ML20094C469
| ML20094C469 | |
| Person / Time | |
|---|---|
| Site: | Summer  |
| Issue date: | 06/30/1995 |
| From: | Talwani P SOUTH CAROLINA, UNIV. OF, COLUMBIA, SC |
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| References | |
| 95-2, NUDOCS 9511020232 | |
| Download: ML20094C469 (14) | |
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i i
t TECHNICAL REPORT 95-2 1
4 SEISMIC ACTIVITY NEAR THE V.C. SUMMER NUCLEAR STATION 4
4 i
4 FOR THE PERIOD APRIL-JUNE,1995 BY PRADEEP TALWANI Principal Investigator DEPARTMENT OF GEOLOGICAL SCIENCES UNIVERSITY OF SOUTH CAROLINA COLUMBIA, SOUTH CAROLINA 29208 CONTRACT NO. N622702 9511020232 951031 PDR ADOCK 05000395 R
TECHNICAL REPORT 95-2 SEISMIC ACTIVITY NEAR THE V.C. SUMMER NUCLEAR STATION FORTHE PERIOD
]
APRIL-JUNE,1995 BY PRADEEP TALWANI Principal Investigator and Arleen A. H. West j
DEPARTMENT OF GEOLOGICAL SCIENCES UNIVERSITY OF SOUTH CAROLINA COLUMBIA, SOUTH CAROLINA 29208 CONTRACT NO. N622702
INTRODUCTION Analysis of the seismic activity near the V.C. Summer Nuclear Station in South Carolina between April 1 and June 30,1995 is presented in this report. During this penod, forty-nine events were recorded in the vicinity of the Monticello Reservoir. All forty-nine events were located and ranged in magnitude from -0.6 to 2.5.
SEISMIC NETWORK Earthquakes during this period were recorded on stations of Monticello Reservoir and South Carolina Seismic Networks. The configuration of stations utilized to locate Monticello Reservoir events is shown in Figure 1 and station coordinates are listed in Appendix L The operational status of the network is given in Appendix II.
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 HYPO 71 output is given in Appendix IV. The event magnitude was determined from the signal duration at JSC using the following relation:
M = -1.83 + 2.04 Log D, t
where D is the signal duration (seconds).
An estimate of daily energy release was determined using a simplified magnitude (ML).
energy (E) relation by Gutenberg and Richter (1956):
Logio E = 11.8 + 1.5 Mt OBSERVED SEISMICITY DURING APRIL-JUNE,1995 Seismicity around Monticello Reservoir was moderate during the second quarter of 1995. Forty-nine events were recorded and located (Figure 1). All events for the quarter were shallow and varied in depth between 0.09 and 3.64 km. The largest event occurred on April 18,1995 at 14:36:46 UTC and had a duration magnitude of 2.5 (Appendix V). A total of forty events occurred in April,1995 with thirteen in a 21 hour2.430556e-4 days <br />0.00583 hours <br />3.472222e-5 weeks <br />7.9905e-6 months <br /> burst on April 18, 1995 (Appendix V). Six events occurred in the month of May and three occurred in June (Appendix V). By the end of the quarter the burst of activity had subsided. The majority of the events were located in the central area of the reservoir between stations MR07 and MR10. The remaining events occurred in two groups, one between stations MR01 and MR10, the other west of station MR10 (Figure 1). One event located in the center of the reservoir with a 0.3 magnitude was an A quality location (Appendix V).
Twenty event locations were of good quality (B) with the remaining twenty-eight of fair quality (C) (Appendix V).
1
The long term decline in seismicity observed at Monticello Reservoir is continuing (Figure 2) and the cumulative seismicity has shown relative flattening since 1985-86 (Figure 3).
CORRELATION OF WATER LEVEL WITH 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 mimmum 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 4. 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 Appendix V. The average water level, daily changes in water level, number of earthquakes and energy release are given in Appendix VI. No systematic correlation was observed between the seismicity and reservoir level fluctuations.
CONCLUSIONS Seismicity during the second quarter of 1995 was moderate and occurred generally in J
the central section of the reservoir, with the exception of the seven events west of station MR10. No systematic correlation was observed between the reservoir level fluctuations and the seismicity.
i REFERENCES Gutenberg, B. and Richter, C.F. (1956). Magnitude and energy of earthquakes, Ann.
Geof. 9,1-15.
1 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.
2
0 Monticello Reservoir Sub-Network Earthquakes: April 1 - June 30,1995
- 25
- 20
- 15 W 81:10 l
l I
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- 20 R10 (L'
A JSC MR05
- 15 5.0 kms MR02A l
l I
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l N 34:10 Figure 1.
Station locations of the Monticello Reservoir sub-network.
Earthquakes located near Monticello Reservoir during the period April - June,1995 (stars).
3
4 1650 MONTHLY SEISMICITY 800 --
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t t
l 700 --
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600 --
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k 200--
100--
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1977 1979 1981 1983 1985 1987 1989 1991 1993 1995 i
Figure 2.
Earthquakes between impoundment and June,1995.
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L CUMULATIVE SEISMICITY
-- 8000 I
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Figure 3.
Cumulative seismicity near Monticello Reservoir since impoundment.
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a 91 101 111 121 131 141 151 161 171 181 APRIL 1995
/
MAY1995
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JUNT1995 Figure 4.
Comparison of daily lake level, changes in lake level, number of earthquakes and the log of energy release in ergs per day at Monticello Reservoir. Error bars in the top panel indicate daily fluctuations in water level.
6
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[
1 APPENDIXI STATION LOCATIONS -
STATION LAT N LONG*W JSC 34 16.80' 81*15.60' i
MR01 34 19.91' 81 17.74' MR02 34 11.58' 81 13.81' MR05 34 16.05' 81 20.05' MR07 34 22.23' 81*19.50' MR10 34*20.18' 81*20.25' d
a L
4 7
APPENDIX II SEISMIC STATION OPERATIONAL STATUS 5'
APRIL 1 -JUNE 30,1995 i
STATION PERCENT DOWNTIME i
J MR01 0.0
~ MR02 0.0 MR05 0.0 -
i
.MR07 2.2 MR10 6.6 JSC' O.0
)
8
APPENDIXIII MONTICELLO RESERVOIR VELOCITY MODEL Velocity Depth to top km/sec km 1.00 0.00 5.40 0.03 5.90 0.18 6.10 0.46 6.30 0.82 8.10 30.00 1
i I
9 i
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APPENDIX IV MONTICELLO EARTHQUAKES
^
HYPO 71 FORMAT 4
Column 1
Date Column 2
Origin time (UTC) h.m.sec.
Column 3 Latitude (N) degrees, min.
J Column 4
Longitude (W) degrees, min.
Column 5
Depth (km).
Column 6
Local duration magnitude.
Column 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.
Column 10 Root mean square error of time residuals in sec.
RMS = R 2/No, where Ri s the time residual for the ith i
i station.
Column 11 Standard error of the epicenter in km*.
Column 12 Standard error of the focal depth in km'.
Column 13 Quality of the epicentral location.
j l
- Statisticalinterpretation of standard errors involves assumptions which may not
' be met in earthquake locations. Therefore standard errors may not represent actual error limits.
Note: If ERH or ERZ is blank, this means that it cannot be computed, because of insufficient data, j
G 10
m A
g m
s e
APPENDIX V MONTICELLO RESERVOIR EARTHQUAKES APRIL - JUNE,1995 DATE ORIGIN LAT N LONG W DEPTH MAG NO GAP DMIN RMS ERH ERZ Q M 950407 1754 22.19 34-21.29 81-19.17 1.02
-0.60 6 163 1.8 0.02 0.2 0.9 B 1 950407 1940 11.81 34-21.15 81-20.35 2.89
-0.60 6 218 1.8 0.03 0.4 0.3 C 1 950416 0207 59.13 34-19.65 81-18.79 2.95 0.12 6 157 2.4 0.04 0.6 0.9 B 1 950417 0512 42.29 34-21.08 81-20.00 0.19 0.91 10 187 1.7 0.05 0.3 0.6 C 1 950417 1804 44.28 34-21.07 81-20.02 1.27 0.37 6 188 1.7 0.04 0.6 0.8 C 1 4
950418 0257 20.87 34-21.05 81-19.67 0.42 0.37 6 158 1.8 0.01 1.3 2.5 C 1 950418 0458 22.94 34-21.36 81-19.82 2.04 1.88 9 180 1.7 0.04 0.4 0.5 C 1 950418 0802 43.83 34-21.05 81-19.51 0.45 0.21 6 145 2.0 0.04 0.3 1.4 B 1 950418 1101 00.57 34-21.12 81-18.96 0.42 0.87 12 162 2.2 0.09 0.6 2.0 B 1 950418 1436 46.59 34-21.31 81-19.57 1.47 2.48 12 157 1.7 0.07 0.4 0.7 B 1 950418 1439 26.09 34-21.07 81-19.45 0.28
-0.24 7 141 2.1 0.04 0.4 1.2 B 1 950418 1753 39.66 34-21.07 81-20.04 1.61 0.01 8 190 1.7 0.04 0.4 0.5 C 1 950418 1826 33.49 34-21.37 81-19.80 2.71 1.24 12 178 1.7 0.06 0.4 0.4 B 1 950418 1944 30.68 34-21.07 81-20.19 1.33 1.24 8 203 1.7 0.03 0.3 0.4 C 1 950418 1944 48.98 34-21.05 81-19.77 0.65 0.01 6 166 1.8 0.01 0.2 0.4 B 1 950418 1947 21.91 34-21.03 81-19.76 0.59
-0.86 6 164 1.7 0.01 0.1 0.3 B 1 950418 2122 23.33 34-21.09 81-20.35 3.00
-0.86 6 217 1.7 0.10 1.6 1.3 C 1 950418 2301 34.59 34-20.98 81-19.58 0.09 0.01 8 148 1.8 0.05 0.2 0.8 B 1 950419 0053 15.82 34-21.05 81-19.93 0.71 1.44 9 180 1.7 0.04 0.5 0.8 B 1 950420 1234 04.92 34-21.22 81-19.14 0.68
-0.40 6 163 1.9 0.01 1.1 3.0 C 1 950420 1303 10.32 34-21.04 81-19.65 0.26 0.44 9 156 1.8 0.02 0.3 0.6 B 1 950420 1306 03.83 34-20.90 81-19.32 0.22
-0.11 8 134 2.0 0.07 0.2 0.7 B 1 950420 2247 09.86 34-21.22 81-19.56 1.95 0.01 6 154 1.9 0.00 0.1 0.1 B 1 950421 0124 32.39 34-20.38 81-17.21 0.82 0.82 8 205 4.7 0.03 0.2 0.9 C 1 950423 0154 52.35 34-20.28 81-21.67 3.64 1.02 6 278 2.2 0.08 1.4 1.0 C 1 950423 0216 19.40 34-20.53 81-20.63 0.91 0.82 6 251 0.9 0.01 0.1 0.1 C 1 950423 0230 42.34 34-20.91 81-20.69 3.00 0.99 12 223 1.5 0.10 0.7 0.6 C 1 950423 0236 44.19 34-20.49 81-20.35 1.07
-0.11 6 217 0.6 0.05 0.8 0.6 C 1 950423 0355 07.67 34-20.28 81-21.42 2.23 0.12 6 273 1.8 0.05 0.9 0.7 C 1 950423 0950 31.50 34-23.90 81-20.77 3.00 0.95 6 249 1.5 0.07 1.1 0.8 C 1 950423 1845 59.47 34-21.05 81-20.01 1.36
-0.40 6 186 1.6 0.04 0.5 0.7 C 1 950423 1951 04.07 34-21.08 61-19.99 1.71 1.09 6 186 1.7 0.01 0.2 0.2 C 1 950425 0936 37.43 34-21.19 81-20.08 1.68
-0.40 4 197 1.9 0.00 C1 950427 0810 45.65 34-19.87 81-22.27 3.17
-0.11 6 285 3.2 0.05 1.1 1.0 C 1 950427 1740 14.55 34-20.02 81-21.96 3.56 0.82 6 281 2.6 0.06 1.1 0.8 C 1 950427 2015 55.75 34-21.15 81-19.66 1.89
-0.24 6 161 2.0 0.02 0.3 0.4 B 1 950427 2202 36.14 34-20.03 81-21.25 1.33 0.95 8 227 1.6 0.06 0.5 0.6 C 1 950427 2211 32.92 34-21.39 81-18.99 0.28
-1.83 4 284 3.0 0.01 C1 950427 2211 34.30 34-21.95 81-18.90 0.53
-0.86 4 302 3.9 0.05 C1 950427 2213 14.12 34-20.28 81-22.28 2.41
-0.24 6 288 3.1 0.08 1.3 1.5 C 1 950501 2206 38.22 34-21.15 81-19.78 0.30 0.68 12 170 1.9 0.04 0.4 0.8 B 1 950505 1708 22.22 34-20.01 81-17.84 0.99
-0.60 4 350 0.2 0.05 C1 950509 0101 47.87 34-20.36 81-17.38 0.55
-0.24 8 201 1.0 0.02 0.2 0.3 C 1 950509 0811 38.33 34-19.77 81-19.40 3.00
-0.40 6 167 1.5 0.06 0.8 0.9 B 1 950520 2300 28.39 34-21.12 81-19.84 0.51 0.91 12 174 1.9 0.05 0.3 0.8 B 1 l
950526 2146 02.26 34-21.07 81-19.77 0.92
-0.24 6 167 1.8 0.01 0.2 0.5 B 1 950601 1349 44.13 34-19.90 81-19.32 1.95
-0.24 8 155 1.5 0.03 0.2 0.3 B 1 950602 1823 13.90 34-19.70 81-18.46 2.27 0.29 10 89 1.2 0.08 0.4 0.6 A 1 950622 1727 41.88 34-19.91 81-21.66 0.58
-0.11 6 276 2.2 0.02 0.3 0.7 C 1 11
j
~_
APPENDIX VI Maximum and. minimum water levels, change in water level, number of earthquakes and log of energy release per day at 'Monticello Reservoir during April 1 - June 30,1995. Dates are given in Julian Calendar.
l*
j J.DATE WL (max) WL (min) WL (avg)
WL (ch)
- of eqs Energy l
91 424.5 423.5 424 03 0
0 92 424.9 423.8 424.6 0.1 0
0 l
93 424.9 422.5 423.6
-1 0
0
[
94 424.7 422.5 423.8 0.2 0
0 95 424.8 423.1 423.9 0.1 0
0 l
96 424.9 423.1 423.9 0
0 0
97 424.5 422.8 423.6
-03 2
21.8 98 424.5 423 423.8 0.2 0
0 99 424.1 423.2 423.7
-0.1 0
0 100 424.6 420.5 422.9
-0.8 0
0 101 423.9 420.9 423.4 0.5 0
0 102 424.4 423.8 424.1 0.7 0
0 103 424.6 423.7 424.4 03 0
0 104 424.5 423.4 423.9
-0.5 0
0 105 424.7 422.6 423.8
-0.1 0
0 106 424.1 422.6 423.7
-0.1 1
11.97 107 424.7 423.5 424.2 0.5 2
25.52 108 424.8 421.7 423.7
-0.5 13 161.94 109 425 422 423.6
-0.1 1
13.96 110 424.8 420.5 423
-0.6 4
35.92 111 425 420.8 423.8 0.8 1
13.04 112 424.2 422.5 423.6
-0.2 0
0 113 424.8 422.6 424.1 0.5 8
101.1 114 424.6 424.1 424.4 0.3 0
0 115 424.6 424.4 424.6 0.2 1
11.19 116 425 424 424.5
-0.1 0
0 117 424.7 424 424.3
-0.2 7
80.34 118 424.4 423.6 424
-03 0
0 j
119 424.7 423.8 424.2 0.2 0
0 120 424.9 423.5 424.2 0
0 0
121 424.9 422.8 423.9
-03 1
12.82 122 425 422.9 424 3 0.4 0
0 123 424.6 423.9 424.2
-0.1 0
0 124 424.7 423.9 424.5 03 0
0 125 424.7 423.9 424 3
-0.2 1
10.9 126 424.7 423.6 4243 0
0 0
127 424.8 423.6 424.2
-0.1 0
0' 128 424.9 423.9 424.5 0.3 0
0 129 424.8 423.2 424.1
-0.4 2
22.63 130 424.9 423.6 424.3 0.2 0
0 131 424.9 421.9 423.9
-0.4 0
0 132 424.9 422.2 423.9 0
0 0
133 424.8 422 4233 0
0 0
l 134 424.9 422 423.7 0.4 0
0 l
135 425 421.2 423.5
-0.2 0
0 136 425 421.4 423.7 0.2 0
0 12
APPENDIX VI (continued)
J.DATE WL (max) WL (min) WL (ave)
WL (ch)
- of eqs Energy 137 425 421.4 423.2
-0.5 0
0 138 425 4213 423.2 0
0 0
139 425 421.4 424.1 0.9 0
0 140 424.9 423.9 424.4 0.3 1
13.16 141 424.8 423.9 424.4 0
0 0
142
'424.9 423.7 424.5 0.1 0
0 143 424.9 423 424.2
-03 0
0 144 424.9 421.1 4233
-0.9 0
0 145 425 421 3 423.2
-0.1 0
0 146 424.5 421.4 423
-0.2 1
11.64 147 424.4 421.4 423.7 0.7 0
0 148 424 3 423.4 423.9 0.2 0
0 149 424.7 423.5 424.1 0.2 0
0 150 424.8 422.9 423.9
-0.2 0
0 151 425 423.1 4243 0.4 0
0 152 424.5 422.7 423.8
-0.5 1
11.64 153 424.9 422.9 423.9 0.1 1
12.24 154 424.8 423.4 424.1 0.2 0
0 155 424.6 423.2 423.9
-0.2 0
0 156 424.6 423.5 424.4 0.5 0
0 157 424.7 424.2 424.5 0.1 0
0 158 424.9 421.4 423.7
-0.8 0
0 159 425 421.5 423.3
-0.4 0
0 160 425 421.8 423.5 0.2 0
0 161 425 422.2 424 0.5 0
0 162 425 423 424.1 0.1 0
0 163 425 423.8 424.6 0.5 0
0 164 424.9 424.2 424.7 0.1 0
0 165 424.6 423.5 424.2
-0.5 0
0 166 424.9 422.1 423.8
-0.4 0
0 167 424.9 422.6 424 0.2 0
0 168 425 422.3 423.7
-03 0
0 169 424.6 4223 423.3
-0.4 0
0 170 424.9 422.6 424 0.7 0
0 171 424.7 422.9 423.9
-0.1 0
0 172 425 423 424 0.1 0
0 173 424.9 421.8 423.7
-03 1
11.64 i
174 425 422.2 423.2
-0.5 0
0 175 424.8 422.4 423.8 0.6 0
0 176 424.4 423.1 423.8 0
0 0
177 425 422.6 423.6
-0.2 0
0 178 424.9 422.5 423.7 0.1 0
0 179 425 422.7 424.4 0.7 0
0 180 424.7 423.7 424.4 0
0 0
181 424.7 422.4 423.8
-0.6 0
0 13