ML20042E196
| ML20042E196 | |
| Person / Time | |
|---|---|
| Site: | Summer  |
| Issue date: | 12/31/1989 |
| From: | Talwani P SOUTH CAROLINA, UNIV. OF, COLUMBIA, SC |
| To: | |
| Shared Package | |
| ML20042E194 | List: |
| References | |
| NUDOCS 9004200380 | |
| Download: ML20042E196 (20) | |
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,' : TECHNICAL REPORT 89 '
s L* SEISMIC ACTIVITY NEAR THE V.C. SUMMER NUCLEAR STATION For the Period 4 October - December 1989 l. by. Pradeep Taiwani. Principal Investigator Department of Geological-Sciences i
- >- University of South Carolina r Columbia, SC 29208 a i
- .
- Contract No. N482355 '
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. TECHNICAL REPORT =89-4' r!
# 3 SEISMIC: ACTIVITY NEAR j THE V.C. SUMMER NUCLEAR STATION- 4
~t FOR1THE PERIOD 1 l
OCTOBER DECEMBER' 1989 l l' BY t-t C . .PRADEEP TALWANI I'
' PRINCIPAL' INVESTIGATOR =
i l KUSALA-RAJENDRAN-t i DEPARTMENT 10F. GEOLOGICAL' SCIENCES r UNIVERSITY OF SOUTH. CAROLINA
- COLUMBIA,.SC' 29208-i.
r s CONTRACT NO. N482355
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, INTRODUCTION- -
Analysis of the seismic = activity near the V.C. Summer Nuclear
,e Station-in South Carolina between October 1 and December 31, l 1989, is-presented in this report.- During this period, sixteen events of magnitude (1.2 occurred in the vicinity of'the Monti-cello' Reservoir. However,'only six of these events could1be. q Iocated due to lack of sufficient station coverage.- One event of ,
-magnitude.l.2 occurred outside-and to the North of-the Monticello network. Stations:001 and 002 were. inoperable during most of this period, thus limiting the number of records available'.
l SEISMIC NETWORK L . Earthquakes were recorded during this period at. stations.of the Monticello Reservoir and. South Carolina networks. The. con-l figuration 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 Hypocentral'1ocations of the events have been determined using the computer program HYPO 71 (Lee and Lahr, 1972) whose t . ! format is listed in Appendix III. The velocity model used to l . . J locate the events is listed in Appendix II.- The-event magnitude l-(Mg ) was determined from the signal duration at. station JSC, j using the following relation: - Mg = -1.83 + 2.04 Log D,
+cra D is- the signal duration (seconds) .-
r - estimate of daily energy release was_ determined using a. saus11fied magnitude (ML ) energy (E) relation by Gutenberg and.
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1 i.' Figure 1. Location map of Monticello Reservoir area showing seismic stations l used in locating activity during this period. I
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a Richter (1956): log 10 E = 11.8 + 1.5 M g.
*?
OBSERVED SEISMICITY'FOR THE PERIOD OCTOBER - DECEMBER 1989
.' Most of the events during this period were identified on the .
basis of signal duration and rangelof S-P as-recorded at JSC. Those with a S-P value (2.5 s were considered:as possible Monti-cello-Reservoir events. Only six events could be located reliably.- These are listed in Appendix IV and plotted in Figure
- 2. The other (nonlocated) eventsfare listed in Appendix 17.
Although they could not be located, their' contribution to energy
. release was-included in Figure 4.- One-event on December 7 (1717 UTC), uhjch was located to the North of the reservoir (Figure 2) with an S-P of 2.5 s, is listed in Appendix V but- is not: included l '
in the energy plot, q Several events recorded during this period were identified as ; quarry blastst and are not. included in this report. Figure-2 also I shows the location of one event outside the Monticello Reservoir which occurred on December 8 (1737 UTC). This is' included since there was an event in the same location during.-the last quarter also (September 20, 1708 UTC), and these events may be related to seismicity in Monticello Reservoir. Seismic data for this period indicates a minor increase in the number of events compared to the previous reporting period, but the long-term decline in seismicity is continuing (Figure 3). 4 O Of the six located events reported in the immediate reservoir ! area, two were of magnitude ML = 1.2, which occurred on. October . 17 (15:15 UTC) and December 23 (2019 UTC), respectively. 3
c - - - MONTICELLO-EARTHOUAKES October - Decemb'er, 1989-
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'The operstions1Lstatus of the seismic network is shown in l Appendix VI. The records from station 09A were used in ident',
E' fying and locating the events, replacing those from stations 001 l and 002 which were down; CORRELATION =OF RESERVOIR WATER LEVEL WITH SEISMICITY Monticello Reservoir is L pumped storage f acility. - Any.de-crease in reservoir level associated with power generation-As-recovered when water is pumped backiinto the reserroir. -There can be normal variations up.to approximately five _aet per day , between the maximum-and minimum water level. The water level has been monitored to see if there is any correlation betweenhe daily or seasonal changes in the reservoir leve1~and the local seismicity. Water level is' compared with' seismicity in Figure 4. The top plot shows the median water-level. The number of events per day and the-log of the energy released per day are.shown-in the lower two histograms. There is no systematic correlation i between the daily water level fluctuations and seismicity during ! this quarter. However, the three events'on December 8 (two'of-which were located) and the two events on December 23 fo11 owed l noticeable changes in water level. CONCLUSIONS The level of activity during the fourth quarter of 1989 was low, but compared to the previous quarter more events were ob . l
~ ' served. Two events of magnitude 1.2-in the immedia te reservoir .
1 area were located. Ten other events, which'are suspected to be e from the Mc. ':ello Reservoir area are also reported but these
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could not be located due to lack of sufiacient data. 7
4-
SUMMARY
OF 1989 SEISMICITY-Seismic activity during 1989-(60 events):-was lower than that of 1988 (87 events). The number of events per day-recorded during 1989 is shown in Figure 5.- Of-the 60 events, 50 (83%) were' located. A gteater number of events. occurred during the first ha: 5 of the_yere than theLsecond (Appendix VII). Epicen a tral locations of evento during the-last quarter are not well: constrained due to inoperability of stations 001 and 002. A e
~
majority of the 1989 events were located beneath the -reservoir: (Figure 6). Fourteen (28%)'cf the located events were of'B quality and one i event was of A quality. The majority of the B quality events q were located at depths between 1.5 and 2.0 km ; Figure 7). The A- , i quality event was very shallow (0.17 km). The largest event of. ! the year was of magnitude 1.9_(April 2, 1645 UTC). .Nine of the j i located events (16%) were of magnitudes 1.0 or. greater. -j In summary, seismicity at'Monticello Reservoir continued to decline during 1989. With the exception of a swarm on March 29,
'I '
the activity was low throughout the year. l REFERENCES l 1 Gutenberg, B. and Richter, C.F. (1956). Magnitude and energy of ~ earthquakes, Ann. Geot. 9, 1-15. : Lee, W.H.K. and Lahr, J.C, (1972). A computer prwyram for deter-mining hypocenter, magnitude and first motion pattern of ; local earthquakes, ReviLions of HYP071, U.S. Geclogical ! Survey Open-File Report, 100 p. ii 8 1
,4 APPENDIX I i-STATION LOCATIONS-No. STN. LAT.*N LONG.*W 1- JSC' 34* 16.80' 81* 15.60' 2- 001 348 19.91'- 81* 17.74' 3 002 34*'11.68' 81*'13.81'-
4 005 34' 16.05' - 81* 20.05' 5 007 348 22.23' 81* 19.508-6 010 240 20.18' .81* 20.25' j 7 09A' 34* _17.24' 81* 19.75'- -1 i i
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-APPENDIX.II MONTICELLO RESERVOIR , ti h
9 VELOCITY MODEL-
-Velocity Depth.to top ~
km/sec km 1.00 0.00 5.40 0.03
'S.90 .o.13 6.10 0.46 6.30 0.82 .
l 8.10 30.00 i i i N i 10 - p.
- . _ . . . i.....,...i.
_~ __ . t = i APPENDIX III
-b MONTICELLO EARTHQUALES 1 OCTOBER - 31< DECEMBER 1989 NYP071 FORMAT ,
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~ Column 1. .Date i Column 2 Origin 1 time '- (UTC ) h.m.sec. t Column 3- : Latitude-(N) degrees, min.
Column 4 Longitude'(W)L: degrees, min.-
- Column S. Depth (km)
Column 6 Local duration magnitude < q i: Column 7 No. ofnstation readings used to locate event. l P-and1S arrivals from same stations are regarded.as 2. readings
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[ Column 8 Largest azimuthal. separation in degrees j between stations . Column 9 . Epicentral distancerin ka to. nearest' station Column 10 Root mean square error of time residuals in j sec. RMS = R1 2/NO, where A, : is - the time ; l residual for:the ith-station'
- f. Column 11 Standard error of the^ epicenter in-km*
Column 12 Standard error of:the-focal depth in km* l [ i' . 1- - Statistical interpretation.of-standard errors involves.assump- 1 ! tions which may not'be met in earthquake locations. Therefore,
- standard' errors may not represent actual error limits. i k -i I
- If ERH or ERZ is blank, this means.that it cannot be computed j because of insufficient data. l lr-
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APPENDIX'IV HONTICELLO EARTHQUAKES: OCTOBER-DECEMBER 1989' i DATE. ORIGIN- LAT K ..LONG W : DEPTH 2 MAG 'NO GAP DMIN RMS ERH' -ERZ QN 891017 1515 19.26 34-20.13' 81-17.29 1. 00.- 1.18 4 277- 0.8 0.02- - C1 , 891208 1142 -5.96' 34-19.83: 81-17.54- ~0 . 88 1.02> 3 297- 5.9 0.04- C1 i
' 891208. 1737.58.09 34-16.90 81-15.70 1.00 1.18 4' 225 0.2 1~.14 : D1 822 8.91 34-20.86 891215 81-19.42 0.85. '0.81 4' 318 6.7- 4.10 C1 891223 2019-12.70 34-16.22- 81-18.38-m
-4.34 0.57 .4 236- :2.8 0.05 0.5' . 1.1 C1 ;
891223.-2019 41.13. 34-17.34 81-18.00 1.97 1.18 3 199 2.7 0.00 C1 + .- . . - -- . - - - . - - - - . _ - _ l 12
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. APPENDIX ~V .
LIST OF- EVENTS WITH-(S-P (2.5 sec)- 1: OCTOBER - 31 DECEMBER,1989-DATE- STATION P-ARRIVAL TIME S-P- EP. DIST: MAG H MIN SEC . sec (s-p)8.5 km 4 89 10 20: JSC Ol' 33 -38.60 0.65 5.5- 0.21 89 10'20 JSC 01 47 56.22 0.28 2.3 .0.44 -l 89 11 04~ JSC 10 48 42.50- - .- -0.4 89 11 07 JSC- 03 52 36.70 1.00 8.5 0.82 89 11 07 JSC- 11- 30 37.50- - -
-0.4 89 11-07 JSC 14 59 55.70' O.90 7.6 -
-0.4-89 11 07 JSC 19 47 47.05 0.45 3.8 0.82 89 11 07 JSC 20 15 17.60. 0.90 7.6 1.02:
89 12 07, JSC 17 17 16.55 2.50 21.0 1.18 i 89 12 08 JSC 11 36 07.55 1.00 -8,5 0.57 89 12.15 JSC 20 39 04.70 1.70 4.2 0.57 This event was located to the North of-the. reservoir and the ; location is not reliable. This la not included in the energy plot. J i
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. *,. ' e APPENDIXLV*i
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'- SEISMIC STATION OPERATIONAL STATUS l ll OCTOBER - 311 DECEMBER 19891 STATION ,
PERCENT DOWNTIME JSC' 0% 001 80%-- 002- 80% 09A-50%
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APPENDIX VII- ) MONTICELLO EARTHQUAKES: JANUARY-DECEMBER-1989 i
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!!8:11 ' lit it:t! :itilt ti:1?:It 1:8 :8:31 11198 :8tt:8:8: i:s i:8 1 -
r it8n i 13.1 *!:11 :lt:l! 11:11:t! i:a : -?: n ! !!! 8 5 8:81 : ' 81 4 4 188!i!ili?It:if 1:18:81.11:11:11 i:t a:t'Rf 128 ati 8:88 L1:?7- 1:181 - 188818 88 li:St 2:18:8? 11:18:9 a:t 8:li ! fit %:t 8:?! - **81 ' It8lli li.t: 8:11 1:18:!! 11:19:12. 1:8 -a:it I !!! !:1 8:89-81 i i 18?t*if ilti 18:12 1:18:f! 11:19: 1 1:8 liti ! I?f 8:! 8:8! 81 1 e !!ilat1119.1:88-1:18:88 li:ll:Po i:8 1:?l ! Ili '8:1 i:ii l' 1 i
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' i MONTICELLO EARTHOUAKES January'- December.. 1989' ,
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-( TOTAL NUMBER OF EVENTS.= 15 ) I I
Figure 7.-Depth distribution of A and B quality events at Monticello Reservoir during 1989, 1
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