ML20101L953
| ML20101L953 | |
| Person / Time | |
|---|---|
| Site: | Summer  |
| Issue date: | 03/31/1992 |
| From: | Rajendran K, Talwani P SOUTH CAROLINA, UNIV. OF, COLUMBIA, SC |
| To: | |
| Shared Package | |
| ML20101L952 | List: |
| References | |
| 92-1, NUDOCS 9207070429 | |
| Download: ML20101L953 (17) | |
Text
. - . _ . .. . . . - -- . - .- --
e TECHNICAL REPORT 92-1 3
SEISMIC ACTIVITY NEAR THE V.C. SUMMER NUCLEAR STATION FOR THE PERIOD JANUARY -MARCH 1992 BY PRADEEP TALWANI Principal Investigator DEPARTMENT OF GEOLOGICAL SCIENCES UNIVERSITY OF SOUTH CAROLINA COLUMBIA, SC 29200 y CONTRACT NO. N574984 i
l 1
TECHNICAL REPORT 92-1 l SEISMIC ACTIVITY NEAR THE i
V.C. SUMMER NUCLEAR STATION 1 l
FOR THE PERIOD
-JANUARY-MARCH 1992 BY PRADEEP TALWANI and KUSALA' RAJENDRAN
-DEPARTMENT OF GEOLOGICAL SCIENCES UNIVERSITY OF SOUTH CAROLINA -
COLUMBIA, S.C.29208 k
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INTRODUCTION Analysis of the seismic activity near the V.C. Summer Nuclear Station in South Carolina for the period January-March 1992 is presented in this report. During this period,13 events were recorded in the vicinity of Menticello Reservoir. Three i events were located and they lie in the central part of the reservoir. Most of the activity occurred in a sequence during February 25 26. The largest event recorded was of magitude M t= 1.0 and it occurred on February 25 (13:?7:42.78 UTC). This was the only event of Mt 21.0 during this quarter. It was followed by 10 aftershocks, of ,
i which only one was locatable. Other than this activity, the seismicity during this quarter was of a very low level.
SEISMIC NETWORK 1 l
Earthquakes during this perloo 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 are listed in Appendix 1. The network was fully operational during most of this quarter although stations MR01 and MR02 where not fully operational during brief periods.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 output is given in Appendix IV. The event magnitude was determined from the signal duration at JSC using the following relation:
Mt = -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 (M L). energy (E) relation by Gutenberg and Richter (1956):
Logw E = 11.8 + 1.5 ML OBSERVED SEISMICITY DURING JANUARY-MARCH l During this period 13 earthquakes were recorded, of which 3 were located (Figure 2; l Appendix V). All of the located events were of B quality. Eleven of the 13 events l
1
recorded during this period occurred in a sequence during February 25-26. The largest event of this quarter ( Mt =1.0 ) which occurred on February 25 (13:37:42.78 UTC) was the main event of this sequence. The only other locatable event in this sequence occurred on February 26, and was located very close to the earlier one. The remaining events of this sequence were generally of short duration with an S-P tirae of 0.5-0.7see at MR07 (Appendix VI).
1 The long term decline in seismicity observed at Monticel% is continuing
( Figure 3). The seismicity at Monticello seems to have leveled off since 1985-1986 (Figure 4).
1 CORRELATION OF WATER LEVEL WITH SEISMICITY I
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 ncrmal variations up to five feet per day between muimum 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 J.ay. 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 VIL No systematic correlation was observed between the seismicity and reservoir level fluctuatione CONCLUSIONS The level of seismicity recorded during the first quarter of 1992 was slightly lower, compared to the previous quarter. The largest event occurred on February 25, followed by one locatable afterchock and 9 smaller ones. 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.
t Geological Survey, Open-File Report,100 pp.
l 2
l l
Monticello Reservoir Seismic Network i
___ 34.4 s;
'N MR10 MR01
_ 34.3
+
MR05 JSC i
5.0 km l I
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_ 34.2 MR02 A I I - ._I 81.4 81.3 81.2
' A Single component l
$ 3 component Figure 1 Location of Monticello Reservoir area showing seismic stations used in locating seismicity.
3
e 22.0 21.0 B1 s
20.0 19.0 18.0 17.0 16 0 1 1 1 t t l t i i f f I I i ,
_ _24.n
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- _23.0
- _22.5
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- _17.5
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- _16.5
- _1E.0 j _ _15.5 l
i i i i i i i i i i i i e i 34 L 0- KILOMETERS S-t f f I I t
Figure 2. Earthquakes lccated near Monticello Reservoir during the period
. January-March,1992 4
- ~ - .
I 900 -- l s i 800--
i 700 --
i 600 -- -
m '
h 500 --
E m
H 400 -- ,
8 300 -- ,
i a
200 --
o_
1977 La 1981 kM i y_. 9 _ 9 .. 4 1991
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.1979 1983 1985 1987 1989 ,
Figure 3. Earthquakes between impoundment and March 1992.
i 5
. 1650 l
900- l CUMULATIVE SEISMICITY
-- 8000
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800 --
7000 p 3
j 700 -- c u
c - 6000 -
$ 600 -- 2 en
$ -- 5000 G
'00 --
>5 i tn
~ 4000 400 --
0 300 -- 3000 b 2 [ ' '
2 200 -- MONTHLYSEISMICITY 2000 h
100 -- , l1 1000 0 >
> ' ". ". "-.E IA Le-h 7--.7- 7..
.y 0
1978 1980 1982 1984 1986 1988 1990 Figure 4. Monthly seismicity (bars) and cumulative seismicity (line) near Monticello Reservoir since impoundment.
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o I I 1 16 31 46 61 76 91 Figure 5. Comparison of daily reservoir level, changes in reservoir level, number l
of earthquakes and the log of energy release in ergs per day at l .
Monticello Reservoir. Error bars in the top panel indicate daily fluctuations in reservoir level.
7
a IA-.
6 APPENDIXI
' STATION LOC .TIONS STATION LAT'N LONG*W JSC 31 16.80' 81 15.60' MR01- 34'19.91' 81 17,74' 1
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' e
+
8
i APPENDIX 11 SEISMIC STATION OPERATIONAL STATUS s JANUARY -MARCH 1992 STATION % DOWNTIME JSC 0 MR01 2 MR02 3 MR05 0 MR07 0 MR10 0 4
4 9
APPENDIXIII MONTICELLO RESERVOIR I
i-.
VELOGTY MODEL l
l l
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 4
9 10
APPENDIX IV MONTICELLO EARTHQUAKES HYPO 71 FORMAT Column 1 Date 1 Column 2 Origin time (UTC) h.m.sec.
Column 3 Latitude (N) degrees, min.
Column 4 Longitude OV) 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 = 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'.
Column 13 Quality of the epicentrallocation.
- Statistical interpretation 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.
11
APPENDIX V MONTICELLO RESERVOIR EARTHQUAKES JANUARY- MARCH 1992 DATE ORIGIN LAT H LONG W DEPTH MAG NO GAP DMIN RMS ERH ERZ OM 920225 1337 42.78 34-20.00 81-18.64 1.18 1.02 10 159 2.5 0.08 0.5 1.9 B1 920220 1010 10.46 34-19.79 81-18.74 1.31 0.21 10 153 2.4 0.10 0.4 1.3 B1 920301 8 0 47.48 34-20.07 81-18.68 0.97 0.82 10 159 2.4 0.06 0.3 1.7 B1 k
12
APPENDIX VI
, LIST OF EVENTS WITH (S P)62.5 SEC RECORDED AROUND MONTICELLO RESERVOIR DURING JANUARY-MARCH 1992 DATE STATION P ARR. TIME S-P(SEC) EP.DIST DUR (S) MAG (S P)X8.5 92 01 11 MR07 19 40 37.25
- _ 6 -0.2 92 02 25 MR07 14 42 31.75 0.7 6 8 0 JSC 14 42 32.15 1 92 02 25 MR07 14 46 13.40 0.6 5.1 7 0.1 JSC 14 46 14.00 1.1 92 02 25 MR07 15 00 20.95 0.55 4.7 6 -0.2 JSC 15 00 21.50 0.8 92 02 26 MR07 02 11 18.60 0.5 4.3 5 -0.4 92 02 26 MR07 01 12 36.15 0.55 4.7 5 -0.4 92 02 26 MR07 02 30 00.80
- _ 5 -0.4 92 02 26 MR07 02 33 36.50 0.6 5.1 5 ~0.4 92 02 26 MR07 08 45 32.15 0.65 5.5 5 -0.4 JSC 08 45 33.35 0.85 92 02 26 MR07 13 31 51.80 0.5 4.3 5 -0.4
- (S-P) not clear. The event is very close to the station.
l L
13 l
AppendixVII 9
Maximum and minimum water levels, change in water level, number of earthquakes and energy release (crgs per day) at Monticello Reservoir during January-March,1992. Dates are given in Julian Calender.
DATE WL(min) WL(mar) WL(ava) Change EOS Log E 1 423.2 423.6 423.2 0.4 0 0 2 423.6 425 424.5 1.4 0 0 3 424.1 424.4 424.2 0.3 0 0 4 424.1 _424.2 424 0.1 0 0
S 424 424.1 424 0.1 0 0 6 423.5 425 424.5 1.5 0 0 7 423.4 423.9 423.5 0.5 0 0 8 423.7 424.8 424.4 1.1 0 0 9 423.7 424.9 424.5 1.2 0 0 10 423.9 424.5 424.1 0.6 0 0 11 423.8 424.6 424.4 0.8 1 11.44 12 423.6 423.3 423.3 0.3 0 0 13 423.3 423.9 423.7 0.6 0 0 14 423.9 424.7 424.4 0.8 0 0 15 424.4 425 424.0 0.6 0 0 16 424.5 424.9 424.9 0.4 0 0 17 423.6 424.8 424.2 1.2 0 0 18 424.1 424.7 424.4 0.6 0 0 19 423.9 425 424.7 1.1 0 0 20 423.8 424.9 424.9 1.1 0 0 21 423.7 425 424 1.3 0 0 22 423.8 424.9 424.4 1.1 0 0 23 424.4 424.6 424.5 0.2 0 0 24 424 424.5 424.1 0.5 0 0 25 422.2 424.3 423.3 2.1 0 0 26 422.2 423.9 423.2 1.7 0 0 27 423.8 424.9 424.2 1.1 0 0 28 423.8 424.3 424.1 0.5 0 0 29 424.7 423.9 424.4 -0.8 0 0 30 424.2 423.~5 423.8 -0.7 0 0 31 423.2 423.7 423.5 0.5 0 0 32 423.2 423.9 423.7 0.7 0 0 33 423.3 423 423.1 0.3 0 0 34 423.2 424.3 423.7 1.1 0 0 35 423.3 424.2 423.9 0.9 0 0 36 423.8 424.9 424.3 1.1 0 0 37 423.2 424 423.6 0.8 0 0 38 423.6 424.9 424.4 1.3 0 0 39 423.7 424.5 424.1 0.8 0 0 40 423.7 424.4 424.2 0.7 0 0 41 424 424.8 424.5 0.8 0 0 42 423.7 424 42^$.8 0.3 0 0 43 423.9 424.9 424.7 0 1 0 44 423.7 424.7 424.1 0 1 0 45 423.7 424.9 424.3 1.2 0 0 46 423.2 424.2 423.8 0 1 0 47 423.2 424.4 424 1.2 0 0 48 422.9 424.5 423.9 1.6 0 0 49 423.1 424.5 423.8 1.4 0
- 0 50 423.2 424.3 423.7 1.1 0 0 51 422.4 423.9 423.2 1.5 0 0 52 422.3 423.9 422.9 1.6 0 0 53 422.4 424.2 423.7 1.8 0 0 54 423 424 423 5 1 0 0 55 423 424.1 423.6 1.1 0 0 14
4 0
9 s
56 422.8 423.7 423.3 0.9 4 13.89 57 423 424.1 423.8 1.1 7 12.36 58 423.4 424 423.6 0.6 0 0 59 423.2 423.0 423.5 0.6 0 0 60 423 423.3 423.1 0.3 0 0 61 423 423 423 0 1 13.04 62 423 424.1 423.6 1.1 0 0 63 423.5 _424 423.7 0.5 0 0 64 423.8 ~ 425 424.7 1.2 0 0 65 424.7 424.5 424.6 -0.2 0 0 66 424.5 424.9 424.7 0.4 0 0 67 424.1 424.8 424.5 0.7 0 0 68 424 424.8 424.4 0.8 0 0 69 424 424.P 424.6 0.8 0 0 70 424.1 424.6 424.5 0.5 0 0 71 423.8 424.7 424.2 0.9 0 0 72 423.8 424.9 424.3 1.1 0 0 73 424 425 424.6 1 0 0 74 423.3 424.5 423.8 1.2 0 0 75 423.2 423.5 423.3 0.3 0 0 76 423.1 424.6 4?3.6 1.5 0 0 77 423.3 424.7 424 1.4 0 0 78 424 425 424.5 1 0 0 79 423.5 424.4 424 0.9 0 0 80 423.5 424.2 423.9 0.7 0 0 81 423.7 424.7 423.9 1 0 0 82 423.7 424.1 423.9 0.4 0 0 83 423.9 424.9 424.5 1 0 0 84 423.7 424.7 424.1 1 0 0 85 423.9 424.9 424.4 1 0 0 86 424.3 424 424.1 -0.3 0 0 87 423.5 424 423.9 0.5 0 0 88 423.6 424 423.9 0.4 0 0 89 423.7 424 423.9 0.3 0 0 90 423.8 424.4 424.3 0.6 0 0 91 423.9 424.1 424 0.2 0 0 i
l 15
. .