ML20094C459
| ML20094C459 | |
| Person / Time | |
|---|---|
| Site: | Summer  |
| Issue date: | 03/31/1995 |
| From: | Talwani P SOUTH CAROLINA, UNIV. OF, COLUMBIA, SC |
| To: | |
| Shared Package | |
| ML20094C444 | List: |
| References | |
| 95-1, NUDOCS 9511020226 | |
| Download: ML20094C459 (15) | |
Text
.
4 TECHNICAL REPORT 95-1 SEISMIC ACTIVITY NEAR THE V.C. SUMMER NUCLEAR STATION FOR THE PERIOD JANUARY - MARCH,1995 BY PRADEEP TALWANI Principal Investigator DEPARTMENT OF GEOLOGICAL SCIENCES UNIVERSITY OF SOUTH CAROLINA COLUMBIA, SOUTH CAROLINA 29208 CONTRACT NO. N622702 et 9511020226 951025 DR ADOCK 05000395 PDR
d i
TECHNICAL REPORT 95-1 4
SEISMIC ACTIVITY NEAR THE i
V.C. SUMMER NUCLEAR STATION i
4 4
5 FOR THE PERIOD 1
JANUARY - MARCH,1995 4
i BY Ij..
PRADEEP TALWANI j
Principal Investigator
}-
and Arleen A.H. West i
DEPARTMENT OF GEOLOGICAL SCIENCES UNIVERSITY OF SOUTH CAROLINA COLUMBIA, SOUTH CAROLINA 29208 CONTRACT NO. N622702
O INTRODUCTION Analysis of the seismic activity near the V.C. Summer Nuclear Station in South Carolina between January 1 and March 31,1995 is presented in this report. During this quarter, five events were recorded in the vicinity of the Monticello Reservoir, all of which were located and were of relatively small magnitude (< 1.0).
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 I. The operational status of the network is given in Appendix II.
DATA ANALYSIS Hypocentrallocations 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 (M ).
L energy (E) relation by Gutenberg and Richter (1956):
Logw E = 11.8 + 1.5 Mt OBSERVED SEISMICITY DURING JANUARY-MARCH,1995 Seismicity around Monticello Reservoir was low during the first quarter of 1995. Five events were recorded and located (Figure 2). All events for the quarter were shallow and varied in depth between 0.1 and 1.5 km. The largest event occurred on January 31, 1995 at 09:34:12 UTC and had a duration magnitude of 0.73 (Appendix V). Three events occurred in the month of January with the largest event of the quarter on January 31, 1995 (Appendix V). Two events occurred on March 3 and March 24,1995 (Appendix V).
All events were located on the western flank of the reservoir, four between MR07 and MR10 and the fifth to the south between MR10 and MR05 (Figure 2). All of the event locations were of fair quality (Appendix V). The long term decline in seismicity observed at Monticello Reservoir is continuing (Figure 3) and the cumulative seismicity has shown relative flattening since 1985-86 (Figure 4).
1
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 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 Appendix V. The average water level, daily changes in water level, number of earthquakes and energy release are given in Appendix VL No systematic correlation was observed between the seismicity and reservoir level fluctuations.
CONCLUSIONS Seismicity during the first quarter of 1995 was low and occurred between Stations MR07 and MR10, with the exception of an event further to the south.
No systematic correlation was observed between the reservoir level fluctuations and the seismicity.
REFERENCES Gutenberg, B. 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.
2
i I
I l
Monticello Reservoir Sub-Network l
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l l
l 0
i 34.4 l
MR07 I
l MRIO MR01 i
0 34.3
+
MR05 JSC 5.0km I
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I 34.2 MR02 A I
I I
81.4 81.3 81.3 l
A Single component
$ 3 component Figure 1.
Location of the Monticello Reservoir sub-network stations l
l 3
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Monticello Reservoir Seismicity
-81 23.O' 22.O' 21.O' 20.O' 19.O' 18.O' 17.O' 16.O' 15.O' i
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Figure 2.
Events located near Monticello Reservoir during the period January - March 1995 (stars).
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4 1650 MONTHLY SEISMICITY 800 --
700 --
t us E 600 --
30 500 --
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3 400 --
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S 200 --
100--
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i 1977 1970 1981 1983 1985 1987 1989 1991 1993 1995 t
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Figure 3.
Earthquakes between impoundment and March,1995.
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b CUMULATIVE SEISMICITY
-- 8000 t
-- 7000
-- 6000 uh us M<
-- 5000 3 r
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i 1977 1979 1981 1983 1985 1987 1989 1991 1993 1995 i
t Figure 4.
Cumulative seismicity near Monticello Reservoir since impoundment.
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g423 l422 421 1 7 13192531374349556167737985 l
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7 13 19 25 31 37 43 49 55 61 67 73 79 85 7 25-P3.20-i 15-5 g 10 -
85-i 0
1 7 13 19 25 31 37 43 49 55 61 67 73 79 85 JANUARY 1995 / FEBRUARY 1995 / MARCH 1995 Figure 5.
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.
7
.. _ _ _. _ ~. _ _.... _ _.. _.. _.
1 i
1 APPENDIXI
. STATION LOCATIONS i
i l
STATION LAT N LONG*W 4
JSC 34 16.80' 81*15.60' MR01 34*19.91' 81 17.74' a
MR02 34 11.58' 81 13.81' 4
M.R05 34*16.05' 81 20.05' MR07 34 22.23' 81 19.50' MR10 34 20.18' 81 20.25' e
e' 8
APPENDIX II SEISMIC STATION OPERATIONAL STATUS
- JANUARY 1 - MARCH 31,1995 STATION PERCENT DOWNTIME MR01 8.9 MR02 8.9 MR05 3.3 MR07 3.3 MR10 0.0 JSC 0.0 NOTE:
MR01 power off at relay tower December 30,1994 - January 9,1995.
9
l l
'APPENDIXIII MONTICELLO RESERVOIR-VELOCITY MODEL
- Velocity Depth to top km/sec km 1
1.00 0.00 5.40 0.03 5.90 0.18 6.10 0.46 6.30 0.82
~ 8.10 30.00 4
10
.=.....
APPENDIXIV MONTICELLO EARTHQUAKES HYPO 71 FORMAT Column 1
Date Column 2
Origin time (UTC) h.m.sec.
Column 3 Latitude (N) degrees, min.
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 R is 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.
- Statistical interpretation of standard errors involves assumptions which may no 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.
11
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e APPENDIX V MONTICELLO RESERVOIR EARTHQUAKES JANUARY - MARCH,1995 DATE ORIGIN LAT N LONG W DEPTH MAG NO GAP DMIN RMS ERH ERZ Q M 950104 0046 18.89 34-20.28 81-19.54 1.51
-0.86 8 124 1.1 0.05 0.4 0.6 B 1 950131 0934 12.27 34-21.10 81-20.35 1.21 0.73 8 217 1.7 0.06 0.5 0.8 C 1 950131 1000 29.72 34-21.22 81-20.35 1.21
-0.86 8 220 1.9 0.09 0.8 1.5 C 1 950303 1100 01.03 34-18.95 81-20.39 0.14
-0.86 4 353 2.3 0.01 C1 950324 0123 23.71 34-21.40 81-18.79 0.83
-0.40 6 185 1.9 0.01 0.2 1.1 C 1 e
12
~
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 January 1 - March 31,1995. Dates are given in Julian Calendar.
J.DATE WL (max) WL(min) WL (avg)
WL (ch)
- of eqs Energy 1
424.7 422.9 423.8 0.3 0
0 2
424.4 422.9 423.9 0.1 0
0 3
424.8 423.9 424.4 0.5 0
0 4
4 424.7 424 3 424.5 0.1 1
10.51 5
424.8 423
-423.7
-0.8 0
0 6
424.9 423 424.4 0.7 0
0 7
425 423.4 424
-0.4 0
0 2
8 423.7 423.4 423.4
-0.6 0
0 9
424.8 423.7 424.4 1
0 0
10 424.1 423.8 424.1
-03 0
0 11 424.2 423.9-424
-0.1 0
0 12 424.5 423.9 424 0
0 0
1.
13 424.4 423 423.6
-0.4 0
0 14 425 422.5 423.6 0
0 0
)
15 423.7 422.5 423.5
-0.1 0
0 L
16 423.7 423.7 423.7 0.2 0
0 17 423.7 423.7 423.7 0
0 0
18 423.7 423.6 423.7 0
0 0
19 423.8 423.4 423.5
-0.2 0
0 20 423.4 423.2 423 3
-0.2 0
0 21 424 423.2 423.7 0.4 0
0 22 424.5 423.7 424.4 0.7 0
0 23 424.9 424.5 424.7 03 0
0 24 424.5 423.3 423.8
-0.9 0
0 25 424.8 424 4243 0.5 0
0 26 424.9 424.4 424.7 0.4 0
0 27 424.7 423.7 424.1
-0.6 0
0 28 423.9 423.7 423.8
-03 0
0 29 424.3 423.8 424 0.2 0
0 30 424.9 423.1 423.9
-0.1 0
0 31 424.7 423.5 423.8
-0.1 2
23.41 32 424.8 424 424.4 0.6 0
0 33 423.9 423.9 423.9
-0.5 0
0 34 423.9 423.6 423.7
-0.2 0
0 35 424.4 423.6 423.5
-0.2 0
0 36 424.4 424.1 424.2 0.7 0
0 37 425 423.6 424 3 0.1 0
0 38 424.9 424.6 424.8 0.5 0
0 39 424.8 423 424.2
-0.6 0
0 40 424.7 423 423.9
-03 0
0 41 424.7 424.1 424 3 0.4 0
0 42 424.7 423.6 424
-03 0
0 43 424.4 423.6 424.2 0.2 0
0 44 424.7 424.4 424.5 0.3 0
0 45 424.7 424.4 424.5 0
0 0
13
APPENDIX VI (continued)
J.DATE WL (max) WL(min) WL (avg)
WL (ch)
- of eqs Energy 46 424.7 424.2 424.4
-0.1 0
0 47 424.6 424.1 424.2
-0.2 0
0 48 425 423.8 424.2 0
0 0
49 423.9 423.8 423.9
-03 0
0 50 423.9 423.9 423.9 0
0 0
51 423.9 423.9 423.9 0
0 0
52 424.2 423.9 424.1 0.2 0
0 53 424.9 423.8 424.1 0
0 0
54 424 423.7 423.8
-03 0
0 55 424.2 423.7 424 0.2 0
0 56 423.9 422.9 423.7
-03 0
0 57 423.6 422.9 4233
-0.4 0
0 58 424.7 423.5 423.8 0.5 0
0 59 424.4
- 423.5 423.9 0.1 0
0 60 424.4 423.5 423.9 0
0 0
61 423.5 423.4 423.5
-0.4 0
0 62 423.4 423 423.2
-03 1
10.51 63 423.4 423 423.2 0
0 0
64 423.4 423.1 423.3 0.1 0
0 65 423.8 423.4 423.6 0.3 0
0 66 423.8 423.4 423.6 0
0 0
67 423.8 422.7 4233
-03 0
0 68 424.5 422.5 423.1
-0.2 0
0 69 423.4 421.2 422
-1.1 0
0 70 4223 421 3 421.9
-0.1 0
0 71 422.8 421.8 422.3 0.4 0
0 72 423.7 422.8 423.6 13 0
0 73 424.3 423.5 423.7 0.1 0
0 74 423.6 423.1 4233
-0.4 0
0 75 423.9 423.1 423.8 0.5 0
0 76 424.4 423 423.7
-0.1 0
0 77 423.8 423 423.6
-0.1 0
0 78 423.7 423.4 423.7 0.1 0
0 79 423.7 423.7 423.7 0
0 0
80 424.1 423.7 424 0.3 0
0 81 424.3 423 423.8
-0.2 0
0 82 423 421.1 422.3
-1.5 0
0 83 423.9
'421 3 423.4 1.1 1
11.19 84 4243 423.4 423.9 0.5 0
0 85 423.8 423.5 423.7
-0.2 0
0 86 424.8 423.7 424 3 0.6 0
0 87 424.9 423.7 424.4 0.1 0
0 88 423.9 423.4 423.6
-0.8 0
0 89 424.1 423.5 423.9 0.3 0
0 90 424.7 424 424.6 0.7 0
0 14