ML20126G915
| ML20126G915 | |
| Person / Time | |
|---|---|
| Site: | Summer  |
| Issue date: | 09/30/1992 |
| From: | Bombard T, Rajendran K SOUTH CAROLINA, UNIV. OF, COLUMBIA, SC |
| To: | |
| Shared Package | |
| ML20126G912 | List: |
| References | |
| 92-3, NUDOCS 9301040278 | |
| Download: ML20126G915 (17) | |
Text
- _ _ _ _ _ _ - _ _ _ - _ _ - _ _ _ _ _
TECHNICAL REPORT 92-3 SEISMIC At .iVITY NEAR THE V.C. SUMMER NUCLEAR STATION [
FOR T14E PERIOD JULY - SEPTEMBER 1992 BY PRADEEP TALWANI Principal Investigator Kusala Rajendran and Tate Bombard DEPARTMENT OF GEOLOGICAL SCIENCES UNIVERSITY OF SOUTIl CAROLINA COLUMBIA,SOUT11 CAROLINA 29208 CONTRACT NO. N574984 788'2882!Ea886 R PDH
- TECHNICAL REPORT 92-3 SEISMIC ACTIVITY NEAR THE V.C. SUMMER NUCLEAR STATION .l i
FOR THE PERIOD e
JULY -SEPTEMBER 1992 j 4
~i P
BY _;
PRADEEP TALWANI
- Principal Investigator DEPARTMENT OF GEOLOGICAL SCIENCES
- UNIVERSITY OF SOUTH CAROLINA--
' COLUMBIA, SOUTH CAROLINA' 29208- !
CONTRACr NO. N574984
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INTRODUCTION Analysis of the seismic activity near the V.C. Summer Nuclear Station in South Carolina between July 1 and September 30,1992 is presented in this report. During this period,9 events were recorded in the vicinity of Monticello Reservoir,2 of which were located. The largest magnitude recorded duiing this period was ML=1.0.
, This earthquake was located outside the reservoir.
SEISMIC NETWORK Earthquakes during this period were recorded on stations of Monticello Reservoir and South Carolina Seismic Network. The configuration of stations utilized to locate Monticello events is shown in Figure 1 and station coordinates ~ listed in Appendix 1. The operational status of the network is given in Appendix IL DATA ANALYSIS Hypocentral locations have been determined using the computer program HYPO 71 (Lee and Lahr,1972). The velocity model used in the earthquake locations is given in Appendix III. The format of the output is given in Appendix IV. The event magnitude was determined from the signal duration at JSC using the following relation:
M L= -1.83 + 2.04 Log D, where D is the signal duration (seconds).
An estimate of daily energy release was determined using a simplified magnitude (ML).cnergy (E) relation by Gutenberg and Richter (1956):
Logto E = 11.8 + 1.5 ML OBSERVED SEISMICITY DURING JULY SEl'TEMBER,1992 Seismicity around Monticello Reservoir was generally low during this period.
There was one event in August, and eight in September. Of these 9 cvents, 2 were located (Figure 2). The located events were of poor quality (C or D). The largest event in the quarter occurred on August 25 (17:04:57.66 UTC) and it had a magnitude M t= 1.0. This event occurred to the northwest of the lake and was not well located. However, it is included in the analysis due to the uncertainty _in location. The other located event of Mt = 0.8 (September 8,1992) occurred to the east of the reservoir. The remaining seven unlocated events were_of small magnitude (Mt = -0.4).
1
The long term decline in seismicity observed at Monticello_ Reservoir is continuing (Figure 3). The cumulative seismicity at Monticello Reservoir shows a relative flattening since 1985-86 (Figure 4).
CORRELATION OF WATER LEVEL WITil SEISMICITY Monticello Reservoir is a pumped storage facility. Any decrease in the reservoir level associated with power generation is recovered when water is pumped back into the reservoir. There can be normal variations up to five feet per day between maximum and minimum water levels. The water level has been monitored to see if there is any correlation between the daily or seasonal changes in the reservoir level and the local seismicity. Water levels are compared with seismicity in Figure 5.
The top panel shows the average water level; the error bars show the maximum and minimum water levels each day. The second panel shows the change in water level from day to day. The number of events per_ day and the log of energy released are shown in the lower histograms. These charts include all reported earthquakes listed in Appendices V and VI. The average water level, daily changes in water level, number of earthquakes and energy release are given in Appendix VII. No systematic correlation was observed between the seismicity and reservoir level fluctuations.
CONCLUSIONS The level of seismicity during the third quarter wr.s slightly lower, as compared to the previous quarter. The largest recorded magnitude was Mtp1.0. - Both of the located events lie outside of the reservoir. No systematic correlation was observed between the reservoir level fluctuations and the seismicity.
REFERENCES Gutenberg,It and Richter,C.F. (1956). Magnitude and energy of earthquakes, Ann.
Geof. 9,1 15.
Lee, W.H.K. and Lahr, J.C. (1972). A computer program for determining hypocenter, magnitude and first motion pattern of local earthquakes, revisions of HYPO 71, U.S. Geological Survey, Open File Report,100 pp.
4 2
Monticello Reservoir Seismic Network
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A Single component
$ 3 component Figure 1 Location of Monticello Reservoir area showing seismic stations used in locating seismicity.
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' O KILOHETERS 5 i i _i i i i Figure 2. Earthquakes located near Monticello Reservoir during the period July- -
September,1992 r 4
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1992 IM 1980 1982 1984 1986 1933 1990 Figure 4. ' Monthly seismicity (bars) and cumulative seismicity Gine) near -
Monticello Reservoir since impoundment.
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JULY / AUGUST / SEPTEMBER Figure 5 Comparison of daily lake leveh, changes in lake level, number of carthquakes and the log of energy release (ergs per day) at Monticello Reservoir. Error bars in the top panel indicate daily fluctuations in water level 7
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-i API'ENDIX I
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7 STATION LOCATIONS STATION LAT*N LONG'W ,
JSC 34 16.80' 81'15.60' .
001 34'19.91' 81 17.74' .
002 34 11.58' 81'13.81' ?
005 34'16.05' 81 20.05' 007 3P22.23' BF19.50' 010 34'20.18' Al *20.25' .
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4 .
4 8
APPENDIX 11 ,
SEISMIC STATION OPERATIONAL STATUS JULY 01 SEPTEMBER 30,1992 STATION PERCENT DOWNTIME MR01 10 MR02 - 4 ,
MR05 24 MR07 5 MRIO 6 Jsc o i
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f APPENDIX 111
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MONT.1 CELLO RESERVOIR - 3 VELOCTIY MODEl, p
,3 Vebcity Depth to top <
km km/sec l[
1.00 'O.00 5.40 0.03 ..
.i .
S.90 0.18 7
6.10 OA6 c!.
630 OS2 8.10 30.00
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A PPENDIX IV MONTICEll.O EARTHQUAKES HYPO 71 FORMAT Column 1 Date Column 2 Origin time (UTC) h.m.sec.
I Column 3 Latitude (N) degrees, min. _
Column 4 Longitude (W) degrees, min.
0 Column 5 Depth (km).
Column 6 Local duration magnitude.
Colurne 7 No. of station readings used to locate event. P and S arrivals from same stations are regarded as 2 readings.
~
Column 8 Largest azimuthal separation in degrees between stations.
Column 9 Epicentral distance in km to nearest station.
C Column 10 Root mean square error of time residuals in sec.
RMS = Ri 2/No, where Ri is the time residual for the ith station.
Column 11 Standard error of the epicenter in km*
Column 12 Standard error of the focal depth in km*,
Colunm 13 Quality of the epicentral location.
- Statistical interpretation of standard errors involves m imptions which may not be met hi earthquake locations. Therefore standard errors may not represent aaual error limits.
Note: If ERH or ERZ is blank, this means that it annot be computed, because of insufficient data.
11 I
_ a _..________ ________________ _ _ . _ _ _ _ _ _ . _ _ _ _ _ _ _ _ _ _ _ _ _ _ . _ _ _ _ _ _ _ _ __ _ _ _ _ . _ . _ _ _ . _ _ _ . _ _ _ _
_ l Appendix V
, MONTICELLO RESERVOIR EARTliQUAKES JULY-SEPTEMBER 1992 DATE ORIGIN LAT }J LollG W DEPTil MAG 110 GAP DMIl1 RMS ERll ERZ OM 920B25 17 4 57.66 34-24.50 81-24,40 0.69 1.02 7 333 8.6 0.23 5.4 D1 920908 1755 43.74 34-21.98 81-16.80 2.00 0.82 6 253 4.2 0.08 1.2 3.6 c1
)l e
9' -
a, 12
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f
= APPENDIX VI Events with S-P s 2.5 s recorded around Monticello Reservoir during July - September,1992 s
SLNO DATE STATION P Arrival S-P- Ep.Dist(km) DUR MAG Hr min sec SEC (S P)X8.5 SED 1 92 09 07 MR0'7 16:04 17.20 0.1 0.85 5 -0.4=
2 92 09 08 MR07 07:48 48,70 0.2 1.7 5 0.4 3 92 09 10 MR07 14:45 20.90 0.1 0.85 5 -0.4 4 92 09 10 MR07 15:46 27.70 0.1 0.85 5 -0.4 5 92 09 16 EC 15:38 53.10 0.1 0.85 5 -0.4 6 92 09 26 MR07 04:46 36.60 0.1 0.85 5 -0.4 7 92 09 28 JSC 22:46 07.90 0.1 0.85 5 -0.4 k
9 4
4 4
d 13
. Appendix VII 4
Maximum and minimum water levels, change in water level, number of earthquakes and log of energy release per day at Monticello Reservoir during July 1-September 30,1992. Dates are given in Julian Calender.
DATE WL (m_ax) WL (min) Average Chango # eqs Energy 183 424.2 423.5 424.0 0.068 0 0 184 424.3 423.1 423.9 0.316 0 0
. 185 424.2 422.8 423.6 0.0B 0 0 186 424.5 422.8 423.7 0.136 0 0 187 ~
424,9 422.8 423.8 0.674 0 0 188 425 423.5 424.5 0.998 0 0 189 424.7 _4 21 423.5 0.130 0 0 190 425 421.3 423.3 0.076 0 0 191 425 421.2 423.3 0.504 0 0 192 425 420.7 422.8 0.250 0 0 193 424.8 420.6 422.5 0.576 0 0 194 425 420.7 423.1 0.12 0 0 195 425 421.1 423.2 0.276 0 0 196 424.9 421 422.9 0.204 0 0 197 424.9 421.2 423.1 0.032 0 0 198 425 421.2 423.2 -0.324 0 0 199 424.9 421.8 423.5 -0.437 0 0 200 424.7 422.7 423.9 0.051 0 0 201 424.3 423.3 424.0 -0.16 0 0 202 425 423.3 424.1 0.544 0 0 203 425 421.4 423.6 0.32 0 0 204 425 421.6 423.3 -0.896 0 0 205 425 422.5 424.2 0.028 0 0 206 425 423.1 424.1 1.004 0 0 207 424.6 420.9 423.1 0.228 0 0 208 425 421.1 423.4 0.024 0 0 209 425 420.8 423.3 0.404 0 0 210 424.8 421 422.9 -0.212 0 0 211 425 420.9 423.1 -0.104 0 0 21_2 425 421.3 423.2 -0.048 0 0 213 425 421.6 423.3 -1.12 0 0 214 425 422.5 424.4 -0.038 0 0 215 424.5 424.4 424.5 0.222 0 0 216 425 423 424.2 0.952 0 0 217 425 420.8 423.3 0.588 0 0 218 425 421.1 423.9 -0.892 0 0 219 425 424.2 424.8 0.384 0 0 220 425 423.5 424.4 0.44 0 0 221 424.4 423.5 423.9 0.224 0 0 222 -424.6 422.9 423.7 -0.2 0 0
. 223 425 422.5 423.9 0.204 0 -0 224 424.7 422.5 423.7 -0.468 0 0 225 425 422.7 424.2 -0.24 0 0 226 425 423.6 424.4 0.056 0 0
-227 424.9 423.9 424.5 0.38 0 0 228 424.7 423.3 424.1 0.112 0 0 229 425 422.9 424.0 -0.24 0 0 14
-1 APPENDIX VII (cont'd):
230 425 423 424.2 0.62 0 0
.. 231 424.3 423.1 423.6 0.7 0 0 23P 425 423.3 424.3 0.172 0 0 233 425 423.9 424.5 0.032 0 0
', 234 425 424 424.5 0.304 0 0 235 424.6 423.6 424.2 -0.056 0 0 236 424.6 423.6 424.3 0.292 -0 0 237 425 424 424.5 0.236 0 0 238 425 423.5 424.3 0.104 i 13.33 239 425 423.5 424.4 -0.3 0 0 240 425 424.2 424.7 -0.150 0 0 241 425 424.7 424.9 0.682 0 0 -
242 424.8 422.7 424.2 _ -0.184 0 0 243 424.8 423.9 424.4 0.304 0 0 244 425 422.6 424.1 0.12 0 0 245 425 422.9 424.2 0.008 0 0 246 424.9 423.4 424.2 0.08 0 0 247 425 423 424.1 0 0 0 248 425 423 424.1 - -0.1 0 0 249 424.4 423.6 424.2 0.1 -0 0 250 424.8 423.6 424.3 0.3 0 0 251 _
424.3 423.6 424 0.2 1 11.19 252 425 422.9 424.2 -0.1 2 13.04 253 425 422.9 424.3 0.1 0 0 254 425 423.2 424.4 0.3 2 11.44 255 424.9 422.8 424.1 -0.1 0 0 256 424.9 423 424.2 0.3 0 0 257 424.8 423.9 424.5 0.1 0 -0 258 425 423.4 424.4 0.2 0 0 259 425 423.5 424.6 0.6 0 -0 260 425 422.4 424 0.3 1 ~ 11.19 261 424.9 422.6 423.7 -0.2 0 0 262 424.9 422.8 423.9 0.2 0 0 263 425 422.4 423.7 0.1 0 0 264 424.8 422.5 423.6 -1 0 0 265 424.8 422 424.6 1 0 0 266 424.9 422.1 423.6 -1.3 0 0 267 424.6 422.6 424.9 0.5 0 0 268 425 423.6 424.4 0.8 0 0 269 424.1 422.7 423.6 0.4 0 0 270 424.3 422.6 424 0.2 1 11.19 271 424.2 422.8 423.8 0.1 0 0 272 424.6 422.5 423.7 -0.9 1 11.19 273 425 422.9 424.6 0.1 0 0
,.- 274 424.9 424.1 424.5 0 0 1
_ _ _ _ -- -. - - .--