ML20155E372
| ML20155E372 | |
| Person / Time | |
|---|---|
| Site: | Summer  |
| Issue date: | 03/31/1988 |
| From: | Talwani P SOUTH CAROLINA, UNIV. OF, COLUMBIA, SC |
| To: | |
| Shared Package | |
| ML20155E331 | List: |
| References | |
| 88-1, NUDOCS 8806160076 | |
| Download: ML20155E372 (16) | |
Text
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TECHNICAL REPORT 88-1 SEISMIC ACTIVITY NEAR THE V.C. SUMMER NUCLEAR STATION For the Period January - March 1988 i
by Pradeep Talwani Principal Investigator Department of Geological Sciences University of South Carolina Columbia, S.C. 29208 Contract No. N482355 l
- r=
s s _
l TECHNICAL REPORT 88-1 SEISMIC ACTIVITY NEAR THE V.C.
SUMMER NUCLEAR STATION FOR THE PERIOD l
JANUARY - MARCH 1988 BY PRADEEP TALWANI PRINCIPAL INVESTIGATOP.
STEVE ACREE KEVIN SEVERANCE VINITA ARORA DEPARTMENT OF GEOLOGICAL SCIENCES UNIVERSITY OF SOUTH CAROLINA
- COLUMBIA, S.C.
29208 CONTRACT NO. N482355 I
i t
1
l i
INTRODUCTION Analysis of the seismic activity near the V.C.
Summer Nuclear Station in South Carolina between January 1 and March 31, 1988 is presented in this report.
During this period a total of sixteen events were recorded.
All events were located.
The largest shock was of magnitude 1.4 (February 23 - 1350 UTC).
Fifty percent (8) of the earthquakes were of magnitudes greater than zero.
Five shocks were of B quality and were located at depths of 1.0 to 1.) km.
SEISMIC NETWORK Earthquakes recorded during this period were located using stations of the SCE&G and USC networks.
The configuration of the stations utilized to locate the events in this report is shown in Figure 1 and station coordinates are listed in Appendix I.
DATA ANALYSIS 1
Hypocentral locations of the events were determined using the computer program HYPO 71 (Lee and Lahr, 1972) and the velocity model listed in Appendix II.
The event magnitude (M ) was g
determined from the signal duration at station JSC, using the following relation:
ML = -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 ) energy (E) relation by Gutenberg and g
Richter (1956):
s
2 s.
N J !
MONTICELLO RESERVOIR di 7
1
!'10 3
f
=-
AJSC STUDY AREA
\\.Y O
0 SKM
=
SOUTH A
CAROLINA Figure 1.
Seismic stations utilized to locate earthquakes near Monticello Reservoir during January-March 1988.
3 e
log E = 11.8 + 1.5 M 10 g
OBSERVED SEISMICITY FOR THE PERIOD JANUARY-MARCH 1988 During this period sixteen events were recorded and located (see Appendix III).
This level of activity was similar to that observed during the previous reporting period, and the long-term decline in seismicity is continuing (Figure 2).
The largest event of this quarter (M =1.4) occurred on February 23 at 1350 L
UTC.
Eight shocks (50%) were of magnitudes greater than zero.
The epicenters of earthquakes located during this quarter and during each month are presented in Figure 3 - 6.
The majority of the earthquakes during this period were clustered on l
the western shore of the reservoir.
Five earthquake locations were of quality B or better.
These events were located between depths of 1.0 km and 1.9 km.
CORRELATION OF RESERVOIR WATER LEVEL WITH SEISMICITY Monticello Reservoir is a pumped storage facility.
Any decrease in reservoir level associated with power generation is recovered when water is pumped back into tne reservoir.
There can be normal variations up to approximately five feet per day between the maximum and minimum water level.
We have been monitoring the water level to see if there is any correlation between the daily or seasonal changes in the reservoir level and the local seismicity.
Water level was compared with seismicity In Figure 7.
The top two plots show the median water level and the change in water level each day.
The number of events per day
1700 1600 m:
E aoo s
b 57ao 2
l l
I
@" l!
U-i
^
l3 =
l l
s l
4 l
8-
- l i
h I
soo 5
l 5
jg 200 i
l Ws t
a to e
a i
i 1
s ha!!4 laa ! 1 a JhE! mim!slhas.
_RE _ ! gll}illk R.m __.!!,
st I
i i
i i
i i
1978 1979 1980 1981 1982 1983 1984 1985 1988 1987 1988 l
Figure 2.
Earthquakes per month between reservoir impoundment and March 1988.
5 MONTICELLO EARTHOUAKES JANUARY - MARCH 1988
- 81 '
m 22.0 21.0 20.0 19.0 18.0 17.0 16.0 I
f 1
1 1
1 I
I f
f I
f f
f
_24.0 23.5
_23.0
_22.5
.22.0 e
_21.5 e
_2i.0 x
O
_20.5 s
_20.0 e
_19.5
_19.0 18.5
_18.0
^
_17.5
_17.0
_16.5
_16.0
_15.5 34 '
i i
i i
i i
i i
i i
i i
i i
0 KILOMETERS 5
I f
f f
I f
e 0
0 3 6 O
O A
+ X 0
-1 0
1 2
3 4
0 1
2 3
4 5
6 MAGNITUDE DEPTH (KM)
Figure 3.
Seismic activity at Monticello Reservoir during January-March 1988.
6 MONTICELLO EARTHOUAKES JANUARY 1988 x
31 '
22.0 21.0 20.0 19.0 18.0 17.0 16.0 1
I f
f f
I 1
1 I
t 1
I I
24.0
_23.5
_23.0
_22.5
_22.0
_21.5
_21.0
_20.5.
_20.0
_19.5
_19.0
_18.5
_18.0
_17.5
_17.0
_16.5
_16.0
_15.5 34~
i i
i i
i i
e i
i i
i i
i i
0 KILOMETERS 5
l I
f I
1 1
m a
O 0] 6 O
O A +
X o
- 1 0
1 2
3 4
0 1
2 3
4 5
8 MAGNITUDE DEPTH (KM)
Figure 4.
Seismic activity at Monticello Reservoir during January 1988.
7 MONTICELLO EARTHOUAKES FEBRUARY 1988 81 22.0 21.0 20.0 19 0 18.0 17.0 16.0 i
t i
I t
I f
f f
f I
I f
I
_24.0
_23.5
_23.0
_22.5
_22.0
_21.5
_21.0 x
0
_20.5 0
_20.0
_19.5
_19.0
_18.5
_18.0
_17.5
_i7.0
_16.5
_16.0
_15.5 34 e
i i
i i
i i
i i
i i
e i
i 0
KILOMETERS 5
I f
1 I
1 i
e D D E) @
D 0 6 + X o
-1 0
1 2
3 4
0 1
2 3
4 5
8 MAGNITUDE DEPTH (KM)
\\
Figure 5.
Seismic activity at Monticello Reservoir during February 1988.
8 MONTICELLO EARTHOUAKES MARCH 1988 22.0 21.0 20.0 19.0 18.0 17.0 16.0 I
l I
I I
I l
i I
f I
i 1
a
_24.0
_23.5 23 0-22.5
_22.0 O
_ 21 5 21 0~
_%0 5
_20.0
_19 5
_19.0
_18.5
_18.0
_17.5
_17 0 16.5
_16 0
_15.5 34 i
i i
i i
i i
i i
i i
i i
0 KILOMETERS 5
f I
I f
I I
e 0
0 E] $
0 0 a +
X o al 0
1 2
3 4
0 1
2 3
4 5
6 MAGNITUDE DEPTH (KM)
Figure 6.
Seismic activity at Monticello Reservoir during March 1988.
O h
WATER LEVEL AVERAGE WATER
~
NUMBER OF EVENTS LOG ENERGY CHANGE (FEET)
LEVEL (FEET) e e
e r
- e e
re c
o a
o
=
o a
o o
?
?
i i
i e
s I"
P gy 6 *E E
~ ;:
6.-
g-a,y
=. -
a n8 O O.
- n H m?-A y
D t.r 0_
g
.Y I e o.
C.-
C fa r
. -. =
o.
z.k. ~
~
~
'~
1*
ny o-4V o
o7 a
H IT13 n<
~
~
~
~
NH 2
Za a"
n 99 H
?-A G a e.
.M. a.
F
- n. U Q -
85 S
10 and the log of the energy released per day are shown in the lower two histograms.
There is no apparent correlation between the change in median water level or daily water level fluctuations and seismicity.
CONCLUSIONS The level of activity observed during the first quarter of 1988 was not significantly different from that observed during the fourth quarter of 1987.
The largest event was of magnitude 1.4.
Eight of the sixteen earthquakes were of magnitudes greater than 0.0.
The five quality B earthquake locations range in depth from 1.0 to 1.9 km.
REFERENCES Gutenberg, B.
and Richter, C.F. (1956).
Magnitude and energy of earthquakes, Ann. Geof.
9, p.
1-15.
l
- 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.
l
11 APPENDIX I STATION LOCATIONS NO.
STN.
LAT.*N LONG.*W 1
J3C 34* 16.80' 81* 15.60' 2
001 34* 19.918 81* 17.74' 3
002 34* 11.58' 81* 13.81' 4
007 34* 22.23' 81* 19.50' 5
008 34* 24.53' 81* 24.55' 6
010 34* 20.18' 81* 20.25' 0
.,__.-.,._,,_..__,,____.,,,,..,__,..__._.._,._.,.._,,...,y._
,sk mw a
s e,
,L+4=-
4 La e
a 4A 1
6 --
l 12 APPENDIX II MONTICELLO PESERVOIR VELOCITY MODEL Velocity-Depth to top l
km/sec km 1.00 0.00 i
5.40 0.03 5.90 0.18 6.10 0.46 6.30 0.82 8.10 30.00 l
9
,y W m wr t - + *y e at we y*b me e T-w s F F M -*" W -W*
13 APPENDIX III MONTICELLO EARTHQUAKES JANUARY-MARCH 1988 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 squarg/NO, error of time residuals in sec.
RMS =
R where R is the time residual for t e ith station Column 11 Standard error of the epicenter in km*.
Column 12 Standard error of the focal depth in km*.
- Statistical interpretation of standard errors involves assump-tions which may not be met in earthquake locations.
Therefore standard errors may not represent actual error limits.
If ERH or ERZ is blank, this means that it cannot be computed, because of insufficient data.
\\
14 NONTICBLLO EARTHQUAKES JANUARY-MARCH 1988 DATE ORIGIN LAT N LONG W DEPTH MAG NO GAP DMIN RMS ERH ERZ QM 880110 216 17.46 34-17.64 81-20.29 2.91 0.37 9 222 4.7 0.08 0.7 1.6 C1 880110 353 38.12 34-t0.45 81-19.02 0.41
-0.86 4 232 3.3 0.05 C1 880130 7 0 19.04 34-24.97 81-21.10 7.80 0.37 5 339 5.6 0.09 3.9 1.9 D1 880212 1235 58.45 34-20.28 81-20.35 1.00 0.87 7 232 0.2 0.08 1.2 1.0 C1 880217 0 7 36.29 34-20.77 81-19,86 1.28 0.78 8 163 1.2 0.01 0.1 0.2 B1 i
880217 018 44.20 34-21.00 81-19.60 1.95
-1.22 4 150 1.8 0.02 C1 880223 1350 16.22 34-20.52 81-20.39 4.60
-0.60 5 222 0.7 0.02 0.4 0.5 C1 l
880223 1350 30.05 34-20.54 81-19.30 1.00 1.39 6 121 1.6 0.08 0.9 3.0 B1 880223 1354 7.72 34-20.65 81-19.80 3.92
-0.86 4 151 1.1 0.00 C1 880223 14 6 24.00 34-20.62 81-19.73 1.79
-0.60 6 143 1.1 0.05 0.5 1.0 B1 880223 1423 30.22 34-20.28 81-19.65 1.63 0.21 6 123 0.9 0.08 0.7 1.2 B1 5
880302 2146 43.04 34-21.52 81-19.60 1.89 0.01 8 165 1.3 0.09 0.8 1.0 B1 880308 6 5 41.96 34-21.90 81-18.73 2.67 0.29 6 216 1.3 0.05 0.7 0.8 C1 880310 659 43.93 34-20.68 81-19.86 5.13
-0.40 5 158 1.1 0.00 0.1 0.1 C1 880315 631 1.77 34-20.28 81-20.35 2.78
-0.86 5 180 0.2 0.09 2.2 1.1 C1 880324 1251 37.15 34-19.81 81-18.91 1.00
-0.60 6 204 1.8 0.03 0.4 1.0 C1