrum has an annual probability of i exceedence~ that is lower than values that have been ;
accepted for the safe shutdown earthquake (SSE), and, _l therefore, represents an acceptable level of conservatism. !
- The 84th percentile has an annual probability of exceedence that is very much lower.
P . ' The site matched response spectra analysis approach also -[
demonstrates that the use of two-thirds as the ratio of !
[ vertical to horizontal response spectra is conservative. l
- The ratio of vertical to horizontal site matched response ;
spectra, shown in Figure 1-2, is less than two-thirds for
, all frequencies. j i
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FIGURE 1 -2 RATIO OF VERTICAL TO 4
HORIZONTAL SITE MATCHED i RESPONSE SPECTRA BEAVER VALLEY POWER STATION-UNIT 2 STONE G WEBSTER ENGINEERING CORPORATION I
4
SECTION 2
/ ' RESPONSE SPECTRA METHODOLOGY Two -approaches were used to determine horizontal, ground surface response spectra for the safe shutdown earthquake (SSE)^ taking into consideration the geology, seismicity and local soil conditions at BVPS-2. lThe' approaches were:
. Site matched response spectra analysis
, .= -- Soil. response analysis The- site matched response spectra analysis used ground surface records.from earthquakes that were recorded _at accelerograph stations with . subsurface conditions matched as closely as possible to the BVPS-2 site. Response spectra for 5-percent damping were computed from these ground surface. earthquake records and statistically
-analyzed to -determine a 50th and an 84th percentile response spectrum.
The soil response analysis used records from earthquakes recorded at accelerograph stations founded on rock outcrops. These recordings were. amplified through the BVPS-2 -in situ soil profile using the l computer program SHAKE (Schnabel et al, 1972). Ground surface response. spectra for 5-percent damping were determined and statistically analyzed to obtain a 50th and an 84th percentile
[ response . spectrum. The earthquake record data base used in the soil
\ response analysis included more recent earthquakes than had been used
. in the original analysis presented by SWEC (1984).
Statistical analysis of ' individual response spectra from both approaches was performed assuming that the response spectra ordinates were log-normally distributed.
A magnitude dependent, earthquake scaling law, developed from the attenuation. relationships presented by Nuttli (1984), was used to scale - the earthquake records to the magnitude corresponding tc the BVPS-2 SSE for both-the site matched analysis and the soil response
. analysis.
. ' 2.1 EARTHQUAKE MAGNITUDE The BVPS-2 design earthquake (SSE) was established to be equivalent to an intensity VI (MM) event occurring near the site (SWEC, 1983).
Since magnitude, rather than intensity, is a more reliable measure of earthquake source strength, the earthquake records used in both the site matched analysis and the soil response analysis were selected on the basis of magnitude. The SSE intensity was, therefore, converted to a corresponding eastern United States body-wave magnitude. The convention of using local magnitude for western United States earthquakes required an additional relationship to establish a i O- 2-1 l
b {
r western' local magnitude equivalent to the eastern -SSE body-wave !
magnitude.. "
y" -: The . design earthquake intensity was established considering the t historical seismicity-and the tectonic provinces around the BVPS-2 l site (SWEC,.1983).. The.NRC raised the issue, during.their review of '
SWEC (1984), chat the western boundary of' the Appalachian- Plateau i tectonic province, in which the, site is located, should not exclude an' intensity ?I-VII (HM).earthquakei that occurred in southeastern. ,
. ohio in November, 1926. The NRC~also requested that.the possible ;
effects'of: shallow focal depth earthquakes on the -selection of. the L
~ design = earthquake, be evaluated. Neither of these concerns affects !
the design earthquake. !
L
, 2.1.1 . Design Earthquake- , :
s
- The . design carthquake intensity was converted to magnit'ude using the l empirical correlation.given by Nuttli and Herrmann (1978)
ab = 0.5Io + 1.75' (mb i 0.5 units) (Eq 2-1), }
. i
- where: mb = body-wave magnitude f Io = epicentral intensity r 4
The SSE Intensity lVI (MM) event' is'thus converted to a body-wave !
-magnitude of 4.75 1 0.5. *
.Most'of the' currently available strong motion records are for western l United States earthquakes. Chung and Bernreuter. (1980) found that O .the body-wave magnitudes of western United States ' earthquakes were about.0.3 units lower than similar eastern United States earthquakes. ,
Since- local magnitude, rather..than body-wave magnitude, is generally '
mused as an indicator of western earthquake source strength, Chung and
- Bernreuter (1980) developed the following empirical . correlation between the body-wave magnitude of an eastern earthquake and the local magnitude of an equivalent western earthquake
Mg (west) = 0.57 + 0.92mb (east) (Eq 2-2)
.Therefore,.the SSE body-wave magnitude of 4.75 1 0.5 is equivalent to a western local-magnitude of 4.95 1 0.5. Records of the 1976 Friuli,
-Italy earthquakes Lwere considered 'to be similar to western United 1 States earthquakes. f 2.1.2 Appalachian Plateau Tectonic Province Thei western. boundary of the Appalachian Plateau tectonic province f (Figure 6-5) was -established as the westernmost limit of known ;
structural geologic features associated with the Allegheny orogeny'of !
-Permian age (SWEC, 1983). Occurring about 250 million years- ago, Jthis is the most recent tectonic episode to have affected the site ;
region. '
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, I 2-2 i
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' The 1 maximum ~ earthquake: potential.(SSE)'for the site was determined from the tectonic province approach to be equivalent to an intensity h, VI '(MM) event.- The, western boundary of the Appalachian Plateau l
V; . tectonic province excluded the November, 1926 intensity _VI-VII (MM)'
earthquake.-_.that occurred in southeastern Ohio. However, there is no effect.on'the design earthquake even if-the November 1926 event- is assumed =to_ have occurred in the Appalachian Plateau tectonic
- province, rather than in the adjacent Central Stable Region. '
The November, 1926' earthquake has been identified by Nuttli and Brill (1981).to be a'_ shallow focal depth event (<3 km). It was estimated
~
to 'have' a body-wave magnitude of 3.4 and a felt area of only 350
' square miles,Jsuggesting that it was not felt beyond about 10 miles
- from the epicenter.. It is shown in Section 2.1.3 that shallow focal
- depth earthquakes do = not present a seismic hazard to BVPS-2.
Furthermore, this earthquake was conservatively included in the
- probabilistic' assessment of seismic risk at the. site presented in Section 6.-
- 2.1.3 Effects of Shallow Earthquakes Earthquakes with shallow focal depths, having lower magnitudes and smaller-felt areas than other earthquakes with the same epicentral intensity, have occurred within 200 miles of the site and within the Appalachian' Plateau tectonic province. Similar earthquakes could occur in the future. in the vicinity of. BVPS-2; however, the occurrence of these events is expected to be infrequent and the
, . resulting ground motions are not expected to present a seismic hazard to BVPS-2 plant structures. Appendix 2 contains a more detailed
- -~ (f )T discussion of the effects of shallow earthquakes.
Analysis _ of several strong motion records from shallow events that
~ occurred in the eastern United States in 1978 and 1979 indicated that
--peak. accelerations resulted from high frequency spikes of short duration which do not represent significant energy input to typical power plant structures (McGuire, 1982). ' Damage results predominantly from long duration shaking (Trifunac, 1972). Brady et al (1981)
< found that the peak accelerations in the records occurred at frequencies'as high as 25-30 Hz, and that the duration of strong ground motion.was between 1/2 and 1 second. The lack of correlation between the high peak accelerations for these shallow events and damage to any facility within one or two kilometers of the epicenter
-. suggests ~that high accelerations alone are not indicative of potential damage.
While shallow earthquakes may occur in the vicinity of BVPS-2, the likelihood is very low and the maximum expected body-wave magnitude is 3.8, - which is - less than the SSE body-wave magnitude of 4.75.
Predicted' accelerations at the site range from 0.024g to 0.214g but these predictions. are very uncertain. Given that shallow eastern earthquakes produce high accelerations of short duration at
- predominantly high frequencies which do not damage engineered
. structures,_and that BVPS-2 structures ate designed for a normal 2-3
- "' ~
M
- focal--depth 1 type- of earthquake with a peak ground acceleration of
~
0.125g, the _ design ~ is conservative for the effects of shallow G_
(
- earthquakes.
.u r
- 2.2. EARTHQUAKE RECORD SCALING PROCEDURE j Ideally, --records of earthquakes having magnitudes within the limits defined for the design earthquake would be- used directly, without j scaling, in the site matched or soil response analyses. However,.the !
number of. suitable recordings meeting'this criterion was too small to . !
represent a ~ valid = statistical sample,- and therefore, a magnitude j
- scaling law and procedure _ were developed so that records of !
earthquake's having magnitudes outside of the limits could be used. i l
2.2.1 ' Eastern United States Earthquakes !
The scaling law . was developed 'from' the attenuation relationship
- presented by Nuttli (1984) for South Carolina earthquakes which has ,
the forms i i
. log g = A + Bmb - 0.83 (Ra + ha}1/2 . CR (Eq 2-3) f where: ah
- peak horizontal acceleration in em/sec a !
mb = body-wave magnitude .
'R = epicentral distance in km t h -=. focal depth'in km !
A, B and C = empirical constants B = 0.5 for mb 2 4.5 and 0.25 for mb < 4.5
)
The form of this relationship is. generally the same as that presented i by Nuttli and Herrmann (1984) for Mississippi Valley earthquakes. l The values for the constant term, B, are valid for central and !
eastern United States earthquakes (Nuttli, 1984a). .
l
- Assuming that- all. of the variables in Equation 2-3 are constant except for magnitude leads to the following relations for the change !
, in acceleration as a function of the change in magnitude !
. i Alog g = 0.5 Am for m t 4.5 b
.(Eq 2-4a) f
[
1 Alog g = 0.25 Amb- # "b< 4.5 (Eq 2-4b)
These relations were used to scale eastern United States earthquake !
j; records to the SSE body-wave magnitude of 4.75. ;
_2.2.2 Equivalent Western United States Earthquakes f Comparing two eastern events with,two equivalent western events using l
Equation 2-2 ' leads to the following expressions !
Amb (east) = 1.09 AMg (west) (Eq 2-5) s I
l 2-4 i
t r L _ ___
n.
Substituting Equation 2-5 into Equations 2-4a and 2-4b leads to the- :
m -scaling" law used to scale' equivalent western United States earthquake j
? records to a local magnitude of 4.953
'{
!V !
i A log a
- h. =.0.54~A M g for M g2 4.7- (Eq 2-6a) ;
y Alogay=0.27 AM g for ML < 4.7. (Eq 2-6b) !
i
.' Equation 2-6a Lis' the same scaling law presented by SWEC (1984) and used to scale-; earthquakes regardless of local magnitude; however, !
' differentiation.'between local _ magnitudes greater.than or less than !
4.7 was not made by' SWEC -(1984). The use of Equation 2-6b~ for .
earthquakes. with local magnitudes less than 4.7 results in smaller f scaling factors'than-those.used in the original analyses, j i
'2.2.3 : Scaling Procedure.
In. the site ' matched response spectra analyses, ground surface time l
.historier were scaled.to the design magnitude and then response ;
spectra were computed. In the soil response analysis, rock outcrop j records were input to.the' SHAKE'model without scaling, and amplified (
,through the .BVPS-2 soil profile. The resulting ground surface time '
histories were then scaled to the design magnitude, and response '
-spectra were computed.
j The scaling procedure for the soil response analysis is appropriate ;
for two' reasons. First, the Nuttli (1984) attenuation relationships '
-. used to develop the scaling law were determined from ground motion data obtained at soil sites and may not be appropriate for scaling ;
w/ rock records directly (Nuttli and Hermann, 1984). Scaling the output of. the soil response analyses, rather than the input rock motion, is, t therefore, consistent with the 'use of the Nuttli attenuation ;
relationships.
Second, scaling the ground surface time histories from the soil
^
- . . response analyses is consistent with scaling the site matched, ground '
F ~ surface time histories prior to computing response spectra. The site
[ matched approach used recorded ground surface time histories which were the result' of bedrock motions amplified through a subsurface ;
l profile comparable to that of - BVPS-2. These time histories were ;
l~ scaled to 'the design magnitude prior to computing response spectra !
.and as a result, scaling the. output is implied in the site matched i approach. '
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E L
SECTION 3 SITE MATCHED RESPONSE SPECTRA The _ site ~ matched response spectra analysis presented in SWEC (1984) was re-examined to ~ evaluate the effects of: (1) the revised, magnitude dependent scaling law represented by Equations 2-6a and 2-6b, and (2) the difference in shear wave velocity contrast between the soil and rock at the site matched recording stations compared to that.at BVPS-2. The site matched response spectra analysis was also used to demonstrate that the use of two-thirds as the ratio of vertical to horizontal response spectra is conservative for all frequencies.
-The 50th percentile and the 84th percentile response spectra computed using the revised scaling law are about 10 percent lower than those presented in SWEC (1984).
The revised 50th percentile and 84th percentile response spectra were
. increased at each frequency by a factor which accounts for the difference between the shear wave velocity contrast at BVPS-2 and the average shear wave velocity contrast at the California site matched recording stations. The percentage increase varied between about one
' percent and 49-percent and averaged about 16-percent for. all
' frequencies.
The ratio of vertical to horizontal site matched response spectra-was shown to be less than two-thirds for all frequencies. The ratio varies between-0.28 and 0.64'and averages about 0.5.
3.1 EFFECT OF REVISED SCALING LAW The 50th percentile and 84th percentile site matched response spectra presented by SWEC (1984), and shown in Figure 3-1, were determined from the suite of eighteen site matched earthquake records shown in Table 3-1. These records were scaled to a local magnitude of 4.95 using Equation 2-6a for all magnitudes. For comparison, scaling factors determined using the revised, magnitude dependent scaling law, namely Equations 2-6a and 2-6b, are also shown in Table 3-1.
The scaling factors of 6 component recordings out of a total of 18 were lowered by using the revised scaling law.
To evaluate the effect of the new scaling law, individual response spectra were recomputed for the earthquake records listed in Table 3-1 using the revised scaling factors. The 50th percentile and the 84th percentile' response spectra are shown in Figure 3-2, which also shows those presented in SWEC (1984) for comparison. The effect of the revised scaling law was to reduce the 50th percentile and the 84th percentile response spectra shown 'by SWEC (1984) by about 10 percent for all frequencies.
3-1 1
3.2 EFFECT OF VELOCITY CONTRAST n )
( ) A study was made to evaluate the change in ground surface response
's _/ spectra caused by changes in the shear wave velocity contrast between the rock and the overlying soil. The purpose of the analysis was to adjust the 50th percentile and the 84th percentile site matched response spectra to account for the difference between the shear wave velocity contrast at the " site matched" California recording stations and BVPS-2.
A normalizing parameter called velocity contrast ratio (VCR) was defined as the ratio of the shear wave velocity of the rock or rock-like layer divided by the shear wave velocity of the immediately overlying soil layer. The average VCR for the site matched California recording stations is about 2.0 (Appendix 3), and the VCR at BVPS-2 is 4.2 (Figure 4-1).
To quantify the effect on grou. ' surface response spectra caused by changes in velocity contrast ratio, a soil response analysis was performed. Each rock outcrop time history listed in Table 3-2 was amplified through the BVPS-2 in situ soil profile and a ground surface response spectrum for 5-percent structural damping was computed.(18 A 50th percentile response spectrum was computed from the suite of individual response spectra assuming a log-normal distribution of the spectral ordinates.
Three values of VCR were investigated: 4.2, corresponding to BVPS-2; 7-~s 2.0, corresponding to the average VCR for the site matched recording f j stations; and 1.0 as the limiting value. The resulting 50th A' percentile response spectra, shown in Figure 3-3, indicate that as the VCR decreases, the spectral ordinates decrease, as expected.
With a decrease in the VCR; i.e., as the shear wave velocity of the rock approaches that of the soil, more of the energy of the waves reflected at the free surface of the soil is reabsorbed by the rock.
This effect is referred to as radiation or geometric damping.
Conversely, as the VCR increases, more of the energy remains in the soil layer.
Figure 3-4 shows the percentage change in spectral ordinates as a function of frequency and change in VCR. The curves are shown for a change in VCR from 1.0 to 4.2, the limiting case, and from 2.0 to 4.2. Each curve represents the 50th percentile percent change 1The records and scaling factors shown in Table 3-2 were used in the soil response analysis presented in SWEC (1984). The rock out-crop time histories were scaled prior to amplifying them through the BVPS-2 in-situ profile in contrast to the procedure described in Section 2.2.3. The scaling procedure is, however, not important since the objective of the analysis was to evaluate the effect on ground surface spectra due to changes in the shear wave velocity 7'~g of the rock.
l \'~' l
- 3-2 t
f f
lj computed at each. frequency for each earthquake record used in the l M[
- analysis. l P( Since ~-the average 'VCR for the site matched recording stations is about'2.0-and the VCR at BVPS-2 is 4.2, the 50th and 84th percentile l
!, site'. matched response spectra computed using the revised scaling law l (Figure 3-2) were increased'at each frequency by the percent change i
, . appropriate for an increase in VCR from 2.0 to 4.2. The resulting !
, adjusted site matched response spectra are shown in Figure 3-5. The '
BVPS-2 : design response spectrum envelopes the adjusted site matched 4
response. spectra at all frequencies. t an 3.3 .VERTICAI, RESPONSE SPECTRA j
- BVPS-2 vertical design response spectra are taken as two-thirds of l
[ the corresponding horizontal design response spectra and SWEC (1984)
~ demonstrated: that .this is consistent with'available_ earthquake data .
from the United States and Japan. The site matched response spectra !
. approach was used to provide additional support for the use of *
- two-thirds as the ratio of vertical to horizontal response spectra.
3
- Response spectra.for 5 percent structural damping were computed from the vertical components of the site matched ground surface records >
. _ listed in Table 3-1. The earthquake records were scaled according to .!
the' scaling law used in SWEC (1984) and given by Equation 2-6a(2).-
I The 50th percentile and the 84th percentile vertical, site matched i response spectra are shown in Figure 3-6,. compared to the ;
E corresponding BVPS-2 vertical. design spectrum. The BVPS-2 vertical ;
,- design response' spectrum conservatively envelopes the vertical site !
- L- matched spectra at all frequencies. ;
Ratios-~of .the" vertical to the horizontal site matched response
~
spectra are shown in Figure 3-7 as-a function of frequency. They !
.were computed from the 50th percentile vertical response spectrum a shown in Figure 3-6 and the 50th percentile horizontal response i spectrum shown in Figure 3-1. The ratios vary between 0.28 and 0.64 .
- . and average about 0.5 for all frequencies. !
i f' _In conclusion, the results indicate that the selection of two-thirds i as the ratio of' vertical to horizontal response spectra is' a i conservative one, i o
t i
I L l r
2Section 3.1 shows that the use of the original scaling factors for L 4
this suite of records is conservative. Also, the objective ~of this analysis .was to compute the ratio' of vertical to horizontal response i spectra. Since the vertical and horizontal components of the same v i . event were scaled using the same scaling factor, the ratio of re- I
! .sponse spectra is not affected by not using the revised scaling law. [
o
. 3-3 I r
I
' I
- 1
) (% (
O d V.
TABLE 3-1 SITE MATCHED GROUND SURFACE EARTHQUAKE RECORDS SCALED TO A LOCAL MAGNITUDE OF 4.95 Ep icent ra l Sca lino Factor CIT Date Epicent ra l Local Record ing Distance SWEC EQN. Reco rd Year Month pay Location Maanitude Station '(km) Component i19841 2-6aarb No.I11 1954 12 21 Eureka, CA 6.5 Federa l Bldg. 6 N79E 0.146 0.146 A-008 Eureka, CA S11E 1957 03 22 San Francisco, CA 5.3 State Bldg. 13 N09E 0.65 0.65 A-016 San Francisco, CA S81W Alexander Bldg. 14 N09W 0.65 0.65 A-014 San Francisco, CA N81E 1957 03 22 San Francisco, CA 4.4 Alexander Bldg. 16 N09W 1.98 1.65 V-323 San Francisco, CA N81E City Hall, 24 N26E 1.98 1.65 A-017 Oakland, CA 564E 1962 09 04 Northern CA 5.0 . Fede ra l B l dg . 18 N79E 1.0(2) 0.94 V-330 Eureka, CA S11E 1965 07 15 Southern CA 4.0 Old Ridge Rte. 14 E 3.26 2.11 V-331 Castaic, CA S 1970 09 12 Lytle Creek, CA 5.4 6074 Pa rk Dr. 14 S65E 0.572 0.572 W-334 Wrightwood, CA S25W 1971 02 09 San Fernando, CA 6.4 Old Ridge Rte. 29 N21E 0.165 0.165 D-056 Casta ic, CA N69W NOTE:
(1) Ca l i fornia institute of Technology reference number, Trifunac and Lee (1973)
(2) This scaling factor should have been 0.94 and has been revised for the present analysis i
1 of 1
Y
- j ,. :- t i TABLE 3-2 ROCK OUTCROP RECORDS SCALED TO A LOCAL MAGNITUOE OF 4.95 r
USED TO EVALUATE EFFECT OF SHEAR WAVE VELOCITY CONTRAST ON SITE MATCHED RESPONSE SPECTRA Ep icent ra l' CIT Date Epicenter Local Recording Distance Scaling ' Record -
yggr Month Day " Location Maenitude Station fkal Component Factorf 21 No.f31 1935 10 31 Helena, MT 6.0 Ca rroll Col lege 6 EW 0.271 .B-025- '
Hetena, MT NS- /
1935 10 31 Helena, MT 4.0(1) Fede ra l Bldg. 6 NS 3.26' U-295 Helena, MT. -EW' 1935 11 21 Helena, MT 3.8(1) Fede ra l Bldg. 6 EW- 4.18 U-296-Helena, MT NS 1935 11 28 Helena, MT 5.0(1) Federa l Bldg. 6 NS 1.0 U-297 Helena, MT -- EW 1957 03 22 San Francisco, CA 5.3 .Colden Cate Pk. 11,
~
S80E 0.65 A-015 -
San Francisco, CA N10E
~
1970 09 12 Lytle Creek, CA 5.4 Allen Ranch 19 S05W 0.572 W-335 Ceda r Springs, .CA S85E 1971 02 09 San Fernando, CA 6.4 Array No. 4 29 S69E 0.165 J-142 -
Lake Hughes, CA S21W
, Array No. 9 29 N21E 0.165 J-143 Lake Hughes, CA N69W Array No. 12 24 N69W 0.165' J-144 Lake Hughes, CA N21E NOTES:
(1) Estimated by Kanomori and Jennings (1978)
(2) From SWEC (1984)
(3) California Institute of Technology reference number, Trifunac and Lee (1973) 1 of I f
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LEGEND:
VCR e 4.2 FIGURE 3-3
-- vcR = 2.
EFFECT OF VELOCITY CONTRAST
vcR e 1.o ON GROUND SURFACE RESPONSE SPECTRA
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EACH CURVE REPRESENTS THE SOTH PERCENTILE PERCENT CHANGE IN SPECTRAL ORDINATES FOR THE NOTED CHANGE IN VELOCITY CONTRAST RATIO (VCR)
FIGURE 3-4 PERCENT INCREASE IN RESPONSE SPECTRA ORDINATES DUETO CHANGE IN VELOCITY CONTRAST RATIO
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,v BEAVER VALLEY POWER STATION-UNIT 2 STONE & WE8 STER ENGINEERING CORPORATION
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SECTION 4 Dl
-d SOIL RESPONSE ANALYSIS ,
The soil response analysis presented by SWEC (1984) was performed using 18 component recordings of 9 earthquakes which were made at accelerograph stations founded on sites described as rock. Following its review of SWEC (1984), the NRC suggested a number of additional earthquake records- which might be included in the earthquake record data base. Accordingly, the . original soil response analysis was revised to include a larger and 'more recent set of earthquake records.
The computer program SHAKE (Schnabel, et al, 1972) was used to determine the ground surface response caused by earthquake records input at the bedrock surface and amplified through the BVPS-2 in-situ soil profile. . Ground surface response spectra for 5-percent structural damping were determined for each earthquake record and then. statistically analyzed to determine 50th percentile and 84th percentile response spectra for comparison with the BVPS-2 design response spectrum.
4.1 EARTHQUAKE RECORD DATA BASE The earthquake record . data base used by SWEC (1984) is given in Table 4-1. The recordings were made at accelerograph stations described as . rock sites by SW-AA (1980). Table 4-2 lists the
. A)('v- earthquakes suggested by the NRC for consideration. Tables 4-1 and 4-2 were combined chronologically to form Table 4-3.
The earthquakes listed in Table 4-3 and the site conditions at the associated accelerograph stations were reviewed and documented. The magnitude and epicentral distance associated with each record were verified, as well as whether or not the recording station was founded on rock and represented free-field rock motion which would be suitable for input to the soil response analysis. Details of this effort are provided in Appendix 4. Table 4-3 includes a summary of the additional information obtained and some rainor correc'tions to the original data shown in Tables 4-1 and 4'-2.
4.1.1 Selection Criteria Based on the magnitude of the SSE established in Section 2.1, the
- earthquakes considered for use without scaling had magnitudes falling within the following limits
. For eastern United States earthquakes: 4.25 $ mb 5 5.25
! . For western United States and Italian earthquakes: 4.45 5 Ng $ 5.45 j (')
v 4-1 I
i-
-To increase the number of earthquakes in the data base, the scaling law described in Section 2.2 was used to scale records up or down to a--magnitude corresponding to the BVPS-2 SSE. Thus, two earthquake k data bases were formed: one containing records within 0.5 magnitude units of the BVPS-2 SSE, which were used without scaling, and another containing those same records; plus additional records for events falling more than 0.5 magnitude units from the BVPS-2 SSE. All of the records in the latter data base were scaled to the BVPS-2 SSE.
To~ limit the diminution of. the strength of the earthquake due to attenuation effects, the selection process chose earthquake records recorded at accelerograph stations with epicentral distances of about 25 km. or less.
Earthquake records selected were those recorded at accelerograph stations founded on rock outcrops. A criterion of free field rock motion was used to remove any bias created by either geometric effects or rock-structure interaction effects.
4.1.2 Earthquake Records Selected The final earthquake data base was compiled by selecting the records listed in Table 4-3 which met the.: selection criteria. - Thirty-six component recordings of 17 earthquakes were eliminated for the following reasons:
. Three of the 1935 Helena, Montana earthquakes were removed because the magnitudes were estimated and not computed instrumentally (Ref. Nos. 2,3, and 4).
. The March 22, 1957, San Francisco earthquake recorded at Golden Gate Park was removed because of the fractured nature '
of the rock at the site (Ref. No. 5).
. The records of the February 9, 1971, San Fe'rnando earthquake made at Lake Hughes Array No. 9 and No. 12 were removed because of 9 to 10 ft. of soil underlying the recording stations (Ref. Nos. 9 and 10).
. The January 12 and June 7, 1975, Cape Mendocino earthquakes are considered to be subduction plate border events and were removed because they had very disimilar mechanisms than the remaining western United States events (Idriss, 1984) (Ref.
Nos. 11 and 12).
. The August 1, 1975, Oroville, CA, earthquake recorded at the Oroville Dam was removed since the recording station was located on the crest of the earthfill dam and not on rock (Ref. No. 13).
. Three of the 1975 Oroville Aftershocks recorded at Johnson Ranch were removed because the station was founded on 10 meters of sediments (Ref. Nos.15,16 and 18).
4-2
. Records L of -the - 1976 Friuli, Italy events obtained at Somplago (D) were removed because the station was located in
-: .a tunnel 260 meters below the ground surface and the records
- could'not.be considered outcrop recordings (Ref. Nos. 20, 23 and 24).
.. The ' August? ' 13 ,._1978, Santa Barbara earthquake was removed because-the recording station was founded on' a. floor slab supported on caissons extending through 13 ft of soil and founded in rock, 'rather than directly on rock (Ref. No.
26).
+ The January 26, 1980, Livermore,'CA earthquake is currently being digitized by the USGS and will not be. available.
(Ref.'No. 30)..
. The -records of the March 31, 1982 New Hampshire earthquake recorded on the right abutment of the Franklin Falls dam may have been significantly affected by the site geometry and were, therefore, removed.
Table. 4-4 lists the 12 earthquakes with 28 component recordings remaining in the data base. They represent the total set of records which were scaled to a magnitude corresponding to the BVPS-2 SSE.
Table 4-5, a subset. of Table 4-4, lists five earthquakes with 10 component recordings that were available for use directly ~without scaling. The number of records is, however, too small and does not represent a statistically significant data base for a soil response analysis, r
4.2' SOIL HODEL The original scil response analysis presented in SWEC (1984) considered two soil profile models: one for soils within the portion of the main plant area affected by the soil densification program and one for in-situ soils outside of the densified area. In the . revised soil response analysis, only the in-situ soil profile, shown in Figure 4-1, was used as representative of free field soil conditions appropriate for determining response spectra applicable to the BVPS-2 site. The densified area profile was not used because it reflects localized soil conditions beneath only the northern 50 percent of the main plant area and is not representative of soil conditions throughout the site.
- The SHAKE program iterates to obtain values of soil shear modulus and damping that are compatible with the strain levels induced by earthquake motions. The shear moduli corresponding to the shear wave velocities shown in Figure 4-1 represent low strain or maximum values. The strain dependent variations of shear modulus and damping
- used'in the analysis were based on the data presented by Seed and Idriss (1970), and are shown in Figure 4-2.
4-3
4.3 RESULTS
-(s[] The suite of scaled earthquake records listed in Table 4-4 was used to compute.50th and 84th percentile ground surface re'sponse spectra.
The number of unscaled earthquake records listed in Table 4-5 is too small to.be statistically significant. Additional discussion of the unscaled analysis is provided in Appendix 5.
The results of the scaled soil response analysis are shown in Figure 4-3. The 50th percentile response spectrum is less than the BVPS-2 design response spectrum for all frequencies. The 84th percentile response spectrum is less than the BVPS-2 design response spectrum for frequencies less than 4 Hz and exceeds the BVPS-2 design response spectrum above 4 Hz.
Section 6 shows that the annual probability of exceeding the 50th percentile response spectrum is approximately 10-4 and represents an acceptable margin of seismic safety that is commensurate with generally accepted probability levels of seismic safety. The probability of exceeding the 84th percentile is approximately an order of magnitude smaller.
O
'l
\ ( 'V. :l TABLE 4-1
. EARTHQUAKE DATA BASE '
FROM SWEC (1984)
Epicenter CIT
. Epicenter LocaI Distance Reco rd Recording Year & Day Location Moonitude fkm) No.(2) _ station 1935 10 31 Helena, MT 6.0 6.6 B-025 Carroll Col tege Helena, MT 1935 10 31 Helena, MT 4'0(1)
. 5.8 U-295 Fede ra l Bldg.
Helena, MT 1935 11 21 Helena, MT 3.8(1) 5.8 U-296 rederal Bldg.
Helena, MT 1935 11 28 Helena, MT 5.0(1) 5.8 U-297 Fede ra l Bldg.
Helena, MT 1957 03 22 San Francisco, CA 5.3 11.2 A-015 Golden Gate Pk.
San Francisco, CA 1970 09 12 Lyt te Creek. . cA 5.4 19.2 W-335 Allen Ranch-Cedar Springs, CA 1971 02 09 San Fernando, CA 6.4 28.8 J-142 Array No. 4 Lake Hughes, CA 28.6 J-143 Array No. 9 Lake Hughes, CA 24.0 J-144 Array No. 12 Lake Hughes, CA MOTES:
(1) Estimated by Kanamori and Jennings (1978)
(2) Ca l i fo rn ia institute of Technology reference number, Trifunac and Lee (1973) 1 of I
TABLE 4-2 N ROCK SITES (1)
M
-Date Station Code and Name i Dist (km)-
1)'_10/31/35 U295 - Helena Feder. Bldg. (5.0) 6 2)- 10/31/35 B025 - Helena carroll Coll. 6.0 7
- 3) 11/28/35 U297 - Helena Feder. Bldg.
(5.0) 6
- 4) -6/28/66 B037, - Temblor 5.6 (20)
- 5) '9/12/70 W335 - Allen Ranch 5.4 19
- 6) 1/12/75 PC175 - Cape Mendocino 5.2 27 7). 6/7/76 PC675 - Cape Mendocino 5.2 22
- 8) 8/1/75 OD875 - Oroville Dam 5.7 11
- 9) 8/1/75 0S875 - Oroville Seis. Stat. 5.7 12
- 10) 8/6/75 J350 - (Johnson Ranch) 4.7 13
- 11) 8/8/75 J700 - (Johnson Ranch) 4.9 11.
- 12) 8/8/75 6700 - Oroville #6 4.9 (5)
- 13) 9/27/75 J234 - (Johnson Ranch) 4.6 (13)
- 14) 9/27/75 8234 - Oroville #8 4.6 (11)
- 15) 9/11/76 I142 - Somplago 5.9 6
- 16) 9/11/76 I139 - San Rocco 5.9 14
- 17) 9/11/76 I132 - San Rocco 5.5 15
- 18) 9/11/76 I134 - Somplago 5.5 10
- 19) 9/15/76 .1159 - Sompla9a 5.0 11
- 20) 9/15/76 I169 - San Rocco 6.0 19
- 21) 8/13/78 North Hall (Goleta) 5.1 (4)
- 22) 8/6/79 San Martin, C.C. 5.9 1
- 23) 8/6/79 (Gilroy #1) 5.9 8 1 of 2
TABLE 4-2 (Cont)
Date Station Code and Name ML Dist (km)
Gilroy #6 3/31/82 Mitchell Lake, 4.8 Aftershock New Brunswick 1/18/82 Franklin Falls Dam 4.7 1/26/80 Livermore, CA Morgan Territory '
Park NOTE:
(1) Provided by Geosciences Branch, U.S. NRC at August 16, 1984 meeting with DLC and SWEC.
O O
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l TABLE 4-3 EARTHQUAKE RECORDS CONSIDERED Re f. Date Local Epicentral Record Reco rd i ng - Site Conditions NO._ Yea r & pay Earthauake Name Meanitude Distance fkm) No. Station at Recordine Station 1 1935 10 31 Helena, MT 6.0 6 8-025 Ca rrol I college Limestone Helena, MT 2.** 1935 10 31 Helena, MT 4.0* 6 U-295 Federal Bldg. Limestone Helena, MT 3.** 1935 11 21 Helena, MT 3.8* 6 U-296 ' rederal Bldg. Limestone Helena, MT 4.** 1935 11 28 Helena, MT 5.0* 6 u-297 rede ra l Sidg. Limestone Helena, MT 5.** 1957 03 22 San rrancisco. 5.3 11 A-015 CoIden Cato Pk. Chert and ShaIe CA San Francisco, CA
- 6. 1966 06 28 Parkrield, CA 5.6 39(7) 8-037 Cholame-Shandon Serpentine and serpentinized Array, Temblor pe ridoti te
- 7. 1970 09 12 Lytte Creek, CA 5.4 19 W-335 Allen Ranch Cranite bedrock Ceda r Sp ri ng s, CA l
l 8. 1971 02 09 San Fernando, 6.4 29 J-142 Array No. 4 Weathered granite bedrock l CA Lake Hughes,CA 9.** 29 J-143 Array No. 9 9 ft or siity and graveIly Lake Hughes, CA sand overlying granite i
gneiss.
i 10.** 24 J-144 Array No.12 5-10 ft or landslide debris Lake Hughes, CA overlying sandstone, con-l glomerate and shale i
11.** 8975 01 12 cape Mendocino, 4.4 16 PC-175 Cape Hendocino Cretaceous Franciscan CA Petrolia, CA volcanic sandstone (g raywache )
12.** 1975 06 07 Cape Mendocino, 5.2 30 PC-675 Cape Mendocino Cretaceous Franciscan CA Petrolia, CA volcanic sandstone (graywacke) 1 or 3 1
,n l \ l,
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TABLE 4-3 (Cont)
EARTHQUAKE RECORDS CONSIDERED Re f. Date Local Epicentra l Record Reco rd ing Site Conditions no. Year & pa_y Ea rthouake Name Maanituda Distance (km) No. Station at Recordina Station 13.** 1975 08 01 Croville, CA 5.7 11 OD-875 Oroville Das Ea rthrill dam
- Crest
- 14. 12 0S-875 Oroville Das Metavolcanic rock Seismograph Sta.
15.** 1975 08 06 Oroville, CA 4.7 8 J-350 Johnson Ranch 10 meters or sediments Af te rshock overlying greenstone 16.** 1975 08 08 Oroville, CA 4.9 8 J-700 Johnson Ranch 10 meters or sediments Aftershock overlying greenstone
- 17. 6 6-700 croville, CA Mesozoic greenstone CDMG No. 6 18.** 1975 09 27 Oroville. CA 4.6 11 J-234 Johnson Ranch 10 meters or sediments Aftersho k overlying greenstone
- 19. 11 8-234 Oroville, CA Mesozoic greenstone CDMG No. 8 20.** 1976 09 11 Friuli, Italy 5.9 6 I-142 Samplago (D) Triassic limestone and Af te rshock dolomite. Installed 260 meters below surface.
- 21. 14 l-139 San Rocco Limestone
- 22. 1976 09 11 Friuli, Italy 5.5 16 1-132 San Rocco Limestone Aftershock l
23.** 10 1-134 Samplago (D) Triassic limestone and I
dolomite. Installed 260 meters below surface.
15 Friuli, Italy 5.0 11 1-159 Samplago (D) Triassic limestone and 24.** 1976 09 dolomite, installed Af te rshock 260 meters below surface.
- 25. 1976 09 15 Friuli, Italy 6.0 19 l-169 San Rocco Limestone l
Af te rshock 2 of 3
1 y--
(
v ) \v)
TABLE 4-3 (Cont)
EARTHQUAKE RECORDS CONSIDERED Ref. Date Local Ep icent ra l Reco rd Record ing Site Conditions Mo. Year g par a Earthouake Name Macnitude Distance (km) No. Station at Recortina Station 26.** 1978 08 13 Sa nta Ba rba ra, 5.1 13 -
UCSB-North Hall Floor slab on caissons CA Coleta, CA extending through 13 ft of soil and founded in siltstone
- 27. 1979 08 06 Coyote Lake, CA 5.9 2 SM-879 Coyote Creek Conglomerate, sandstone and San Ma rtin, CA shale
- 28. 16 G1-879 Citroy No. 1 Sandstone, shale, and chert Cavilan College Water Tower
- 29. 10 . C6-879 Citroy No. 6 Congineer ce, sandstonc and
, San Ysidro, CA sisa le 30.** 1980 01 25 Livermore, CA 5.2-5.8 11 -
L f ve rmo re - Sandstone and shale Morgan Territory (Digitized record riot Pa rk available) 31.** 1982 01 13 New Hampshire 4.7 8 -
Franklin Falls Rock (eg = 4.4) Dam, Rt. abutment
- 32. 1982 03 31 New Brunswick 4.8 4 -
Mitchell Lake Rd. Rock Af te rshock (ab = 5.0)
NOTES:
- Magnitude estimate by Kanamori and Jennings (1978)
- Removed from data base 3 of 3 s
\
si Qj "
-s
- c. -
TABLE 4-4
' ROCK OUTCROP RECORDS
~
USED IN SCALED S0lt RESPONSE A80ALYSIS.
r
' Ep icent ra l .-
Local Scaling Record ing Distance Necord .
Maenitude Factor Station fkal Component 80 0 .
Yea r & Day Earthouake Name 10 31 .Helena, MT 6.0 0.271 CarroII College 6 EW - 8-025 1935 Helena, MT NS 28 Parkfield, CA 5.6 0.446 Cholame-Shandon 39(7) N65W 8-037 1966 06 Array, Teelptor . 525W Lytle Creek, CA 5.4 0.572 Allen Ranch . 19, 505W W-335 1970 09 12 '
585E Cedar Springs, CA San Fernando, CA 6.4 0.165 Array No. 4 29 S69E -J-142 1971 02 09 Lake Hughes, CA S21W-proviite, CA 5.7 0.3T. OroviIIe Den 12 N53W 05-875 1975 08 01 Seismogreph Station N37E Oroville, CA 4.9 1.064 Oroville,'CA 6 S55E 6-700 1975 08 08 N35E Aftershock COMG 100. 6 OroviiIe, CA 4.6 1.452 OroviIte, CA 11 N90W 8-234 1975 09 27 S00E Afte rshock COMG No. 8 Friuli, Italy 5.9 0.307 San Rocco 14 NS I-139 1976 09 11 EW Af te rshock 5.5 0.505 San Rocco 16 NS l-132 1976 09 11 Friuli, Italy EW Af te rshock Friuli, Italy 6.0 0.271 San Rocco 19 NS 1-169 1976 09 15 EW Afte rshock Coyote Lake, CA 5.9 0.307 Coyote Creek .2 250* SM-879 1979 08 06 San Ma rtin, CA 160*
GiIroy No. 1 16 320' G1-879 Gavilan College 230*
Water Tower Giiroy No. 6 . 10 320' G6-879 San Ysidro, CA 230*
4.8 0.750 Mitchell Lake Road 4 118' ML-382 1982 03 31 Mi ramich i . New Brunswick 28*
(ab = 5.0) 1 or 1
TABLE 4-5 ROCK OUTCROP RECOROS AVAILASLE FOR UNSCALED Soll RESPOIISE ANALYSIS Epicenter Local Distance Record .
Recording Year h ggy Name Magnitude fkal No. Commonent Station 1970 09 12 Lytle Creek, CA 5.4 19 W-334 S05W Allen Ranch S85E Ceda r Springs, CA 1975 08 08 Oroville, CA ( Artershock) 4.9 6 6-700 SSSE Oroville, CA N35E CDMG No. 6 1975 09 27 Oroville, CA ( Af tershock) 4.6 11 8-234- M90W oroville,- CA S00E COMG, No. 8 1976 09 11 Friuli, Italy 5.5 16 1-132 MS San Rocco EW 1982 03 31 Mi ramichi, New Brunswick 4.8 4 ML-382 ' 118' Mitchell Lake Road 28' (ab = 5.0) 1 of 1
.[
LAYER UNIT
- SHEAR WAVE l LAYER g THICKNESS WEIGHT VELOCITY * *
(PCF) DEPTH f (FT.) (FT./SEC)
(FTJ- ( FT. )
735 - -
O g 1 10 125 600 725 - -
10 2 10 125 800 715 - - 20 !
3 10 125 950 705 - -
30 4 10 125 950 695 - -' 40 f
5 10 125 1100 ;
685 - -
50 6 10 125 1100 SAND C
675 - -
60 GRAVEL 7 10 125 1100 665 - -
70 8 7.5 136 1200 .
657.5 - -
77.5 !
9 7.5 13 6 1200 650 - -
85
[] 10 10 136 1200 V 640 - -
95 11 10 136 1200 630 - 105 12 to 136 1200 620 - - 11 5 !
BASE HALF 160 5000 ROCK LAYER SPACE ,
NOTES
- UNIT WElGHT FROM BVPS-2 FSAR SECTION 2.5.4.
- w SHEAR WAVE VELOCITY FROM FIGURE 6-2(SWEC,1984)
IN SITU: NATURAL FREOUEN0Y 2.3 Hz r
- t FIGURE 4 - 1 SOIL MODEL O\ BEAVER VALLEY POWER STATION-UNIT 2 STONE C WEBSTER ENGINEERING CORPORATION
70 ,
r~g
.t 60 So -
40 -
E 30 -
20 -
10 -
O ' ' ' '
10-* 10-3 10-2 90-1 g to SHEAR STRAIN (PERCENT)
G 1000Ks (a' ) (PSF)
WHERE G SHEAR MODULUS e'.= MEAN EFFECTIVE SOIL PRESSURE
- a. VARIATION OF SHEAR MODULUS OF SAND WITH STRAIN
,A s Q 35 30 -
h 25 -
9 g 20 -
a:
$ 15 -
t O
10 -
5 -
o 10-4 10-3 10-8 to-' t to SHEAR STRAIN (PERCENT)
- b. VARIATION OF DAMPING RATIO OF SAND WITH STRAIN FIGURE 4-2 STRAIN DEPENDENT SOIL w PARAMETERS BEAVER VALLEY POWER STATION-UNIT 2 STONE E WEBSTER ENGINEERING CORPORATION
$_ i i i a e i i iii i i i i @
() :
'% 3 b m 't o#
5 %o 8
_s o "v'$~ 0 a:
o / -
n 0 / -
e
~ **/n x 8 4,.
t
/ -
/
O r sl>p v c
- .) : .
y - eG 0 _+
- 3 y, z -
- E >-
o o / 2
< - z w
i
, "ci, l
g O e
s i =
! e
- Ng :
~
[' N $ ['-
l
-o
- s ! #
a s ! -
- 'o . \ h Q
+ g, .
vE O'
o*
o I ' ' ' ' '
~
o -
8]
VELOCITY (IN/SEC)
NOTE:
RESPONSE SPECTRA COMPUTED FROM RECORDS LISTED IN TABLE 4-4 FIGURE 4-3 i
HORIZONTAL RESPONSE SPECTRA FROM S0ll RESPONSE ANALYSIS: SCALED
\ BEAVER VALLEY POWER STATION-UNIT 2 STONE E. WEBSTER ENGINEERING CORPOR ATION l
./
SECTION 5 SITE DEPENDENT RESPONSE SPECTRA Two approaches have been used to determine ground surface response spectra, taking into consideration the geology, seismicity and local soil conditions at BVPS-2. They were (1) the site matched response spectra approach, the results of which are discussed in Section 3 and shown in Figure 3-5~, and (2) the soil response analysis approach, the
- results of which are discussed in Section 4 and shown in Figure 4-3.
The site matched and soil- response analyses provide two separate statistical estimates of the site dependent response' spectra.
Advantages. and limitations can be ascribed to each method, and it cannot be stated with certainty which of the two gives the best estimate. Since the two approaches augment one another, to obtain the best estimates of the 50th and 84th percentile site dependent response spectra, the results were combined statistically. The resulting site dependent response spectra for BVPS-2 are shown in Figure 5-1.
5.1 PROCEDURE The statistical analysis procedure used to combine the site matched and soil response analyses results is fully described in Appendix 6 and briefly summarized below.
O The response spectra pseudo-velocities are log-normally distributed.
Q The best estimate of the 50th percentile site dependent response spectrum was determined as the linear combination of the results of the two approaches according to the expressions:
MEANLOGV =Wsm(MEANLOGV sm-) + Wsr(MEANLOGVsr)
(EQ 5-la)
MEDIANV = 10 MEANLOGV (in/sec) (EQ 5-lb) where:
W ,W = weighting factors for the site matched analysis sm sr ~ and the soil response analysis, respectively The weighting factors were chosen to minimize the variance of the estimate of the mean of the underlying distribution. Expressions for the' weighting factors'are provided in Appendix 6.
The calculations described by Equation 5-1 were carried out for each frequency at which the two sets of spectra had been evaluated.
The best estimate of the variance of the logu Pseudo-velocities was
' determined assuming that the variances of the individual data sets were chi-square distributed. This resulted in a combination of the individual variances that was weighted according to the number of 5-1
observations (earthquake records) . in each data set. The governing equation was:
= 0.3864 (VARLOGV,,) + 0.6136 (VARLOGVsr)
VARLOGV (EQ 5-2)
.It then follows that the 84th percentile value of the pseudo-velocities is calculated for each frequency according to the equations:-
MSDLOGV = MEANLOGV + (VARLOGV) 1/2 (EQ 5-3a)
MSDV = 10 MSDLOGV (in/sec) (EQ 5-?'s) 5.2 RESULTS The '50th and the 84th percentile site dependent response spectra for 5 percent damping are plotted in Figure 5-1. The 50th percentile response spectrum falls well below the BVPS-2 design response
. spectrum. The 84th percentile response spectrum closely matches the design spectrum above 6'Hz and falls below it for all other frequencies, sometimes substantially.
Section 6 _ demonstrates that the annual probability of exceeding the
.-50th percentile site dependent response spectrum is about 10 4 and is about 10 5 for the 84th percentile spectrum. The annual probability associated with the 50th percentile spectrum is comparable to values usually accepted for the SSE; the probability for the 84th percentile is substantially lower. The BVPS-2 design response spectrum,
.p therefore, has an annual probability of exceedence that is very low
- and in the frequency range of interest to BVPS-2 plant structures
-(2-10 Hz)'is about 10 s, 5-2
1 0
0
! .. . . - - ~ 0 1
0 i i _
O i
a f -f c i
i 2
0 i
a 4
e, +
9 o i 0
5 0
a ,
p 5
0 i A ,
0 1
0 e x / ,
01 i i i i a
)
2 ,
5Z
) 0 i
Q O H C G s\
(
E i N ,
S l Y
( P C .
D M , N O A E I D U R Q -
E % E P5 0
i Q m 5 ,
R F
O 1
i
[ /, ,
1 e
i 2 S
/ E
/
e
_ P L e ,-
5 2 i v I T , 0
$(
N
%,#'c ,
/
E i
C h
t R O 0E
_ x 5P ,
K E/
L ,
5 i TI c, N E
h C R
/s#c t
4E 8P 1
. . . - _ _ ~
0 1
0
- soy E i
m A m5$a O m m
m A * $-
j p p =o Y$he y m 8hch w mh9 Ee
SECTION 6 f-PROBABILISTIC ANALYSIS
\(
- \- / ' Exceeding a given response spectrum at BVPS-2 depends on the interaction of several factors - earthquake magnitude, epicentral
' distance, attenuation characteristics of the region, and the time
- history of motion. An earthquake of sufficient size must occur near enough -to the ' site so that the attenuated motions will cause a significant ground shaking at.the site. The resulting time- history -
(of motion at-the' site and the corresponding set of response spectra are, of' course, unique for each earthquake. . All_ of these factors have uncertainty associated with their' potential effects at the site, which suggests a probabilistic : approach to evaluating response spectra.
~Accordingly, two related probabilistic analyses were performed. .The first. consisted of three conventional seismic hazard- analyses performed using two tectonic province models and a seismic source zone model. The analyses considered the contribution.to the seismic hazard at. BVPS-2 due to those parts of the United States and Canada lying east of 84'W, north of 34'N, and south of 47*N as well as . local sourcesL at New Madrid, MO: Charleston,. SC; Anna, OH; La Halbaie, PQ;
.and the Wabash Valley. It led to~ a general understanding of -the
. seismic hazard at the site and to the conclusion that almost all-of the. hazard is contributed by the Appalachian Plateau tectonic province -or by background seismicity for the. seismic zone model.
Based upon the results of the conventional seismic hazard analysis, a
/N more detailed examination of the region near the site was made which
\ :resulted in an estimate of the annual probability of exceeding the 50th and 84th percentile site dependent response spectra.
6.lESeismic Hazard Analysis The annual probability of exceeding a given level of shaking at a site,-more simply, the annual seismic hazard, is usually calculated by methods based on the work of Cornell (1968), and implemented in the widely used -program developed by McGuire (1976). In .this L approach, earthquakes are allowed to occur at random throughout the-different zones of seismicity and are governed by the annual rate of occurrence of events equal to or greater than a given magnitude (the activity rate) and by the relation between magnitude and number of
, events (the recurrence relation). Their effects are evaluated at the site _according to an attenuation relation. Thus, a seismic. hazard
-analysis requires: (a) establishing a geometric pattern of seismic sources; (b) for each source, determining the activity rate, the recurrence relation, and upper bound limits on earthquake size; and (c) _ choosing an appropriate attenuation relation. The annual probability of exceeding various levels of shaking at thu site is then computed.
S i
N 6-1
~6.1.1 Contributions of Tectonic Provinces and Seismic Source Zones The2 historic. earthquake catalogue that was used for this analysis 4
O\ Lcovered.the period from -1871 to 1976.
processed The catalogue had been to' retain all events of epicentral intensity greater than.
or equal to V (MM). A map. of ' epicentral locations is' shown in Figure 6-1.
For lthe. present case, two approaches.were used to establish seismic
,. sources. The first' method used the. tectonic provinces and concentrated, local. seismic sources shown in Figure 6-2. The local sources-include New Madrid, Missouri; Anna, Ohio; Charleston, SC; the
'Wabash valley.carea; and the La Malbaie. area in Quebec. Surrounding the site is the.-Appalachian Plateau tectonic province, which is distinguished from the Central Stable Region and the Northern Valley and Ridge tectonic. province. The precise locations of the boundaries between the provinces are not significant factors in the analysis.
The western bot.ndary of the Appalachian Plateau tectonic province shown Ein Figure =6-2 is located somewhat to the west of that shown in Figure 6-5; this has the effect of including within the Appalachian Plateau tectonic province .the 1926 intensity VI-VII(MM) event in southeastern Ohio. Several ' earthquakes in the . historical record occurred near a tectonic province beundary, so that they could have occurred in either province. 'The alternative choices resulted in two distributions of historic activity.in the provinces, which are called Provinces I and Provinces II in the subsequent discussion.
. fN The 'second method is based on 'the work done on seismic -source zones by Chiburis (1979) and expanded with data developed by Nuttli (1979) and Bollinger (1975). Chiburis (1979) identified sources of seismic
~ activity by applying pattern recognition techniques to the historic seismic . record. This led to a set of seismic source zones and an
-overall background seismic activity that accounts for seismicity not included. in specific zones. Figure 6-3 shows the configuration of the seismic source zones used in the analysis. The tectonic
' provinces and seismic source zones used in this analysis are the same as those presented by Acharya, Lucks, and Christian (1984), from which Figures 6-1, 6-2 and 6-3 were adapted.
All of the events in the earthquake catalogue were described in terms of body-wave magnitude, and annual activity rates were evaluated for each . province for time intervals before 1976 ranging from 10 to 100 years. The most reasonable values of average activity were chosen for each tectonic province. The recurrence relation predicting the number N of events per year equal to or greater than magnitude ab is
.of the forms 1 Log N = a-bab (Eg 6-1)
The parameters a and b are empirical a describes the activity rate
'and b is-the slope of the recurrence relation. For this analysis, b was selected to be 0.9.
6-2
i f
The1 following attenuation relaticn, proposed by Hermann and Nuttli
.(1984), was.used with'a standard deviation of 0.6 to. account for
' /'~Y uncertainty kJ log ah~ = 0.57 + 0.50 mb - 0.83 Log.(R2 + ha)d2 - 0.00069 R + E with o g = 0.6- (Eq. 6-2) 6.'l.2 Seismic Hazard at BVPS-2'
_ Figure. 6-4 and Table 6-1 summarize the results for all three models.
The annual probability of equaling or exceeding a horizontal ground surface . acceleration' greater than or equal to 0.125g, which is the -
zero period acceleration for.;the SSE, ranges from 1.32x10-4 to
- 2.47x10-4..
Table 6-1 shows that the overwhelmingly major portion of the seismic hazard at BVPS-2 is contributed by the Appalachian Plateau tectonic province: (for Provinces DI /and II) or background seismicity (for seismic zones). One can see in the computer output that it is..the
-portion' of ,the Appalachian Plateau tectonic province or background zone immediately surrounding the site that. contributes to the seismic hazard.- For ah. equal .to or greater than 0.125g, these contribute
-between 92 percent and 96 percent _ of the total : seismic hazard.
Almost: ~ all of the remaining seismic hazard derives from the local
-source near Anna, Ohio.
The- activity rates and recurrence relations 'idclude' the effects of
. s both shallow and -normal focal depth earthquakes. Since shallow earthquakes ~ are typically felt over much smaller areas than normal focal depth earthquakes'of similar magnitudes, the attenuation of the
- shallow . events must. be more severe. ~ consequently, the computed seismic hazard.would be reduced by distinguishing between the two types; of events. Since this was not done in this analysis, the L. results include some conservatism.
6.1.3 Summary l
b A. seismic hazard ' analysis performed using conventional procedures results in an annual seismic hazard of about 10-4 for a horizontal ground surface acceleration, ah, equal to or greater than 0.125g,
-which corresponds to the SSE. The annual seismic hazard is slightly
, larger for ah . equal to or greater than about 0.12g, which is the 84th
! . percentile value at frequencies above 50 Hz from Figure 5-1. This b hazard is very strongly dominated by the region around the site,.and l' therefore, a. refinement of the hazard analysis should emphasize this
!; region. In addition, the shapes of response spectra assoc'ated with this_ local activity can be studied by examining historical strong motion recordings..
l }6.2 Probability of Exceeding Response Spectra 1The conventional. analysis described in the preceding section showed that the seismic hazard at BVPS-2 is almost completely dominated by 6-3 p s
- ...-...--o _ _ _ , . . _ . . . . - . . _ . - . _ . . . _ - _ -
- m
-the -portion of t'he Appalachian Plateau tectonic province around the site. . Consequently, the'second analysis developed a more detailed M ; description of'the-recurrence relation in that region. .Also, in the
?
site matched response spectra analysis and in the . soil response analysis,~ all .of- the~ earthquake records' used to compute ground
- surface response spectra were recorded within 29 km of the epicenters of the frespective earthquakes. . Therefore, the second probabilistic
- analysis ' accounted for the occurrence of an event ---within 29 km of-
- BVPS-2.. This approach incorporates the effects of attenuation in that the record:.cthemselves reflect the effects of attenuation. The earthquake records.also include the effects of near' field-motions.
6.2.1 Metho'd ology-The probabilities were computed from the product of the. yearly probability of~the design or greater earthquake occurring anywhere in the Appalachian Plateau tectonic province, the conditional probability of its occurring within a 29 km radius of the site .given=
that it.-occurs in the. province, and the percentile probability-associated with the site dependent response spectra.
.The probability' that. the site dependent response spectrum would be
~
exceeded was determined from the joint and conditional probability equation:
P(A 2 &A)=
3 P(A2 ) P(Aa ) (Eq 6-3)
=. P(Ag ) P(A2 lA1 ) P(A3 )
O where V . .
_ A2 and As are'stochastically independent-P(A 2 &A)=
a Probability of an event of mb 2 4.75 occurring.
within 29 km of the BVPS-2 site and causing .a response' spectrum exceeding a given percentile site dependent response spectrum P(Ag ) = probability of an event of mb 2 4.75 occurring in the. Appalachian Plateau tectonic province
.P(A2 ) = Probability of an event of mb 2 4.75 occurring within 29 km of BVPS-2 site P(A2 lA ) g
= conditional probability of an event of mb 2 4.75-occurring within 29 km of BVPS-2 given that the event occurs within the Appalachian Plateau tectonic province' P(A3 )' = probability that an earthquake with mb 2 4.75 occurring within 29 km of a site with site
+,
characteristics similar to BVPS-2 produces a response spectrum that exceeds a given percentile site dependent response spectrum.
6-4
6.2.1.1 Recurrence Interval for Design Earthquake As discussed in Section 2.1, the SSE for BVPS-2 has been estimated to
) be equivalent to an event with a body-wave magnitude of 4.75. P(A t),
the annual probability of exceeding the SSE within the Appalachian Plateau tectonic province, was determined from the observed historical seismicity of the province within 200 miles of the site.
A recurrence relation that predicts the numbers of events, N, with value is similar to body-wave Equation 6-1. magnitude, Nuttli mb(,
1974)greater thana arecurrence presented given relation for the Mississippi Valley region. His relation, however, defines N as the annual number of events having magnitudes within a given interval, rather than as the number of events having magnitudes equal to or greater than a given value. When his data were reexamined to obtain a recurrence relation in which the latter definition of N was used, the parameter b in Equation 6-1 was found to be 1.03. This value was used in subsequent calculations since the intent was to determine the probability of exceeding a given level of shaking, namely, mb2 4.75.
Figure 6-5 shows the historical earthquake epicenters and tectonic province boundaries within 200 miles of the site (SWEC, 1984a). From the earthquake catalog for BVPS-2 presented in SWEC (1984b), 50 events have occurred in the portion of the Appalachian Plateau tectonic province within 200 miles of the site. This subset of events from the BVPS-2 earthquake catalog is provided in Table 6-2.
Statistical evaluation of the data in Table 6-2 was performed using the methods described by Nuttli (1974). Two magnitude limits were
) considered, m3 2 2.9 and my 2 3.4, as being the most likely to be
(/ completely reported over a limited time period in an area of limited sesimicity. For those events in Table 6-2 for which magnitudes were not reported, they were estimated from the epicentral intensities.
The annual numbers of events, N, for m 2 2.9 and for mb 2 3.4 were found to be 0.36 and 0.27, respectively.b From these data and the recurrence relation given by Equation 6-1 with b equal to 1.03, the following estimates of the annual number of occurrences of events having an m 2 4.75 were obtained:
b if N = 0.36 for mb2 2.9, then N = 0.0045 for mbt 4.75 if N = 0.27 for g2 3.4, then N = 0.0110 for m b2 4.75 Therefore, a high estimate of P(A 1) is 0.0110 and a low estimate is 0.0045. Alternatively, the seismicity data for 100 years in the Appalachian Plateau tectonic province within 200 miles of the site give the recurrence relation plot shown in Figure 6-6. This yields an estimated P(Ag ) of 0.006.
The inclusion or exclusion of the 1926 event in southeastern Ohio has little effect on these numbers.
(gV
)
6-5
6.2.1.2 Conditional. Probability of Design Earthquake Within 29 km of the Site g
y/ The probability of an earthquake with an mb2 4.75 occurring within a 29 km radius of the BVPS-2 site, given that the event has occurred in the Appalachian Plateau tectonic province,.is the ratio of the area
~
of a circle with a radius of 29 km to the area of the Appalachian Plateau tectonic province within 200 miles of the site. The choice of a 29 km radius around the BVPS-2 site was based on the fact that all of the earthquake records used for the scaled site matched analyses (Table 3-1) and the scaled soil response analyses (Table 4-
- 4) were recorded at epicentral distances ranging from approximately 4 km to approximately 29 km. Determining the probability in this manner implicitly assumes that the probability distribution for an earthquake occurring anywhere within the Appalachian Plateau tectonic province is uniform. This is a. reasonable assumption based on the geology of a tectonic province model possessing no unique
- seismological features that would be more or less preferential for
! earthquake hypocenters.
The area of a circle with a 29 km radius is 2642.1 sq km. From Figure 6-5, the area of the Appalachian Plateau tectonic province within 200 miles-of the site is 136,863 sq km. Therefore:
P(A 2 IA 1 ) = 2642.1/136,863 = 0.0193 6.2.1.3 Probability of Exceeding Site Dependent Respense Spectra
-U
[] The site dependent response spect.ra were calculated assuming that the individual response spectrum pseudo-velocity values for a given frequency were log-normally dis >.ributed; i.e., that the logarithm of the pseudo-velocities were norma.'ly distributed. For this case, the probability of exceeding the median value is 0.5. Therefore, the probability of an earthquake with an mb 2 4.75 occurring within 29 km of a site similar to BVPS-2 wLich produces a respo'nse spectrum that exceeds the 50th percentile site dependent response spectrum is:
P(A3 ) = 0.5 (For 50th percentile)
Likewise, the probability of an earthquake with an mb 2 4.75
- occurring within 29 km of a . site similar to BVPS-2 which produces a
' response spectrum that exceeds the 84th percentile site dependent response spectrum is:
P(A3 ) = 0.16 (For 84th percentile) 6.2.2 Results The probability that an earthqual.c with an mb 2 4.75 vill occur within the Appalachian Plateau tectonic province and within 29 km of the site and will produce a response spectrum greater than the site dependent response spectrum was determined as the product of the im 6-6
LindepIndent cnd cenditienni probabilitiss previcusly discussed. From equation 6-2, for the.50th percentile. response spectrum:
L P(Aa T& Aa) = (0.0045 or 0.0110) (0.0193) (0.5)
This' gives lan' annual-probability of exceedence between 4.4x10 and 1.1-x 10-4 ^For the 84th percentile response spectrum:
P(Az & A3 ) = (0.0045'or 0.0110) (0.0193) (0.16)
'This gives an annual probability of exceedence between 1.4x10-5 and 3.4x10-s; As described in Section 6.2.1, the value of P(A 1) estimated directly from the recurrence relation within 200 miles of the site is 0.006.
This giveslan annual probability of exceedence of 5.8 x 10-5 for the mean ! response--spectrum and 1.9 x 10-5 for the 84th percentile x
' spectrum.
These calculations have not included the contributions of events with ab <4.75 to the probability of exceeding _ the various response spectra. Approximate extrapolation of the present results using Herrmann and Nuttli's relation (Equation 6-2) indicates that the smaller earthquakes may increase the computed annual probability of exceeding the- response spectra to about 2.3x10-4 for the
.50th percentile spectrum and. 5.3x10-s for the 84th percentile
~ spectrum.
- '% 6.3 Discussion The seismic hazard ' analysis led to the conclusion that the seismic
. hazard at;the site is overwhelmingly dominated by the seismicity of the Appalachian - Plateau tectonic province. A 'more detailed examination of that province provides an estimate for the annual 1
probability ' of an earthquake with a body-wave magnitude greater than or equal to.4.75 occurring within 29 km of BVPS-2. The response spectra for earthquakes within this radius, normalized to a body-wave
-magnitude of 4.75, provide statistical estimates'of the distribution of response spectra.- These, combined with the computed annual probability for' the earthquakes, give an annual probability of
> exceeding the 50th percentile response spectrum of between 4.4x10-s and 12.0x10-4 The _ annual- probability of exceeding the 84th
< percentile response spectrum is 1.4x10 5 to 4.4x10 5
- A . sigaificant ' conclusion is that the 50th percentile response spectrum computed from a suite of actual accelerograms has an annual probability of exceedence that is lower than values usually accepted for the SSE and, therefore, represents an acceptable degree of conservatism. The 84th percentile response spectrum has an annual
- probability of exceedence that is very much lower.
6-7
TABLE 6-1 SEISMIC HAZARD ANALYSIS For ah = 0.125g Annual Contribution Case- Exceedence of Appalachian No. Description Probability Province A Tectonic Province'I 1.68x10-4 1.58x10-4 g24.0 (94%)
A-2 Tectonic Province II 2.47x10-4 2.37x10-4 g24.0 (96%)
B-1 Seismic Zones 1.32x10-4 1.21x10-4 g24.0 (92%)
O O 1 of 1
TA8LE 6-2 EARTHQUAKES WITHIN 200 MILES OF THE SITE AND WITHIN THE APPALACHIAN PLATEAU TECTONIC PROVINCE Felt Date Origin La ti tude Longitude Intensity Depth Area Yea r Month pay Time f'N1 "I W1 fMMI fkm) Maanitude fx108 mia1 Location 1823 05 30 41.5 81.0 IV 3.8 1824 07 15 1620 39.7 80.5 IV 1836 07 08 41.5 81.7 IV 3.8 1857 03 01 41.7 ' 81.2 IV-V 4.0 1857 12 10 2200 37.8 80.4 1857 12 11 0300 37.8 80.5 1858 04 16 1200 41.7 81.3 IV 3.8 1867 01 13 41.5 81.7 Ill 3.4 1872 07 23 41.4 82.1 IV 3.8 1873 08 17 1400 41.2 80.5 Ill Sha ron, PA 1885 01 18 1030 41.1 81.4 (IV) (3.8) 1885 01 18 1130 41.3 81.1 Ill 3.4 1885 08 15 0505 41.3 81.1 Il 3.2 1885 09 26 2030 40.3 80.1 til
~
1898 10 24 41.5 81.7 I I l-IV . 3.6 1900 04 09 1400 41.4 81.8 Vi* 4.7 (3.8) 1902 0 14 0700 40.3 81.4 IV-V 4.0 1906 04 20 1730 41.5 81.7 (Ill) (3.4) 1906 04 20 1830 41.5 81.7 IV 3.8 1906 06 27 1210 40.4 81.6 V* 4.2 (3.4) 0.4 1906 06 27 2210 41.4 81.6 V IV Wi l l iamspo rt, PA 1907 01 10 1000 41.2 77.1 ,
1 of 3
e -
.e U %j TABLE 6-2 (Cont)
Felt Date Origin La ti tude itude LongW1 intensity Depth Area Yesr Month Day Time f'N ri MM) fkm) Maanitude fx10 ,ga1 Location 1907 04 12 41.5 81.7 Ill 3.0 1927 10 29 40.9 81.2 V 4.2 1928 09 09 2100 41.5 82.0 V 4.2 1.5' 1929 09 17 1900 41.5 81.5 Ill 3.0 1932 01 22 41.1 81.5 V* 4.2 (3.6) 1934 10 29 2007 42.0 80.2 V Erie, PA 1934 11 05 2000 41.8 80.3 Ill 07 13 40.5 78.5 VI B la i r Co. , PA 1935 1935 11 01 0330 38.9 79.9 V 1935 11 01 2030 39.9 79.9 V G reenvi l le, PA 1936 08 26 0900 41.4 80.4 Ill V-VI Blair Co., PA 1938 07 15 2245 40.7 78.4 1940 05 31 1700 41.1 81.5 11 3.0 1951 12 03 0200 41.6 81.4 IV 3.8 0.1 1951 12 03 0702 41.6 81.4 (IV) (3.2) (0.1) 1951 12 07 41.6 81.4 ll 3.0 1951 12 21 2100 41.6 81.5 11 12 22 0400 41.6 81.4 11 3.0 1951 1955 05 26 1809 41.5 81.7 V (IV-V)* 3.8 (3.6) 1955 06 29 0116 41.5 81.7 V (iv)* 3.8 (3.6) 01 2247 41.5 81.7 IV-V 4.0 1958 05 40.1 79.8 3.3 Southwestern PA 1965 10 08 0217 1966 09 28 2059 39.3 80.4 IV (3.8) 1972 09 12 1715 39.7 79.9 2 of 3
- [k.-
U TABLE 6-2 (Cont)
Felt Date Origin La t i tude - . Longitude Intensity Depth Area yngr Month gag Time f*N ~f W1 MM) ( km) Maonitude fx10 agal Location 1974 10 10 2146 42.3 77.7 2.2 Ho rne l l, NY-1974 10 20 1514- 39.1- 81.6' V 3.4 1975 08 30- 0614 42.7 78.1 2.1 S of Wa rsaw, . NY 1978 10 26 2154 42.7 77.8 6- 2.6 Mount Morris, NY NOTES:
Table is condensed from the earthquake catalog provided in the BVPS-2 FSAR (SWEC, 1984a)
Data in parentheses taken from Nuttli (1981)
- Indicates shallow earthquakes per Nuttli (1981) 3 of 3
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SECTION 7 (v CONCLUSIONS The._results of the analyses presented clearly demonstrate that the BVPS-2 horizontal and . vertical design response spectra are appropriate.
SWEC (1984) presented data showing that the use of two-thirds as the ratio of vertical to horizontal response spectra is consistent with available earthquake data from _ the United. States and Japan. This report shows that two-thirds is conservative at all frequencies.
-The BVPS-2 horizontal design response spectrum for 5-percent structural damping compares favorably with site dependent response spectra computed from the combined results of two different state-of-the-art procedures. A probabilistic analysis .also shows that the annual probability of exceeding the BVPS-2 design response spectrum is very low and that it has an acceptable degree of conservatism.
O 7-1
F SECTION 8 s REFERENCES l
)
m
.Acharya, H.K.; Lucks, A.S.; and Christian, J.T. Seismic Hazard in the Northeastern United States. Soil Dynamics and Earthquake Engineering, Vol. 3, No. 1, 1984.
Bollinger, G.A. Catalogue of Earthquake Activity in the Southeastern United States. Virginia Polytechnic Institute, 1975.
Brady, A.G.; Mork, P.N.; and Fletcher, J.P. Processed Accelerograms from Monticello Dam, Jenkinsville, South Carolina, 27 August 1978 and from Later Shocks. U.S. Geological Survey Open File Report 81-448, March, 1981.
Chang, F.K. Analysis of Strong Motion Data from the New Hampshire Earthquake of January 18, 1982. Prepared for the U.S. Nuclear Regulatory Commission. NUREG/CR-3327, 1983.
Chiburis, E.C. Earthquake Catalogue for the Northeastern U.S. and Southeastern Canada. Personal communication (unpublished), 1979.
Chung, D.H. and Bernreuter, D.L. Regional Relationships Among Earthquake Magnitude Scales. Lawrence Livermore Laboratory Report 52745. Prepared for U.S. Nuclear Regulatory Commission, NUREG/CR-1457, 1980.
I_,, )
( ,/ Cornell, C.A. Engineering Seismic Risk Analysis. Bulletin of the seismological Society of America, Vol. 58, 1968.
Hermann, R.B. and Nuttli, 0.W. Scaling and Attenuation Relations for Strong Ground Motion in Eastern North America. Proceedings of the 8th World Conference on Earthquake Engineering, San Francisco, July, 1984.
Idriss, I.M. Personal Communication with W. Savage of Woodward-Clyde Consultants. November, 1984.
McGuire, R. Fortran Computer Program for Seismic Risk Analysis.
U.S. Geological Survey Open File Report 76-67, 1976.
McGuire, R. . Testimony about V.C. Summer Nuclear Station. Atomic Safety and Licensing Board Hearings. Columbia, SC. Docket 50-3957, 1982.
Nuttli, 0.W. Magnitude Recurrence Relations for Mississippi Valley Earthquakes. Bulletin of the Seismological Society of America, Vol. 64, No. 4, 1974.
8-1
Nuttli, 0.W. Seismicity of the Central United States. lIn: Geology in the Siting of Nuclear Power Plants. Reviews-in Engineering Geology, d Vol.'IV. Geological 2 Society of America, 1979.
Nuttli, 0.W. Instrumental Data. In: Nuttli,'O.W.; Rodriquez, R. and Herrmann, R.B.. Strong Ground Motion Studies for South Carolina Earthquakes.- Prepared- for U.S. Nuclear Regulatory Commission.
NUREG/CR-3755,. April, 1984.
Nuttli,. 0.W.- Personal Communication with H. Acharya of SWEC.
October 11, 1984a.
Nuttli, .0.W., and Brill,.K.G., Jr. Earthquake Source' Zones in the
-Central United States Determined from Historical Seismicity. In: An Approach to Seismic Zonation for Siting Nuclear Electric Power Generating Facilities in the Eastern United States. U.S. Nuclear Regulatory Commission Report, NUREG/CR-1577, pp.98-143, 1981.
Nuttli,. O.W. and Herrmann, R.B. State-of-the-Art for Assessing.
Earthquake Hazards.in the United States: Credible Earthquakes for the Central United States. Miscellaneous Paper S-73-1, Report No. 12.
U.S. Army Engineers, Waterways Experiment Station, Vicksburg, MI.,
1978.
Nuttli, 0 W. and. Hermann, R.B. Ground Motion of Mississippi Valley Earthquakes. Journal of Technical Topics in Civil Engineering,
'Vol. 110, No.'1. ASCE. May, 1984.
O Schnabel, P.B.; Lysmer, J.; and Seed, H.B. SHAKE: A Computer Program for Earthquake Response Analysis of Horizontally. Layered Sites, Report EERC-72-12. University of California at Berkeley, 1972.
Seed, H.B. and Idriss, I.M. Soil Moduli and Damping Factors for Dynamic Response Analysis. Report EERC-70-10. College of Engineering, University of California at. Berkeley, 1970.
Shannon and Wilson, Inc. and Agbabian Associates. (SW-AA).
Geotechnical Data from Accelerograph Stations Investigated During _the Period 1975-1979, Summary Report. Prepared for U.S. Nuclear
' Regulatory Commission. . NUREG/CR-1643, 1980.
Stone and Webster Engineering Corporation (SWEC). Report on the Soil Densification Program, Beaver Valley Power Station -
Unit 2.
Prepared for Duquesne Light Company, Pittsburgh, PA., 1976.
Stone and. Webster Engineering Corporation (SWEC). Final Safety Analysis Report. Beaver Valley Power Station - Unit 2,1983 Stone and Webster Engineering Corporation (SWEC). Seismic Design Response Spectra, Beaver Valley Power Station - Unit 2. Prepared for Duquesne Light Company, Pittsburgh, PA., June, 1984.
8-2
L j'; ,
!. Trifunac, M.D. Stress estimates for the San Fernando, California i ' Earthquake of February 9, 1971: Main Event and Thirteen Aftershocks.
I Bulletin of the Seismological Society of America, Vol. 62, No. 3, 1972. ,
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APPENDIX 1 ;
NUCLEAR REGULATORY COMMISSION j i
RESPONSE SPECTRA ACTION ITEMS i i
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NUCLEAR REGULATORY COMMISSION RESPONSE SPECTRA ACTION ITEMS
,-~g The following action items were identified by the Nuclear Regulatory
- ('N') -Commission (NRC) during its review of the Stone & Webster Engineering Corporation report discussing the reevaluation of the BVPS-2 horizontal and vertical design response spectra (SWEC, 1984).
From the August 16, 1984 notes of conference prepared by NRC:
1.0 Improve the site-specific rock spectrum by including additional strong motion rock records.
2.0 New attenuation laws are now available which differentiate between high magnitude and low magnitude earthquakes. This allows magnitude-specific amplification factors to be calculated. The applicant should compare these new data with those previously presented. (
Reference:
" Strong Ground Motion Studies for South Carolina Earthquakes" by Nuttli, Rodriguez and Hermann, 1984).
3.0 Attempt to show that the soil records used are representative of the conditions at the BVPS-2 site by varying the rock properties while using a mean soil profile.
From the October 4, 1984 telephone conversation with the NRC:
4.0 Appalachian Plateau tectonic boundary and shallow earthquakes
{v} 4.1 The western boundary of the Appalachian Plateau tectonic province (as revised in the FSAR Amendment 4, Figure 2.5.1-5) was not defined well enough to exclude the November 1926 intensity VI - VII (MM) earthquake in southeastern Ohio from the Appalachian Plateau tectonic province.
4.2 Provide a more detailed discu:sion regarding the energy released by shallow earthquakes and the resulting damage effects on the BVPS-2 plant structures.
5.0 Vertical Response Spectra Vertical. response spectra should be computed from the suite of site matched ground surface records, and the mean vertical response spectrum should be compared with the mean horizontal spectrum. This is to justify the use of 2/3 as the ratio of the vertical to horizontal acceleration.
y
[) Al-1
O APPENDIX 2 SHALLOW EARTHQUAKES I
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SHALLOW EARTHQUAKES
/~' Earthquakes with shallow ' focal' depths, having lower magnitudes and
-ks _,N
/ . smaller felt areas than other earthquakes with the same epicentral intensity, have occurred ~in the central United States. This type of earthquake has occurred within 200 miles of. the BVPS-2 site and within the Appalachian Plateau-tectonic province in which the site is located. .Similar earthquakes could occur in the future in the vicinity of _BVPS-2, but the occurrence of this type of earthquake is
' infrequent and the resulting ground motions are not expected 'to
.present a seismic hazard to the BVPS-2 plant structures.
.The purpose of this appendix is to discuss the probable occurrence of shallow earthquakes near the BVPS-2 site, the energy release of these-
-events and the resulting effects on plant structures.
Nuttli- and Brill (1981) have identified a special class of earthquakes that ' occur in the central United States. These earthquakes have lower magnitudes and smaller felt areas than other
-earthquakes with the same epicentral intensity. An example of this type 'of event is- the 1965 Illinois earthquake with an epicentral intensity of VII (MN), a radius of perceptibility of about 25 km and a computed magnitude of 3.8. By comparison, a more normal event such
-as the 1968 Illinois earthquake, which also had an epicentral intensity of VII (MM); had a radius of perceptibility of 500 km and a computed magnitude of 5.5. Theoretical studies by Herrman and Nuttli (1975) .showed that the anomalous characteristics of this class of earthquakes are the result of shallow (<3 km) focal depths.
[)
' \ s/
Earthquakes with focal depths of less than 3 km strongly excite fundamental mode, high frequency surface waves that attenuate rapidly with distance, while these same waves are not excited by earthquakes with greater focal depths.
Nuttli and Brill (1981) thoroughly examined historical earthquakes'in-the central United States and identified 59 events a's having shallow focal depths. Thirty-five of these events occurred in the principle earthquake zones previously identified by Nuttli (1979), and twenty-four did not. The distribution of shallow earthquakes in the central United States is,- therefore, similar to the distribution of normal focal depth' earthquakes, in that a significant fraction occur outside the principle seismic zones and might occur anywhere in the central United States.
The rate of occurrence of shallow earthquakes is extremely low
-(Nuttli, 1982). Out of about 1,200 earthquakes in the central United States with m 2 3.0 (felt events), only 59 have been identified as b
. shallow events. Similarly, the earthquake catalog for BVPS-2 (FSAR Table 2.5.2-2) lists about 230 events within 200 miles of the site, but only 10 of these are considered to have been shallow events (Table A2-1).
BVPS-2 is located in the Appalachian Plateau tectonic province, an area of low seismicity, with very few normal focal depth earthquakes O A2-1
c
% L reported in the1 vicinity of the site (Figure 2-1). The number of
- . ' shallow earthquakes presumed to have occurred within the Appalachian GL Plateau tectonic province is extremely low (Figure A2-1). Shallow
- h earthquakes occurring in other tectonic provinces near the site would not - be felt'. at..the site because of the very small felt areas for these events.
Historical ' seismicity suggests an average rate of'approximately one shallow earthquake every forty : years -in the Appalachian Plateau
'tectonicJprovince. Nuttli and Brill- (1981) showed that shallow
! earthquakes in the' central. United States are not felt- beyond 20 to
.25 km from~ the epicenter, so although a shallow earthquake could
. occur within -the Appalachian Plateau tectonic province, the likelihood of it being felt at the BVPS-2 site is extremely low.
The highest intensity shallow earthquake that occurred in the Appalachian' Plateau. tectonic province was an intensity VI (MM) event, occurring in 1900, with a body-wave magnitude of 3.8. An intensity
' VI-VII (MM) shallow earthquake occurred in southeastern Ohio in 1926.
~
~This. earthquake had a body-wave magnitude of 3.4 and a felt-area of' only'350 sq mi, which suggests that is was not felt beyond about L10 miles from the epicenter. This earthquake occurred within the
. Central Stable Region tectonic province, but close to the common boundary with' the Appalachian Plateau tectonic province. To be conservative,.the effect on an intensity VI-VII (MM) earthquake, with a magnitude of 3.B, occurring near the BVPS-2 site has been
-evaluated.
The entire data base- for the eastern United States that might be A used for the prediction of ground motion from shallow earthquakes is the ^ strong motion records for four earthquakes- near Monticello reservoir in South Carolina. The first of these earthquakes occurred in August 1978. . This earthquake had a body-wave magnitude of 2.8 and
.was assigned an epicentral intensity of V (MM). The accelerograph recorded a peak ground--acceleration of 0.25 g 'and a duration of one-half second' of strong ground shaking. This was the highest value of peak ground acceleration recorded in the eastern _ United States up to that time. . The earthquake of October 1979 in this vicinity however produced records with peak ground acceleration of 0.35 g and a duration of one second. The magnitude of this earthquake was also
'2.8.
- Analysis of these strong motion records indicated that the peak accelerations occu.rr,ed as high frequency spikes of short duration and therefore did not represent a significant energy input to typical power plant structures (McGuire, 1982). Brady et al (1981) found the records 'had- frequencies as high as 25 and 30 Hz. One component of the record for the August, 1978 earthquake had.the peak acceleration
-at a frequency of 33 Hz, and an aftershock of this earthquake recorded the peak acceleration at 40 Hz. Furtherr.: ore , these strong motion records may be inappropriate to characterize ground motion from shallow earthquakes for design purposes because soil amplification studies showed that the sapprolite underlying the O A2-2
accelerograph amplified the ground motion at certain frequencies
-(McGuire, 1982). .Also, field evidence suggests that the interaction of lof . soil; and the concrete accelerograph foundation produced
} significant amplification of high frequencies.
The Fairfield Pumped Storage Facility is located within 1 to 2 km of the earthquake epicenters, and is closer to the epicenters than the strong motion ~ instrument, but it was not damaged by either the 1978
.or: 1979 earthquake. The lack of damage to this facility is particularly significant because it was not designed or constructed to the'same high seismic design standards used for nuclear power plants. (McGuire, 1982). The V.C. Summer Nuclear Station, which is approximately 8 km from- the epicenters of these events was not
-damaged'either.
The lack of correlation between the high peak accelerations recorded for.these'. shallow events and damage to any facility within one or two
' kilometers .of the epicenter shows that high accelerations by themselves are not an indication of damage potential. The high frequency spikes do not contain sufficient energy to overcome the
- inertia of large- structures,- and thus do not affect structural response. Damage to structures comes predominantly from long duration uhaking and not from one or two high frequency, high acceleration, :short duration pulses which represent only small impulsive excitations (Trifunac, 1972).
Murphy and O'Brien (1977) developed an empirical relationship between intensity and acceleration on the basis of data from ' earthquakes in A the- western United States and southern Europe. Nuttli -(1979) h observed that ground motion attenuation for shallow earthquakes 'in the eastern United States is. as rapid as attenuation for western United States-earthquakes. .Therefore, the Murphy and O'Brien (1977) empirical intensity-acceleration relationship might be applicable to shallow eastern United States events. Their relationship predicts a
-peak acceleration of 0.08g .for the epicentral intensity VI-VII shallow earthquake being evaluated.
Nuttli and Herrmann (1984) used a semi-theoretical approach to compute ground accelerations for a shallow earthquake which occurred in Illinois in 1965. This earthquake had an body-wave magnitude of of 3.8, a focal depth of 1.5 km, an epicentral intensity of VII (MM) and .an intensity. of III (MM) at an epicentral distance of 15 km.
They used the relationship:
log 4 = 0.57 + 0.50 mb ~
- 9( *
-0.00069R (EQ A2-1) where ah is the peak horizontal acceleration in cm/seca mb is the body wave magnitude R is the epicentral distance in km h is the focal depth in km r,
C# A2-3
~
7 .-
The . computed \ values of ~ acceleration as a function of epicentral
' distance for~this event are shown in Figure A2-2, and_can be compared gN to; .the peak:: acceleration values determined from the observed
': intensities according to the Murphy 'and O'Brien -(1977) relationship.
'- 4 Nuttlic .and-- Herrmann _ (1984) .used the relationship given by Equation A2-1-even though they indicate it-is only valid for m b it 24.5. 'Nuttli (1984) suggested that the following relationship be used for' earthquakes with mb < 4.5.
~
, log ah = 0.57 +- 0.25 mb - 0.83 log (Ra + h2)1/2
-0.00069R (EQ A2-2)-
where the variables are as defined for Equation A2-1.
Computed acceleration values from Equation A2-2 are also shown in
-Figure A2-2. The three relationships shown in Figure A2-2 indicate a
. wide -. variation in computed peak accelerations for the-same shallow earthquake, demonstrating the difficulty in predicting peak ground motion .for- shallow earthquakes. In fact, the data base used to develop Equations A2-1 and A2-2 was limited to the normal focal depth -earthquakes and their application to shallow earthquakes may not be valid.
As discussed previously, the largest magnitude shallow earthquake to have occurred in the Appalachian Plateau tectonic province had a body-wave magnitude of 3.8. If a similar event should occur at.the BVPS-2 site, .with a median focal depth 'of 1.5 km (midway between 0
- and _3 km), the predicted peak accelerations from Equations A2-1 and A2-2 are 0.214g and 0.024g, respectively.
Appsel et-.al (1983) attempted to estimate theoretically the ground motion from earthquakes with focal depths between 0 and 16 km using a
- sophisticated three-dimensional modeling procedure. However, their study is not directly applicable.for estimating strong ground motion
- for shallow earthquakes at the BVPS-2 site, since the -smallest event
!, they considered had a magnitude of 4.5. This is significantly higher P than the magnitude 3.8 shallow focus event being evaluated for BVPS-
[ 2. Also, Appsel et al (1983) computed response spectra for shallow l' earthquakes for epicentral distances of up to 35 km for stiff soil i'
sites. Comprehensive investigation by Nuttli and Brill (1981) show o 'that shallow earthquakes in the eastern United States are not felt I: beyond 20-25 km from the epicenter.
l' -Shallow earthquakes can occur in the vicinity of the BVPS-2 site,
)
although the likelihood of such an occurrence is extremely low.
A However, if a shallow' earthquake with a magnitude of 3.8 or an intensity of VI-VII (MM) occurred at the BVPS-2 site, predicted peak accelerations range from 0.024g to 0.214g, depending on which
- earthquake-acceleration relationship is used. Experience with eastern United States shallow earthquakes has shown, however, that i these high peak accelerations are associated with high frequency, F short duration ground motions which do not damage large seismically U designed structures. The BVPS-2 design acceleration of 0.125g is A2-4
-based on a- normal focal depth earthquake, and consequently plant
- design is conservative for the effects of shallow earthquakes.
O O
l l
} APPENDIX 2
-REFERENCES Appsel, R.J. ; Hadley, . D.M. ; and Hart, R.S. Effects of Earthquake Rupture
. Shallowness. and Local Soil Conditions on Simulated Ground Motions. Report ;
prepared for U.S. Nuclear Regulatory Commission, NUREG/CR-3102, 1983. ;
Brady, A.G. ; Mork, P.N.; and Fletcher, J.P. Processed Accelerograms from Monticello Dam, Jenkinsville, South Carolina, August 27, 1975 and Later Shocks. USGS Open File Report 81-448. March 1981.
Fletcher, J.B. . A Comparison Between the Tectonic Stress Measured In Situ ;
.and Stress Parameters from Induced Seismicity at Monticello Reservoir, South l Ca rolina '. Journal . of Geophysical Research, Vol. 87, No. B8, pp. 6931-6944, ;
1982.
j Herrmann, R.B., and Nuttli, 0.W. Ground-Motion Modelling at Regional I Distances for Earthquakes in a Continental Interior, II. Effect of Focal L Depth, Azimuth, and Attenuation. International Journal of Earthquake Engineering and Structural Dynamics, Vol. 4, pp. 59-72, 1975. ;
.McGuire, R. Testimony about V.C. Summer Nuclear Station. Atomic Safety and Licensing Board Hearings, Columbia, SC. Docket 50-395T, 1982.
j Murphy, J.R., and O'Brien, L.J. The Correlation of Peak Ground Acceleration !
N A
Amplitude with Seismic Intensity and Other Physical Parameters. Bulletin of the Seismological Society of America, Vol. 67, No. 3, pp. 877-915, 1977.
-Nuttli, 0.W. Instrumental Data. Contained in Nuttli, 0.W.; Rodriguez, R.;
and Herrmann, R.B. Strong . Ground Motion Studies for South Carolina Earth- 1 r
quakes. Nuclear Regulatory Commission, NUREG/CR-3755. April 1984. ;
Nuttli, O.W., and' Brill, K.G., Jr. Earthquake Source Zones in the Central United States Determined from Historical Seismicity in An Approach to Seismic Zonation for Siting Nuclear Electric Power Generating Facilities in -
the Eastern United States. U.S. Nuclear Regulatory Commission Report NUREG/CR-1577, pp.98-143, 1981. .
Nuttli, O.W., and Herrmann, R.B. Strong Ground Motion Relations for l Mississippi Valley Earthquakes. Paper presented at ASCE Meeting held in St. J Louis, Missouri, October, 1981.
Nuttli, O.W., and Herrmann, R.B. Ground Motion of Mississippi Valley .
Earthquakes. Journal of Technical Topics in Civil Engineering, Vol. 110, No. 1, pp. 54-69, 1984.
Trifunac, M.D. Stress Estimates for the San Fernando, California Earthquake of February 9, 1971: Main Event and Thirteen Aftershocks, Bulletin of the Seismological Society of America, Vol. 62, No. 3, pp. 721-750, 1972.
O A2-6
TABLE A2-1 O VERY SHALLOW EARTHQUAKES
~
WITHIN 200 MILES OF BEAVER VALLEY POWER STATION Date Time Latitude Longitude I g Source
'N - 'W (MO) 08/17/1877 16:50 42.3 83.3 IV-V 3.2 CSR 04/09/1900 14:00 41.4 81.8 VI 3.8 APP 06/27/1906 12:10 40.4 81.6 V 3.4 APP 11/05/1926 15:53 39.1 82.1 VI-VII 3.4 CSR 09/30/1930 20:40 40.3 84.3 VII 4.2 Anna , Ohio -
01/22/1932 41.1 81.5 V 3.6 APP 05/26/1955 18:09 41.5 81.7 IV-V 3.6 APP 06/29/1955 01:16 41.5 81.7 IV 3.6 APP 01/01/1966 13:23 42.8 78.2 VI 4.6 Clarendon
.rh Linden 06/13/1967 19:08 42.9 78.2 VI 4.4 Clarendon Linden CSR - Central Stable Region APP - Appalachian Plateau Province O
1 of 1
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se \ < 3 SHALLOW EARTHQUAKE EPICENTERS
'<* n- .a.
N_ .r i
//.o. rc 7" WITHIN 200 MILES OF THE SITE BE AVER VALLEY POWER STATION-UNIT 2 STONE E WEBSTER ENGINEERING CORPORATION BLUE RIDGE
1000 p _
~
T 0.5 m b too aL -
3 - \ !
\ ;
N E i s -
MURPHY E _
E O'BRIEN ,
~
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5 N
a m N i e
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10 -- !
~
_ ii
_ i
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, i i ,iiiiil i i i i iiii l 1 10 100 ,
OlSTANCE (km) ;
LEGEND:
A ACCELERATIONS DETERMINED FROM i
OBSERVED INTENSITIES AND MURPHY
& O'BRIEN (1977) RELATIONSHIP NOTE: ACCELERATION VS DISTANCE g DATA FROM NUTTLI C HERRMANN (19B4) FOR 1965 ILLINOIS EARTHQUAKE
( BEAVER VALLEY POWER STATION-UNIT 2 STONE G WEBSTER ENGINEERING CORPORATION f i
1 i
O APPENDIX 3 SHEAR WAVE VELOCITY CONTRAST SITE MATCHED RECORDING STATIONS O
O
7 4
Tt Z (
SHEAR WAVE VELOCITY CONTRAST SITE MATCHED RECORDING STATIONS
,' . General 7
This appendix provides - a summary of the evaluation of velocity contrast ratios at the recording stations selected as site matched to BVPS-2 and used -in the site matched response spectra analyses presented in Section 3.
The . velocity contrast ratio-is defined as the shear wave velocity of the rock or'of a rock-like base layer divided by the shear wave velocity of :the =immediately' overlying soil layer. Table A3-1 is a
-summary of the velocity contrast ratios determined for each of the site matched recording stations.-- Available soil profile and shear wave velocity data at-each of the stations are shown in Figures A3-1 through A3-6.
- Alexander Building, San Francisco, California The' bedroc'k _ underlying the station is the, Franciscan Assemblage.
From measurements made at Golden Gate Park in San Francisco, .its shear wave velocity .is estimated to be 3000 ft/sec (Appendix 3, SWEC, 1984).- The shear wave velocity of the soil directly overlying the rock is about 1600 ft/sec, which gives a velocity contrast ratio of 1.9.
. . State Building, San Francisco, California The bedrock underlying the station is the Franciscan Assemblage with a shear .w ave velocity of 3000 ft/sec. Shear wave velocity
- measurements extend to a depth of about 100 ft, but the top of the rock is at a. depth of 211 ft. Assuming that the shear wave velocity at the 100 ft. depth of 1600 ft/sec remains relati'ely v constant for the rest of the soil' profile gives a velocity contrast ratio of 1.9.
City Hall, Oakland, California The shear wave velocity profile for the first 91 ft matches BVPS-2 very well; no data are provided below 91 ft. Seed and Idriss (1969) developed a soil profile model at this station showing a very dense,
~ hard clay below 91 ft that extends to a depth of 1000 ft. The shear modulus of' the soil' layer above the clay.was estimated to be 4.75 x
- 108 psf and the shear modulus of the clay was estimated to be 36 x 108' psf. Clearly, there is a significant velocity contrast at a depth of .91 f t. The ratio of the shear wave velocities of the layers
-are approximately equal to the ratio of the square root of the shear moduli, which gives a velocity contrast ratio of 2.8.
A3-1
r _ _.
Old Ridge Route, Castaic, California
/ The shear wave velocity profile at the station indicates a very
('"]) weathered sandstone to a depth of about 70 ft, at which the shear wave velocity abruptly increases, indicating a more competent, rock like, material. The velocity contrast at this depth is about 2.0, 6074 Park Drive, Wrightwood, California The soil at the station is described as a silty, sandy gravel and is classified as Quarternary Alluvium. Shear wave velocity data at the station are not available, but from measurements made at other recording stations in the Los Angeles area, the average shear wave velocity of the Quarternary Alluvium is about 1200 ft/sec (SW-AA, 1980). Assuming that the shear wave velocity of the rock is 3000 ft/sec gives an estimated velocity contrast ratio at this station of 2.5.
Federal Building, Eureka, California The soil profile at the station consists of about 350 ft of Quarternary and Pleistocene sediments. According to SW-AA (1979),
the Hookton formation is estimated to have a maximum thickness of 400 ft in the Eureka area, so it is likely that the boring was
! terminated at the top of rock. The bedrock in the Eureka area is of the Franciscan Assemblage (SW-AA, 1979).
At a depth of between 120 ft and 140 ft there is an increase in shear f) wave velocity from about 1250 ft/see to 2000 ft/sec. Experience has V shown that for a soil profile such as this, only the upper 100-150 ft of soil is a significant contributor to the amplified response at the ground surface. Therefore, it may be appropriate to consider that the soil profile is truncated at the level of the first velocity contrast. At this depth, the velocity contrast ratio is 1.6.
At the 350 ft depth, the shear wave velocity of the soil is 2000 ft/sec. Assuming that the shear wave velocity of the Franciscan Assemblage rock is 3000 ft/sec gives a velocity contrast ratio at the top of rock of 1.5.
O V
- A3-2
APPENDIX 3 REFERENCES Seed, H.B. and Idriss, I.M. Influence of Soil Conditions on Ground Motions During Earthquakes. Journal of the Soil Mechanics and Foundations Division, ASCE. Vol 95, No. SM1, January, 1969.
.Shannon and Wilson and Agbabian Associates (SW-AA). Geotechnical Data from Accelerograph Stations Investigated During the Period 1975-1979, Summary Report. Prepared for the U.S. Nuclear Regulatory Commission. NUREG/CR-1643, 1980.
Stone & Webster Engineering Corporation (SWEC). Seismic Design Response Spectra, Beaver Valley Power Station - Unit 2. Prepared for Duquesne Light Company, Pittsburgh, PA., June, 1984.
J A3-3
TABLE A3-1 VELOCITY CONTRAST RATIOS.
SITE MATCHED RECORDING STATIONS Velocity Contrast Station Name Ratio Alexander Building San Francisco, CA 1.9 State Building San Francisco, CA 1.9 City Hall Oakland, CA 2.8 4
Old Ridge Route Castaic, CA 2.0-6074 Park Drive Wrightwood, CA 2.5 Federal Building Eureka, CA 1.5-1.6 O
1 of 1
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SAN FRANCISCO, CALIFORNIA FIGURE A3-1
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Roset ten e Beet stee of pett street, hetenee fort street and unres H mayan to bedseet to the etete esaden -te avoces, appeestnotely See feet north of guate vertente taehlester, 49,te, 43 of the State S149. to state Det teleg.
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eu.e.
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STATE BUILDING
...s t.e.
,0 .. es eest .e.e 4 . ...te e .t.te uomo.
. - , . . . . . SAN FRANCISCO, CALIFORNIA
\ e., . n . . ..
FIGURE A3-2
/
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sl = .uan iv,i
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&e .atheh bemen.t eest.
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CITY HALL OAKLAND, CALIFORNIA
\
FIGURE A3-3
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{q sattrsty sagtPee van.r=m e = iv.1 eos,. "C 8" " '" e . .. a ine mee ese un e- e
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SUMMARY
LOG OLD RIDGE ROUTE -
CASTAIC, CALIFORNIA FIGURE A3-4
O WBE LAE 8 Dette te very desse (9), esity, cessf. flee le etette (seeVEL.
elle esteeseest eteeles et seeltest telee SS f t.
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I ta=
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toolse elevottaes Approelmetely 99.9 feet.IISL (USGS ter89fe9hte goed.)
1 meetness il feet f rom eeeeleregrept stettes Date Seetese Se-AA (197161 Dges pseeste mobile D-G.l .elles etes Geget megeree 0 39 feet eespite9 only eetstag roteres.
settened to rotary metaw at feet ned eemptoe seet roteses eed ettenyted 3.e3 sorte noteeee et ete . tag 9 feet.
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SUMMARY
LOG 6074 PARK DRIVE WRIGHTWOOD, CALIFORNIA
\
FICURE A3-5
thf4 SEIMRf U I
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.
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FIGURE A3-6
O APPENDIX 4 EARTHQUAKE, RECORDING STATION, AND CORRECTED ACCELEROGRAM DATA O
O
EARTHQUAKE, RECORDING STATION AND CORRECTED ACCELEROGRAM DATA General This appendix provides the information and data, with references, for the earthquakes and recording stations which are summarized in Table 4.3. It also provides data on the corrected accelerograms which were utilized in the soil iesponse analysis discussed in Section 4, and shown on Tables 4.4 and 4.5.
Earthquake and Recording Station Data The data and informatien for the earthquakes and recording stations summarized in Table 4.3 are provided in numerical order, with the numbers corresponding to the reference numbers of Table 4.3.
No. 1 Helena, Montana The October 31, 1935, Helena, Montana earthquake occurred at 11:38 Hountain Standard Time. It had a Richter magnitude of 6.0 and an epicentral location of 46.62* north latitude and 112.0* west longitude (SW-AA, 1980a). This event was recorded at the Federal Building accelerograph station, located at 46'35'23" north latitude and 112'02'25" west longitude, at an epicentral distance of 4 mi (6.4 km) (SW-AA, 1980a). Kanamori and Jennings (1978) have calculated a local magnitude of 5.30 and 5.70 for the north-south and east-west components of this event, respectively, and an epicentral
~'y distance of 5.0 km. The subsurface conditions at this station x
~
) consist of weathered Precambrian limestone (SW-AA, 1980a). It should be noted that this earthquake record is attributed to the carroll College seismograph station by Trifunac et al, (1975); however, the carroll College Station was not established until June 1940, when the accelerograph was removed from the Federal Building and installed on the carroll College campus (SW-AA, 1980a).
No. 2 Helena, Montena The October 31, 1935, Helena, Montana earthquake occurred at 12:18 Hountain Standard Time. It had an epicentral location of 46.628 north latitude and 112.0* west longitude and r.o reported magnitude (SW-AA, 1980a). This event was recorded at the Federal Building accelerograph station, located at 46'35'23" north latitude and 112'02'25" west longitude, at an implied epicentral distance of 4 mi (6.4 km) (SW-AA, 1980a). Kanamori and Jenninge (1978) have calculated a local magnitude of 4.05 and 3.90 for the north-south and east-west components of this event, respectively, and an epicentral distance of 5.0 km. The subsurface conditions for this station consist of weathered Precambrian limestone (SW-AA, 1980s).
p
{) A4-1
No. 3 Helena, Montana
~~ The November 21, 1935, Helena, Montana earthquake occurred at 20:58
) Hountain Standard Time. It had an epicentral location of 46.62*
north latitude and 112.0' west longitude and no reported magnitude (SW-AA, 1980a). This event was recorded at the Federal Building accelerograph station, located at 46'35'23" north latitude and 112'02'25" west longitude, at an implied epicentral distance of 4 mi (6.4 km) (SW-AA, 1980a). Kanamori and Jennings (1978) have calculated a local magnitude of 3.70 and 3.95 for the north-south and east-west components of this event, respectively, and an epicentral distance of 5.0 km. The subsurface conditions for this station consist of weathered Precambrian limestone (SW-AA,1980a).
No. 4 Helena, Montana The November 28, 1935, Helena, Montana earthquake occurred at 07:42 Hountain Standard Time. It had an epicentral location of 46.62' north latitude and 112.0' west longitude and no reported magnitude (SW-AA, 1980a). This event was recorded at the Federal Building accelerograph station, located at 46'35'23" north latitude and 112'02'25" west longitude, at an implied epicentral distance of 4 mi (6.4 km) (SW-AA, 1980a). Kanamori and Jennings (1978) have calculated a local mag 11tude of 5.0 for the north-south and east-west components of this event, and an epicentral distance of 5.0 km. The '
subsurface conditions for this station consist of weathered Precambrian limestone (SW-AA, 1980a).
No. 5 San Francisco, California
/'~'}
The March 22, 1957, San Francisco, California earthquake occurred at 11:44 Pacific Standard Time. It had a Richter magnitude of 5.3 and an epicentral location of 37'40' north latitude and 122'29' west longitude (SW-AA, 198Cc). This event was recorded at the Golden Gate Park accelerograph station, located at 37'46'19" n' orth latitude and 122'28'37" west longitude (SW-AA, 1980b). This station has an epicentral distance of 7 mi (11.3 km) (SW-AA,1980c). The subsurface conditions at this station consist of thin alternating beds of radiolarian chert and shale. Below a few feet of weathered rock, the chert is hard and brittle and the shale is moderately hard and brittle. This bedrock is part of the Franciscan basement complex (SW-AA, 1980b).
No. 6 Parkfield, California The June 28, 1966, Parkfield, California earthquake occurred at 04:26:12.4 Greenwich Hean Time. It had a Richter magnitude of 5.6 and an epicentral location of 35'54' north latitude and 120'54' west longitude (SW-AA, 1980c). This event was recorded at the Temblor accelerograph station of the Cholame-Shandon Array located located at 35'42'36" north latitude and 120'10'12" west longitude (SW-AA, 1980b), at an epicentral distance of 24 mi (38.6 km) (SW-AA,1980c).
The subsurface conditions at this station consist of serpentinite and O
( ,) A4-2
serpentinized peridotite that are moderately weathered at the surface and highly sheared and brecciated throughout. The rock varies from
-~n moderately hard to hard below a thin zone of weathering (SW-AA, j 1980b).
No. 7 Lycle Creek, California The Lytle Creek, California earthquake of September 12, 1970, occurred at 06:30 Pacific Standard Time. It had a Richter magnitude of 5.4 and an epicentral location of 34'16' north latitude and 117'32' west longitude (EW-AA, 1980c). This event was recorded at the Cedar Springs Allen Ranch accelerograph station located at 34'16'38" north latitude and 117'20'04" west longitude (SW-AA, 1980b), at an epicentral distance of 12 mi (19.3 km) (SW-AA,1980c).
The subsurface conditions at this station consist of granitic basement rock that is hard and fresh near the surface (SW-AA, 1980b).
No. 8 San Fernando, California The February 9, 1971, San Fernando, California earthquake occurred at 06:00 Pacific Standard Time. It had a Richter magnitude of 6.4 and an epicentral location of 34*24.7' north latitude and 118*24.0' west longitude (SW-AA, 1978). This event was recorded at the Lake Hughes Array No. 4 accelerograph station located at 34'38'53" north latitude and 118'28'56" west longitude (SW-AA, 1980b), at an epicentral distance of 18 mi (29.0 km) (SW-AA, 1980c). The subsurface conditions at this station consist of moderately weathered granitic bedrock that is moderately to strongly decomposed to depths f') of about 15 ft, with fresher rock below (SW-AA, 1980b).
\ !
No. 9 San Fernando, California The February 9, 1971, San Fernando, California earthquake occurred at 06:00 Pacific Standard Time. It had a Richter magnitude of 6.4 and an epicentral location of 34'24.7' north latitude and 118*24.0' west longitude (SW-AA, 1978). This event was recorded at the Lake Hughes Array No. 9 accelerograph station located at 34'36'28" north latitude and 118'33'40" west longitude (SW-AA, 1980b), at an epicer. tral distance of 17.9 mi (28.8 km). The subsurface conditions at this station consist of 9 ft of silty and gravelly sand overlying granitic gneiss (SW-AA, 1978).
No. 10 San Fernando, California The February 9, 1971, San Fernando, California earthquake occurred at 06:00 Pacific Standard Time. It had a Richter magnitude of 6.4 and an epicentral location of 34'24.7' north latitude and 118*24.0' west longitude (SW-AA, 1978). This event was recorded at the Lake Hughes Array No. 12 accelerograph station located at 34'34'17" north latitude and 118'33'35" west longitude (SW-AA, 1980b), at an epicentral distance of 15 mi (24.1 km) (SW-AA, 1980c). The subsurface conditions at this station consist of 5 to 10 ft of n
i i C' A4-3
r landslide debris overlying moderatey hard sandstone conglomerate and shale (SW-AA, 1980b).
' No. 11 Cape Mendocino, California The January 12, 1975, Cape Mendocino, California earthquake occurred at 01:37:17.2 Universal Time. It had a Berkeley magnitude of 4.4 and an epicentral location of 40.22* north latitude and 124.26* west longitude (Coffman and Stover, 1977). This event was recorded at the Petrolia Cape Mendocino accelerograph station (USGS #1249, CDMG #5) located at 40.35' north latitude and 124.35' west longitude (Coffman and Stover, 1977). The epicentral distance was calculated to be 16.5 km. The subsurface conditions at this station consist of Cretaceous Franciscan volcanic sandstone (graywacke), with intercalated shales, disturbed by Quarternary landslides (Sherburne, 1984).
No. 12 Cape Mendocino, California The June 7, 1975 Cape Mendocino, California earthquake occurred at 08:46:22.4 Universal Time. It had a Berkeley magnitude of 5.2 and an epicentral location of 40.57' north latitude and 124.14' west longitude (Coffman and Stover,1977). This event was recorded at the Petrolia Cape Mendocino accelerograph station (USGS #1249, CDMG #5) located at 40.35' north latitude and 124.35' west longitude (Coffman and Stover, 1977). The epicentral distance was calculated to be 30.2 km. The subsurface conditions at this station consist of
_ Cretaceous Franciscan volcanic sandstone (graywacke), with
[sh J intercalated shales, disturbed by Quarternary landslides (Sherburne,
_- 1984).
No. 13 Oroville, California The August 1, 1975, Oroville, California earthquake occurred at 12:20 Pacific Standard Time. It had a Berkeley local magn'itude of 5.7 and an epicentral location of 39.44* north latitude and 121.53* west longitude (Maley et al, 1975). This event was recorded at the Oroville Dam crest, at an epicentral distance of 11 km. The subsurface conditions at this station are described as an earthfill dam (Maley et al, 1975).
- No. 14 Oroville, California l
The August 1,1975, Oroville, California earthquake occurred at 12:20 Pacific Standard Time. It had a Berkeley local magnitude of 5.7 and an epicentral location of 39.44' north latitude and 121.53' west longitude (Maley et al, 1975). This event was recorded at the Oroville Dam Seismograph Station, at an epicentral distance of 12 km.
The subsurface conditions at this station are described as meta-volcanic rock (Maley et al, 1975).
e n i
\' / A4-4
I No . 15 Oroville, California Aftershock
~
The August 6, 1975, Oroville, California aftershock occurred at
^ , 03:50:29.7 Universal Time. It had a Berkeley local magnitude of 4.7 at a focal depth of 10.4 km. The location of the epicenter was at 39'29.95' north latitude and 121 31.53' west longitude (Toppozada et al, 1975). This event was recorded at the Don Johnson Ranch (DJR) with an hypocentral distance of 13.3 km. The epicentral distance was calculated to be 8.3 km. The DJR accelerograph is located at 39*25.47' north latitude and 121'31.26' west longitude. The site geology is described as greenstone-sediment contact, with the greenstone 10 meters below the surface (Toppozada et al, 1975).
Weston (1981) reports that there are 10 meters of Pleistocene gravels and alluvium overlying bedrock at the Don Johnson Ranch and that the measured shear wave velocity of the overburden is 1,100 ft/sec and is 5,000 ft/sec for the bedrock.
No. 16 Oroville, California Aftershock The August 8, 1975, Oroville, California aftershock occurred at 07:00:50.6 Universal Time. It had a Berkeley local magnitude of 4.9 at a focal depth of 6.8 km. The location of the epicenter was at 39 29.92' north latitude and 121 30.10' west longitude (Toppozada et al, 1975). This event was recorded at the Don Johnson Ranch (DJR) with an hypocentral distance of 10.8 km. The epicentral distance was calculated to be 8.4 km. The DJR accelerograph is located at 39 25.47' north latitude and 121'31.26' west longitude. The site
,__. geology is described as greenstone-sediment contact, with the
/
') greenstone 10 meters below the surface (Toppozada et al, 1975).
w- Weston (1981) reports that there are 10 meters of Pleistocene gravels and alluvium overlying bedrock at the Don Johnson Ranch and that the measured shear wave velocity of the overburden is 1,100 ft/sec and is 5,000 ft/sec for the bedrock.
No. 17 Oroville, California Aftershock The August 8, 1975, Oroville, California aftershock occurred at 07:00:50.6 Universal Time. It had a Berkeley local magnitude of 4.9 at a focal depth of 6.8 km. The location of the epicenter was at 39'29.92' north latitude and 121*30.10' west longitude (Toppozada et al, 1975). This event was recorded at the California Division of Mines and Geology Station No. 6, referred to as Oroville No . 6, located at 39'26.938 north latitude and 121*29.38' west longitude.
The epicentral distance was calculated to be 5.6 km. The Oroville No. 6 site geology is described as Mesozoic greenstone (Toppozada et al, 1975).
No. 18 Oroville, California Aftershock The September 27, 1975, Oroville, California af tershock occurred at 22:34 Universal Time. It had a Berkeley local magnitude of 4.6 at a focal depth of 12.0 km. The location of the epicenter was at 39*31.34' north latitude and 121'31.74' west longitude (seekins and O
j A4-5
Hanks,1978). This event was recorded at the Don Johnson Ranch (DJR) accelerograph station located at 39'25.47' north latitude and 121'31.26' west longitude. The epicentral distance was calculated to
(
) be 10.9 km. The DJR site geology is described as greenstone-sediment V contact, with the greenstone 10 meters below the surface (Toppozada et al, 1975). Weston (1981) reports that there are 10 meters of Pleistocene gravels and alluvium overlying bedrock at the Don Johnson Ranch and that the measured shear wave velocity of the overburden is 1,100 ft/sec and is 5,000 ft/sec for the bedrock.
No. 19 Oroville, California Aftershock The September 27, 1975, Oroville, California aftershock occurred at 22:34 Universal Time. It had a Berkeley local magnitude of 4.6 at a focal depth of 12.0 km. The location of the epicenter was at 39'31.34' north latitude and 121*31.74' vest longitude (Seekins and Hanks, 1978). This event was recorded at the California Division of Mines and Geology Station No. 8, referred to as Oroville No. 8, located at 39'26.35' north latitude and 121'28.03' west longitude.
The epicentral distance was calculated to be 11.0 km. The Oroville No. 8 site geology is described as Mesozoic greenstone (Toppozada et al, 1975).
No. 20 Friuli, Italy Aftershock The September 11, 1976, Friuli, Italy aftershock occurred at 16:35:00 Greenwich Mean Time. It had a loc >.1 magnitude of 5.9, a focal depth of 6 km, and ' an epicentral location of 46*19' north latitude and (3 13'10' east longitude (Basili et al, 1978). This event was recorded Q Ct the Somplago (D) accelerograph station, at an epicentral distance ot' 6.0 km. The Somplago (D) accelerograph is located at 46*20'33" nor*.h latitude and 13'03'58" east longitude, inside the underground powerhouse of a hydroelectric station approximately 260 meters below the aurface (Basili et al, 1978). Basili et al (1978) report the materials upon which the instrument rests to be a f'ractured complex of Triassic limestone and dolomite. Muzzi and Vallini (1978) report that the compression wave velocity of the rock below the accelerograph was measured to be about 4.3 km/sec (14,100 ft/sec) by a geophysical seismic survey.
No. 21 Friuli, Italy Aftershock The September 11, 1976, Friuli, Italy aftershock occurred at 16:35:00 Greenwich Mean Time. It had a local magnitude of 5.9, a focal depth of 6 km, and an epicentral location of 46'19' north latitude and 13'10' east longitude (Basili et al, 1978). This event was. recorded at the San Rocco accelerograph station, at an epicentral distance of 14.5 km. The San Rocco accelerograph is located at 46 13'35" north latitude and 12'59'59" east longitude (Basili et al, 1978). Muzzi and Vallini (1978) state that the San Rocco Station site is at an outcropping of hard limestone. A more detailed description of this material reports it to be stratified and fissured Cretaceous g
( ,e A4-6
limes tone , a few tens of meters thick, overthrust on Miocene sandstone and marl (CNEN-ENEL, 1976).
? .
L,) No. 22 Friuli, Italy Aftershock The September 11, 1976, Friuli, Italy aftershock occurred at 16:31:12 Greenwich Mean Time. It had a local magnitude of 5.5, a focal depth of 9 km, and an epicentral location of 46'17' north latitude and 13'10' east longitude (Basili et al, 1978). This event was recorded at the San Rocco accelerograph station, at an epicentral distance of 15.5 km. The San Rocco accelerograph is located at 46'13'25" north latitude and 12*59'59" east longitude (Basili et al, 1978). Muzzi and Vallini (1978) state that the San Rocco Station site is at an outcropping of hard limestone. A more detailed description of this material reports it to be stratified and fissured Cretaceous limestone, a few tens of meters thick, overthrust on Miocene sandstone and marl (CNEN-ENEL, 1976).
No. 23 Friuli, Italy Aftershock The September 11, 1976, Friuli, Italy aftershock occurred at 16:31:12 Greenwich Mean Time. It had a local magnitude of 5.5, a focal depth of 9 km, and an epicentral location of 46*17' north latitude and 13'10' east longitude (Basili et al, 1978). This event was recorded j at the Somplago (D) accelerograph station, at an epicentral distance of 10.0 km. The Somplago (D) accelerograph is located at 46'20'33" north latitude and 13'03'58" east longitude, inside the underground powerhouse of a hydroelectric station approximately 260 meters below l j the surface (Basili et al, 1978). Basili et al (1978) report the N-/ materials upon which the instrument rests to be a fractured complex of Triassic limestone and dolomite. Muzzi and Vallini (1978) report that the compression wave velocity of the rock below the accelerograph was measured to be about 4.3 km/sec (14,100 ft/sec) by a geophysical seismic survey.
No. 24 Friuli, Italy Aftershock The September 15, 1976, Friuli, Italy aftershock occurred at 04:38:53 Greenwich Mean Time. It had a local magnitude of 5.0, a focal depth of 21.5 km, and an epicentral location of 46*16' north latitude and 13'10' east longitude (Basili et al, 1978). This event was recorded at the Somplago (D) accelerograph station, at an epicentral distance of 11.3 km. The Somplago (D) accelerograph is located at 46*20'33" north latitude and 13*03'58" east longitude, inside the underground powerhouse of a hydroelectric station approximately 260 meters below the surface (Basili et al, 1978). Basili et al (1978) report the materials upon which the instrument rests to be a fractured complex of Triassic limestone and dolomite. Muzzi and Vallini (1978) report that the compression wave velocity of the rock below the accelerograph was measured to be about 4.3 km/sec (14,100 ft/sec) by a geophysical seismic survey.
p x~/ A4_7
+No. 25 -Friuli, Italy Aftershock The September 15, 1976, Friuli, Italy aftershock occurred at 09:21:28
-Greenwich Mean Time. It.had a local magnitude of 6.0, a focal depth
. o f 12 km , - and- an epicentral location of 46*20' north latitude and 13'10 east longitude (Basili et al, 1978). This event was recorded at. the-San Rocco accelerograph station, at an. epicentral distance of 19.0 km. . Thel San Rocco accelerograph is located at 46'13'35" north latitude and 12'59'59" east longitude, (Basili'et al,-1978). Muzzi and Vallini(1978) state that the San Rocco' Station site is at an outcropping of hard limestone. A more detailed description of this Laaterial- reports . it to be stratified and fissured Cretaceous climestone, a few . tens of meteis thick, overthrust on Miocene sandstone and marl (CNEN-ENEL, 1976).
'No. 26 Santa Barbara, California The August 13,~1978,. Santa Barbara, California Earthquake occurred at 22:54:52.4. It had a local magnitude of-5.1, a focal' depth of 12.5 km, - and -an epicentral location of 34*22.2' north latitude and 119'43.0' west longitude (Porter, 1978). This event was recorded at the North Hall accelerograph station located on the University of California Santa Barbara campus in Goleta, California. This station
.is located at 34.415' north latitude and 119.846' west longitude and
~
had an epicentral distance of 12.75 km (Porter, 1978). The accelerograph is attached to the topside of a 4 inch thick reinforced concrete floor slab supported by tie beams between caissons. (Porter, 1978). . Weston (1981). reports that the North Hall foundation consists
- / V of a concrete slab at grade resting on bell-shaped caissons which extend through 13 ft of alluvial material and are bottomed in siltstone of the Sisquoc Formation. The shear wave velocity of the siltstone is 2,000 to 2,500 ft/sec, based on field observation.
No. 27 Coyo.te Lake, California .
The August 6, 1979, Coyote Lake, California earthquake occurred at 17:05:22.71 Universal Time. It has a local magnitude of 5.9, a focal
- depth of 6.3 km, and an epicentral location of 37'6.12' north latitude and 121'30.20' west longitude (Uhrhammer, 1980). This event was recorded . at the. San Martin, California, Coyote Creek accelerograph. station at an epicentral distance of 2 km. . The accelerograph! is located at 37.118* north latitude and 121.550' west longitude.- The site. geology is described as conglomerate (Procella'
-et -al, 1979). Brady et al (1981) describe the station location as a rock site consisting of Cretaceous age Berryessa Formation, which consists of Oakland conglomerate, sandstone, and shale.
No. 28 Coyote Lake, California
=The.' August 6, _1979' Coyote . Lake, California earthquake occurred at 17:05:22.71- Universal Time. It had a local magnitude of 5.9, a focal
~ depth of.'6.3 km,. and an epicentral location of 37'6.12' north
~
latitude and 121*30.20' west longitude (Uhrhammer, 1980). This event A4-8 w-%Je-e eme a -h wes-e + m+
was recorded 'at the Gilroy 'No. I accelerograph station at an epicentral distance of 16 km. This station is located at the Gavilan f3 College water tower at 36.973* north ' latitude-and 121.572* west
( j- longitude. 'The site geology is described as Franciscan sandstone
' (Porcella et al, 1979). Brady et al (1981) describe the station location as aorock site, consisting of Cretaceous-Jurassic age Franciscan Formation, which consists of sandstone, shale, and chert.
The compression wave and shear wave velocities of the Franciscan rock were measured in a 20-meter deep boring at the station site, and were found to be 3.1 km/sec (10,200 ft/sec) and 2.0 km/sec (6,600 ft/sec),
respectively (Joyner et al, 1981).
No. 29 Coyote Lake, California-The August 6, 1979, Coyote Lake , California earthquake occurred at 17:05:22.71 Universal Time. It had a local magnitude of 5.9, a focal depth of 6.3 km, and an epicentral location of 37*6.12' north latitude and 121*30.20' west longitude (Uhrhammer, 1980). This event was recorded at the Gilroy No. 6, San Ysidro accelerograph station at
.an epicentral distance of 10 km. This station is located at 37.026*
north latitude and 121.484* west longitude. The site geology is described as Berryessa congolomerate (Porcella et al, 1979). Brady et al (1981) describe the station location as a rock site, consisting of Cretaceous age Berryessa Formation, which consists of Oakland conglomerate, sandstone, and shale.
No. 30 Livermore, California
(T i
The January 26, 1980, Livermore, California earthquake occurred at 06:33:35.96 Pacific Standard Time.
s ,/ The University . of California, Berkeley Seismograph Station reported a local magnitude of 5.8, an epicentral location of 37.74* . north latitude and 121.74* west longitude, and a focal depth of 14.5 km. t The United States Geological Survey at Menlo Park reported a local magnitude of 5.2, an epicentral location of 37.76* north latitude and 121.70* west
. longitude, and a focal depth of 7.3 km (McJunkin and Ragsdale,1980).
This -event 'was recorded at the Livermore-Morgan Territory Park accelerograph station, located at 37.819* north latitude and 121.795*
west longitude, at an epicentral distance of 11.0 km. This station is underlain by Upper Cretaceous undifferentiated Great Valley sandstone and shale (McJunkin and Ragsdale, 1980).
No. 31 New Hampshire The January 18, 1982, New Hampshire earthquake occurred at 19:14:42 Eastern Standard Time. It had a Richter magnitude of 4.7, a body-wave' magnitude of 4.4, a focal depth between 4.5 and 8.0 km, and an epicentral location of 43.5* north latitude and 71.6* west longitude (Chang, 1983). This event was recorded at the Franklin Falls Dam right abutment accelerograph station, located at 43.447* north latitude and 71.660* west longitude, at an epicentral distance of 8 km.
\ -
A4-9
F This accelerograph station is reported to be a rock site by chang (1983). SWEC reviewed available data from U.S. Army Corps of
~', Engineers borings made prior to construction of the dam and visited
! the dam site to confirm the foundation conditions for the right abutment accelerograph station. It is located on the west side of the river valley in an area excavated to form the spillway for the dam. The accelerograph station shelter is founded on what appears to be a rock outcrop, on the top of the lowest of three terraces on the east side of the spillway. It is close to the top of the slope which <
is fairly steep at about IV:2H.
No. 32 New Brunswick Aftershock The March 31, 1982, New Brunswick aftershock occurred at 21:02:20 Universal Time. It has a Nuttli magnitude of 4.8, an epicentral location of 47.00 north latitude, and 66.57' we.st longitude with a focal depth of 4 km (Weichert et al, 1982). The body-wave magnitude was reported to be 5.0 by Wetmiller et al (1984). This event was recorded at the Mitchell Lake Road accelerograph station, located at 47*02.15' north latitude and 66 36.62' west longitude at an epicentral distance of 4.2 km. The foundation for this station is reported as bedrock (Weichert et al, 1982).
Corrected Accelergram Data The corrected earthquake time histories used in the previous submittal (SWEC, 1984) were obtained from the Califronia Institute of Technology (CIT), Earthquake Engineering Laboratory Data Tape
( ). (Volume II), Corrected Accelerograms. CIT stopped the data
\s_,/ processing project in May, 1973, after completing work on the 1971 San Fernando earthquake. Thus, accelerograms corrected by CIT are not available for earthquakes occurring after 1971. Earthquake record correction was taken over by the Seismic Engineering Branch of the U.S. Geological Survey at Menlo Park, California, with distribution of corrected records handled by the National Geophysical Data Center (NGDC) of the National Oceanic and Atmospheric Administration (NOAA). Strong-motion records for some California earthquakes are also corrected and distributed by the California Division of Mines and Geology (CDMG). Unfortunately, corrected records are not available from NGDC vc CDMG for all the earthquakes and recording stations listed in Table 4-4. Stone & Webster obtained uncorrected strong-motion records for those events where corrected reccrds are not available (the Oroville aftershocks and the Friuli aftershocks) and processed them utilizing the computer program SIVA to obtain corrected records. Details of the SIVA processing procedures are contained in Sunder and Connor (1982). Table A4-1 lists all the earthquake records of Table 4-4, with the source of the earthquake record (corrected and/or uncorrected),. information on filter limits used in correcting the strong-motion record, and a comparison of the uncorrected and corrected maximum acceleration values.
I )
\s / A4-10
' APPENDIX 4 l
REFERENCES
. Basili,'M.,. S. Polinari, G.' Tinelli, .R. Berardi, A. Berenzi,. and
'L.' Zonetti.. Strong-Motion Records of.Friuli Earthqu'ake, in Comitato Nazionale Energia' Nucleare (CNEN)'- Proceedings of Specialist Meeting on The 1976 Friuli Earthquake and the Antiseismic Design of Nuclear l Installations, Rome, Italy, 11-13 October,.1977, Vol. II, pp- 375-386.
- May, 1978.1 Brady, A.G., 'P.N. Hork,'V. Perez,fand L.D.' Porter. Processed Data from the -Gilroy' Array -and Coyote Creek Records,- Coyote Lake Earthquake, 6 August 1979, U.S. Geological Survey, Open-File Report 81-42, pp 171. 1981.
Chang,LJF.K. Analysis of Strong-Motion Data from the New Hampshire Earthquake of lu January 1982, NUREG/CR-3327, Report to U.S. Nuclear Regulatory Commission. September, 1983.
l > Comitato Nazionale Energia. Nucleare. - Ente Nazionale Energia
.Elettrica (CNEN-ENEL)' Commission on Seismic Problems Associated with the -Installation; of Nuclear Plants. Contribution to the Study of L Friuli EarthquakeE of May '1976,. Appendix B, CNEN's Geophysical
- Instrumentation,' pp 127-135. November, 1976.
~
l .Coffman, J.L.. and C.W. Stover, Editors. United' States Earthquakes,
'1975, U.S._ Department of Commerce, National.0ceanic and Atmospheric
[ , Administration. and. U.S. -Department of- the Interior, Geological
-Survey, Boulder, Colorado. 1977.
- Joyner, W.B.,.R.E. Warrick, and T.E. Fumal. The Effect of Quaternary.
. Alluvium ~on Strong Ground Motion ~ in .the Coyote' Lake, California,
^t .
pf . Earthquake of 1979, Bulletin of the. Seismiological Society of L " America,1Vol. 71, No. 4, pp 1333-1349. August, 1981'.
Kanamori, .H., and P.C. Jennings. Determination of Local Magnitude,-
from . Strong-Motion 'Accelerograms, Bulletin of the Seismological Society - of America, Vol. 68, No. 2, pp 471-485. April, 1978.
Maley, R.P.,- V. Perez, and B.J. Morrill. Strong-Motion Seismograph Results from the Oroville Earthquake of 1 August 1975, in Oroville, California, ' Earthquake. 1 August 1975, California Division'of Mines-and Geology Special Report 124, pp 115-122. 1975.
<McJunkin, -
R.D., and J.T. Ragsdale. Strong-Motion Records from the Livermore Earthquake of 24 and 26' January 1980, California Division
.of Mines and Geology Preliminary Report 28, pp 91. 1980.
Muzzi, F. and S. Vallini. The Friuli 1976 Earthquake considered as a "Near Source' Earthquake," Presentation and Discussion of the Surface 3 Recordings,. inComitato. Nazionale Energia Nucleare (CNEN) -
. Proceedings of Specialist- Meeting on The 1976 Friuli Earthquake and A4-11
the Antiseismic Design of Nuclear Installations, Rome, Italy, 11-13 October, 1977, Vol. II, pp 460-526. May, 1978.
Porcella, R.L., R.B. Matthiesen, R.D. McJunkin, and J.T. Ragsdale.
Compilation of Strong-Motion Records from the August 6, 1979, Coyote Lake Earthquake, U.S. Geological Survey, Open-File Report 79-385, 1979.
Porter, L.D. , Compilation of Strong-Motion Records Recovered from the Santa Barbara Earthquake of 13 August 1978, California Division of Mines and Geology Preliminary Report 22. October, 1978.
Seekins, L.C. and T.C. Hanks. Strong-Motion Accelerograms of the Oroville Aftershocks and Peak Acceleration Data, Bulletin of the Seismological Society of America, Vol. 68, No. 3, pp 677-689.
June, 1978.
Shannon and Wilson, Inc. and Agbabian' Associates (SW-AA).
Verification of Subsurface Conditions at Selected " Rock" Accelerograph Stations in California, Vol. 1, NUREG/CR-0055, Report Prepared for U.S. Nuclear Regulatory Commission. 1978.
Shannon and Wilson, Inc. and Agbabian Associates (SW-AA),
Geotechnical and Strong-Motion Earthquake Data from U.S.
Accelerograph Stations, NUREG/CR-0985, Vol. 3, Report to U.S. Nuclear Regulatory Commission. 1980a.
Shannon and Wilson, Inc. and Agbabian Associates (SW-AA).
( ,)
Verification of Subsurface Conditions at Selected " Rock"
's / Accelerograph Stations in California, Vol. 2, NUREG/CR-0055, Report to U.S. Nuclear Regulatory Commission. 1980b.
Shannon and Wilson, Inc. and Agbabian Associates (SW-AA). -
Verification of Subsurface Conditions at Selected " Rock" Accelerograph Stations in California, Vol. 2, App'endix, Earthquake Records, NUREG/CR-0055, Report to U.S. Nuclear Regulatory Commission.
1980c.
Sherburne, R.. Personal Communication from California Division of Mines and Geology to R. Borjeson of Stone & Webster Engineering Corporation, October 29, 1984.
Stone & Webster Engineering Corporation (SWEC), Seismic Design Response Spectra, Beaver Valley Power Station - Unit 2. Prepared for Duquesne Light company, Pittsburgh, Pennsylvania. June, 1984.
Sunder, S.S. and J.J. Connor. A New Procedure for Processing Strong-Motion Earthquake Signals. Bulletin of the Seismological Society of America, Vol. No.2, pp 643-661. April, 1982.
Toppozada, T.R., W.H. Wells, J.H. Power, and T.C. Hanks. Strong-Motion Accelerograms of the Aftershocks, in Oroville, California, m
( )
x_/ A4-12
Earthquake, 1 August 1975, California Division of Mines and Geology Special Report 124, pp 101-107, 1975.
t
(.
(
) Trifunac, M.D., A.G. Brady, and D.E. Hudson. Strong-Motion U Earthquake Accelerograms - Digtized and Plotted Data. Vol. II -
Corrected Accelerograms and Integrated Ground Velocity and Displacement Curves: Part B - Accelerograms IIB 021 to IIB 040. Report EERL-7 California Insititute of Technology, Earthquake Engineering-Research Laboratory. February, 1973.
Uhrhammer, R.A., Observations of the Coyote Lake, California Earthquake Sequence of August 6, 1979. Bulletin of the Seismological
. Society of America, Vol. 70, No. 2, pp 559-570. April, 1980.
Weichert, D.H., P.W. Pomeroy, _P.S. Munro, and P.N. Mork. Strong-Motion Records from Miramichi, New Brunswick, 1982 Aftershocks, Earth Physics Branch Open-File Report 82-31, Ottawa, Canada, pp 94. 1982.
Weston Geogphysical Corporation (WGC). Site-Specific Response Spectra, Midland Plant - Units 1 and 2, Addendum to Part 1, Response Spectra - Original Ground Surface, Prepared for Consumers Power Company.~ June, 1981.
Wetmiller, R.J., J. Adams, F.M. Anglin, H.S. Hasegawa, and A.E.
! Stevens. Aftershock Sequences of the 1982 Miramichi, New Brunswick, l Earthquake. Bulletin of the Seismological Society of America, l Vol. 74, No. 2, pp 621-653. April, 1982.
l A4-13 v
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APP (NDIX 4 TABLE A4 -1 CORRECTED ACCELEROGRAM OATA H1oh Pass Filter Low Pass F11ter Peak Acceleration Earthquake Earthquake Term 1- Term 1- (CM/SEC')
Ref Date Recording Record Com- nation Cut Off Cut Off nation No.'" Year Mo Day Station Source '" ponent (Hz) (Hz) (Hz) (Hz) Uncorrected Corrected Ratio *8' 1 1935 to 31 Carrol College. CIT EW O.050 0.070 25.0 27.0 -153.11 142.50 -1.07 Helena MT NS 0.050 .O.070 25.0 27.0 138.38 143.50 0.96 6 1966 06 28 Cholame-Shandon CIT N65W O.050 0.070 25.0 27.0 -276.77 -264.31 1.05 Array. Temblor S25W O.050 0.070 25.0 27.0 -403.38 -340.80 1.18 7 1970 09 12 Allen Ranch. CIT SO5W O.050 0.070 25.0 27.0 -55.94 54.90 -1.02 Cedar Springs. CA S85E O.050 0.070 25.0 27.0 84.40 -69.90 -1.20 8 1971 02 09 Array No. 4 CIT S69E O.100 0.125 25.0 '27.0 196.29 168.20 1.16 Lake Hughes CA S21W O.100 0.125 25.0 27.0 156.05, -143.50 -1.09 14 1975 08 01 Orov111e Dam NOAA N53W O 160 0.590 23.0 25.0 101.38 -82.53 -1.23 Setsmograph N37E O.160 0.590 23.0 25.0 -106.19 90.60 -1.17 Station 17 1975 08 08 Oroville. CA NO A A "' S55E O.886 1.250 35.0 45.4 74.19 75.59 -0.98 CDMG No. 6 N35E 1.139 1.600 35.0 45.2 105.21 97.96 1.07 19 1975 09 27 Oroville. CA NO A A " ' N90W O.886 1.250 35.0 45.4 -150.59 -156.56 0.96 CDMG No. 8 SOO! O.814 1.150 35.0 45.4 -71.90 -72.36 0.99 21 1976 09 11 San Rocco NOAA "' NS 0.245 0.350 25.0 30.5 -89.68 -85.03 1.05 EW O.245 'O.350 25.0 30.5 -89.93 87.47 -1 03 22 1976 09 11 San Rocco NOAA "' NS O.210 0.300 25.0- 30.5 -40.11 -38.58 1.04 EW O.245 0.350 25.0 30.5 68.55 68.20 1.01 25 1976 09 15 San Rocco NOA A "' NS O.175 0.250 25.0 30.6 -138.86 -144.91 0.96 EW O.154 0.220 25.0 30.6 -229.69 -227.89 1.01 27 1979 08 06 Coyote Creek. NOAA 250 0.050 0.250 23.0 25.0 245.26 244.63 1.00 San Martin. CA 160 0.050 0.250 23.0 25.0 138.58 137.72 1.01 28 Gilroy No. 1 NOAA 320 0.050 0.250 23.0 25.0 -115.91 -111.09 1.04 Gavilan College 230 0.050 0.250 23.0 25.0 -93.53 -83.73 1.12 Water Tower 29 Gilroy No. 6 NOAA 320 0.050 0.250 23.0 25.0 -313.48 -314.57 1.00 San Ysidro. CA 230 0.050 0.250 23.0 25.0 -414.08 -408.79 1.01 31 1982 01 18 Franklin Falls WES 45 0.330 50.0 100.0 282.52 287.70 0.98 Dam Right Abutment 315 0.330 50.0 100.0 565.05 -539.96 -1.05
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APPENDIX 4-TABLE A4-1
. CORRECTED ACCELEROGRAM DATA Hton Pass Filter Low Pass Filter Peak Acceleration Earthquake Earthquake . Termt- Ternt- (CN/SEC')
Ref Date Recording- Record Com- . nation Cut Off Cut Off nation No . ' ' Year No Day Station Source "' ponent (Hz) (Hz) (Hz) (Hz) Uncorrected Corrected Ratio _
32 1982 03 31 Mitchell Lake .EPB 118 1.000 50.0 100.0 134.64 -148,77 -0.90 Road 28 1.000 50.0 100.0 -200.66 -231.46- 0.87 NOTES:
"*
- Refer to Table 4-3
"'
- NOAA - United States Department of Commerce. National Oceanic and Atmospheric Administration. National Environmental Satellite. Data, and Information Service. National Geophysical Data Center.
- WES - Department of the Army. Waterways Experiment ~ Station. Corps of Engineers.'Geotechnical Lasoratory.
Earthquake Engineering and Geophysics Division.
- EPB - Energy Mines and Resources Canada. Earth Sciences. Earth Physics Branch. Division of Setsmology and
_ Geomagnetism.
- CIT - California Institute of Technology. Earthquake Engineering Research Laboratory.
"' Ratto of uncorrected to corrected acceleration
"* Uncorrected records were obtained from source noted. R_ecords were corrected by SWEC.
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APPENDIX 5
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SOIL RESPONSE ANALYSIS: UNSCALED t r
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.The -rock outcrop records which. met- the criteria for use without l t
scaling'in the soil response analysis were identified in Table 4-5.
The 10 component recordings of the five earthquakes listed are too l small a data set to be,used for a statistical estimate of population i parameters, namely the 50th .and 84th percentile response spectra. l The size of the data set allows unusual or outlier records to bias the. results of the analysis more than would be possible in a larger i
. data seti-such as that' of the -scaled earthquake records (Table 4-4). .!
Furthermore, four'out of the five earthquakes listed in. Table 4-5 had ,
magnitudes higher than the BVPS-2 SSE, which results in a higher :
response than is appropriate. l In general, response spectra determined from a set of unscaled records for earthquakes having magnitudes within 1 0.5 magnitude units of:a. target magnitude are considered less normative than those determined from scaled records. A range of i 0.5 magnitude units represents .a difference in earthquake energy release between the 1 highest =and lowest magnitude event of about 30 times. This large difference of energy release is reduced by the scaling process.
In . spite of lthe reasons presented demonstrating that an unscaled soil response analysis is inappropriate, the analysis was performed using the records -listed in Table 4-5. The resulting 50th percentile and the 84th percentile response spectra are shown in Figure A5-1.
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O APPENDIX 6 SITE DEPENDENT RESPONSE SPECTRA STATISTICAL ANALYSIS PROCEDURE O
4
- O
. SITE DEPENDENT RESPONSE SPECTRA
- STATISTICAL ANALYSIS PROCEDURE The site matched and soil response analyses provide two separate statistical estimates of the site dependent response spectra. Advantages and limita-tions can be ascribed to each method, and it cannot be stated with certainty
- which one - provides the best ' estimate of the true site dependent spectra.
The two approaches are intended _ to augment each ~other, and therefore, their results are combined in a way that provides the best estimate of the 50th and 84th percentile site - dependent _ response spectra. This appendix de-scribes the statistical procedure and derives the expressions used to combine the site matched and soil response analyses results.
A6.1. Definition of Symbols Symbol Definition 2 Chi-square statistic X
-E(x) Expected value of'the random variable x f Number of degrees of freedom for chi-square distribution MEDV Median site dependent pseudo-velocity, in/sec MSDV 84th percentile site dependent pseudo-velocity, in/sec A
V MSDLOGV Mean plus one standard deviation (84th percentile) logio pseudo-velocity n Number of observations (earthquake records) s2 Variance of the sample logia pseudo-velocities sg Variance of the sample mean logio pseudo-velocities se,sr Subscripts for site matched analysis and soil response analysis, respectiviely 02 Variance of the population of logio pseudo-velocities p Hean of the population of logio pseudo-velocities v Logio pseudo-velocity v Sample mean logio pseudo-velocity Wse,Wsr' Weighting factors for the mean logio pseudo-velocities from ,
the site matched and soil response analyses, respectively (
O '
A6-1
A6.2 ESTIMATION OF THE MEAN
[m
.] The response spectrum - psuedo-velocities are log-normally distributed and therefore, _ standard statistical methods are applied to the base 10 logarithms'of the pseudo-velocities.
An estimate of the population mean logio pseudo-velocity is provided by the linear combination of the mean logio pseudo-velocities from the site matched and soil response analyses as:
v=W *v +W *v (Eq A6-1)
The weighting factors, W and W are derived, -
described below, so that the variance of the estimIte of Me, mean is a minimum.
The expected value of v is:
E(v) = W,,E(V,,) + W (Eq A6-2)
E(isr) and, if both sets of data are drawn from the same population, then:
E(v,,) = E(v,7) =_p (Eq A6-3)
It then follows that:
E(v) = p (W,,+ W ) (Eq A6-4) and if -v is an unbiased estimate of the underlying population mean, p, the sum of the weighting factors is unity; i.e.:
W sa
+Wsr =1 (Eq A6-5)
The variance of the estimate of the mean logio pseudo-velocity is given by the expression:
s1 v
= W2 s1 sm v
+ W2 s1 sr v (Eq A6-6)
Since the variance of the mean for each analysis can be described in terms of the variance of the sample observations as s /n, 2 Equation A6-6 can be rewritten as:
2 2 (Eq A6-7) s1 v = W2sa (ssa/nsm) + W2sr (3sr/nsr) and since W =1-W ,,,
2 2 (Eq A6-8) s1v = W2sm (ssm/nsm) + (1-Wsm)2 (ssr/nsr)
The weighting factors are found by taking the partial derivative of sg with respect to W and setting the result equal to zero for the minimum variance. The s5esulting expressions for W and W are given by:
A6-2
n 2 g y se/s sa a z (Eq A6-9a)
T~ sa na j,se + nsr/s sr sa "srl 'sr (Eq A6-9b) sr n z 2 -+nsr/s sr se/s se Equations A6-9a and A6-9b can be simplified by substituting the following:
R = n,,/s2 _.+ n /s2 7 (Eq A6-10a) which gives:
1 n W,, = p . ,$" (Eq A6-10b) sm I n W (Eq A6-10c) sr *E*s sr The calculations described by equateins A6-1 and A6-10 are carried out at each frequency at which the two sets of spectra are evaluated. All calcula-tions are performed using the logto pseudo-velocities; the conversion to velocity is:
MEDV = 10 (in/sec) (Eq A6-11)
A6.3 ESTIMATION OF THE VARIANCE It can be shown that if s2
~
is the variance of a random saiaple of size a from the nonnal population N(v, p, 0 2), then (n-1)s 2fg2 has a chi-square distribution with (n-1) degrees of freedom. Therefore:
s2 = ya (Eq A6-12)
It can also be demonstrated that if the results of repeated independent samplings from the same population have chi-square values of XI, X3, X3. . .
with f t, _f 2, fs, ... degrees of freedom, respectively, then the individual results are equivalent to a chi-square value given by X} + X3 + X3 +. . .
with ft + f2 + fa+... degrees of freedom. Accordingly, the sum of the chi-square values from the site matched and soil response analyses is:
2 x=x+y 2 2 (nsm-1) s2sm (nn -1) s 2sr X2= , (Eq A6-13a) 0z 0z i O
A6-3
r-with degrees of freedom given by:
/ f = (nsa-1) + (n sr-1) = (n t-2) (Eq A6-13b) y]
where:
"t * "sm + "sr 2
Multiplying both sides of Equation A6-13a by 0 /(ng -2) gives:
02 X2 (nsr-1) s a y (n,,-1) s 2_
- (Eq A6-14a)
(n -2) * (at-2) (nt-2)
And since n sr = 28 and n,,= 18:
s 2=0.6136shr+0.3864s,2 , (Eg A6-14b)
Equation A6-14b provides the best estimate of the variance of the site dependent response spectra as a combination of the site matched and soil response analyses results weighted in terms of the number of observhtions (earthquake records).
It then follows that the 84th percentile value of the logio pseudo-velocities is calculated as:
MSDLOGV = v + (s 2
)\ (Eq A6-15) and the conversion to velocity is:
MSDLOW (Eq A6-16)
MSDV = 10 (in/sec) l l
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