ML20065F304

Technical Rept 93-4, Seismic Activity Near Vsns for Period Oct-Dec 1993

ML20065F304
Person / Time
Site:	Summer
Issue date:	12/31/1993
From:	Talwani P SOUTH CAROLINA, UNIV. OF, COLUMBIA, SC
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ML20065F296	List: ML20065F298 ML20065F304 RC-94-0096, Forwards Technical Rept 93-3, Seismic Activity Near Vsns for Period Jul-Sept 1993 & Technical Rept 93-4, Seismic Activity Near Vsns for Period Oct-Dec 1993
References
NUDOCS 9404110306
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i

~ l TECHNICAL REPORT 93-4 I

i l

SEISMIC ACTIVITY NEAR THE I

V.C. SUMMER NUCLEAR STATION FOR THE PERIOD OCTOBER-DECEMBER,1993 l BY PRADEEP TALWANI Principal Investigator DEPARTMENT OF GEOLOGICAL SCIENCES UNIVERSITY OF SOUTH CAROLINA COLUMBIA, SOUTH CAROLINA 29208 i

CONTRACT NO. N622702 9404110306 9404o4

{DR ADOCK 05000395 PDR

1 TECHNICAL REPORT 93-4 l'

SEISMIC ACTIVITY NEAR THE i

V.C. SUMMER NUCLEAR STATION

FOR THE PERIOD OCTOBER-DECEMBER,1993 BY i

PRADEEP TALWANI Principal Investigator i

and Robert Trenkamp 4

l-DEPARTMENT OF GEOLOGICAL SCIENCES UNIVERSITY OF SOUTH CAROLINA 4

COLUMBIA, SOUTH CAROLINA 29208 e

i CONTRACT NO. N622702 1

1 INTRODUCTION Analysis of the seismic activity near the V.C. Summer Nuclear Station in South Carolina between October 1 and December 31,1993 is presented in this report. During this period, four events were recorded and located in the vicinity of the Monticello Reservoir. All were of relatively low magnitude.

A compilation of the locatable seismic activity and station performance for the year  !

1993 is also included in Appendix VII pages 15-23.

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 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 relation: was determined from the signal duration at JSC using the following M L= -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):

Logio E = 11.8 + 1.5 ML OBSERVED SEISMICITY DURING OCTOBER-DECEMBER,1993 Four events were recorded and located during the fourth quarter of 1993. All events occurred to the southeast of the Monticello Reservoir and only one event was located within the confines of the reservoir proper (Figure 2). All locations were good to fair (B-C; Appendix V).

The earthquake occurrences were spaced throughout the quarter and ranged in magnitude from M =t -0.68 to Mt = 0.28. The largest event occurred on October 1,1993 at 16:28 UTC a.'d was the one event located within the confines of the reservoir (Figure 2).

The finai turee events were spaced throughout the rest of the quarter and were located in a fairly tight cluster to the southeast (Figure 2). 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. l 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 j

' 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.

i CONCLUSIONS Seismicity during the fourth quarter of 1993 was lower than that of the third quarter and occurred in the southeastern section of the reservoir. There was no unusual seismic activity and the activity' was scattered temporally. No systematic correlation was observed between the reservoir level fluctuations and the seismicity.

} REFERENCES i

l Gutenberg, B. and Richter, C.F. (1956). Magnitude and energy of earthquakes, Ann.

Geof. 9,1-15.

4 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 yp.

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J Monticello Reservoir Seismic Network

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A Single component '

$ 3 component l Figure 1 Location of Monticello Reservoir seismic stations.

3

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Monticello Reservoir Seismicity i

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Events located near Monticello Reservoir during the period October - December, 1993 (stars) 4 1

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l  :  :  : l l l l l l  : l  : 0 1977 1979 1981 1983 1985 1987 1989 1991 1993 Figure 4.

Cumulative seismicity near Monticello Reservoir since impoundment.

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Comparison of daily lake level, changes in lake level, number of earthqu and the log of energy release in ergs per day at Monticello Reservoir. Error bars in th'e top panel indicate daily fluctuations in water level.

7

I i- 1 1

]

APPENDIX I-STATION LOCATIONSi 4

4 STATION- LAT N' LONG W.

. JSd 34 16.80'~ -81 15.60'-- -

MR01 34 19.91' '81 17.74

MR02 34 11.58' ' 81 13.81' MR05 34 16.05' .'81 20.05' d

MR07 34 22.23' 81 19.50'.

MR10 34 20.18' 81 20.25' .

4

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APPENDIX -II )'

- SEISMIC STATION OPERATIONAL STATUS ,

OCTOBER 1 - DECEMBER 31,1993 \

t STATION PERCENT DOWNTIME MR01 17.4 MR02 20.6 MR05 17.4 MR07 17.4 MR10 17.4 JSC 6.5 '

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)

9 '

APPENDIX III MONTICELLO RESERVOIR VELOCITY MODEL Velocity Depth to top 1 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 10

U i

APPENDIX IV MONTICELLO EARTHQUAKES HYPO 71 FORMAT

.l Column 1 Datd 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 = 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

i i

l APPENDIX V MONTICELLO RESERVOIR EARTHQUAKES OCTOBER- DECEMBER,1993 DATE ORIGIN LAT N LONG W DEPTH MAG NO GAP DMIN RMS ERH ERZ QM 931001 1628 49.43 34-18.81 81-17.84 2.28 0.28 8 133 2.0 0.04 0.3 0. 6 B1-931021 829 38.85 34-17.81 81-16.72 2.37 0.03 10 159 2.5 0.15 0.9 1.9 C1 931129 1729 20.70 34-18.35 81-16.21 0.63 0.15 12 197 3.0 0.03 0.2 0.3 C1 931211 2248 46.90 34-18.31 81-16.35 0.77 -0.68 8 191 3.0 0.03 0.2 0.3 C1 12

1 APPENDIX VI l Maximum and minimum water levels, change in water level, number of earthquakes and log of energy release per day at Monticello Reservoir during October 1 - December 31,1993. Dates are given in Julian Calendar.

J.DATE WL(max) WL(min) WL(avg) WL(ch) # of eqs: Energy 274 423.9 423.2 423.7 0.1 1 12.22 275 424.4 423.4 424.1 0.4 0 0 276 424.1 423.4 423.8 -0.3 0 0 277 424.8 422.3 423.8 0 0 0 278 424.9 422.5 423.9 0.1 0 0 279 424.5 422.9 424 0.1 0 0 280 424.3 422.9 423.6 -0.4 0- 0 281 424 422.9 423.6 0 -0 0 282 423.9 423.1 423.6 0 0 0 283 423.5 422.8 423.3 -0.3 0 0 284 424.2 422.9 423.9 0.6 0 0 285 424 423.7 423.9 0 0 0 286 423.8 423.5 423.7 0.2 0 0 287 423.7 423.2 423.5 -0.2 -0 0 288 423.5 422.9 423.2 0.3 0 0 289 424.7 422.9 424.1 0.9 0 'O 290 424.3 424.2 424.3 0.2 0 0 291 424.5 422.4 423.8 -0.5 0 0 292 424.7 421.8 423.4 0.4 0 .0 293 424.5 422 423.5 0.1 0 0 294 424.8 423 424.1 0.6 1 11.85 295 424.3 423.1 424.1 0 0 0 296 424.4 422.2 423.5 -0.6 0 0 297 424 422.3 423.3 0.2 0 0  !

298 423.6 422.6 423.4 0.1 0 0 299 424.2 423 423.6 0.2 0 0 300 424 423 423.7 0.1 0 0 301 424.2 423.2 423.7 0 0 0 302 424.6 423.2 424.2 0.5 0 0 303 424.6 422.6 423.6 -0.6 0 0 304 424.7 422.8 424.1 0.5 0 0 305 424.5 421.8 423.3 -0.8 0 0

306 424.3 422.2 423.5 0.2 0 0 307 424.7 423.4 424 0.5 0 0 308 424.7 423.7 424.3' O.3 0 0 309 424.8 424.1 424.6 0.3 0 0 310 424.5 424.5 424.5 -0.1 0 0 311 424.9 424.6 424.8 0.3 0 l 0 '

312 425 422.9 424.1 -0.7 0 0 313 425 423.3 424.3 0.2 0 0-314 424.9 423.8 424.6 0.3 0 0 315 424.9 423.9 424.3 -0.3 0 0 13

APPENDIX VI (c:ntinu::d)

J.DATE WL(max) WL(min) WL(avg) WL (ch) # of eqs Energy 316 424.3 423.5 423.8 -0.5 0 0 317 423.5 423.1 423.3 -0.5 0 0 318 423,7 423.1 423.5 0.2 0 0 319 424.6 422 423.8 0.3 0 0 320 424.8 422.6 424.1 0.3 0 0 321 424.9 423.1 424.2 0.1 0 0 322 424.8 423.3 424.2 0 0 0 323 423.9 423.4 423.9 -0.3 0 0 324 423.4 423.1 423.2 -0.7 0 0 325 423.6 423.1 423.1 -0.1 0 0 326 424.9 423.6 424.3 1.2 0 0 327 423.6 423.6 423.6 0.7 0 0 328 423.6 423.4 423.5 0.1 0 0 329 423.6 423.4 423.5 0 0 0 330 424.2 423 423.7 0.2 0 0 331 423.9 423 423.6 -0.1 0 0 332 424.1 423.3 423.9 0.3 0 0 333 424.7 423 423.8 -0.1 1 12.03 334 424.9 423.2 423.9 0.1 0 0 335 424.9 423.5 424.1 0.2 0 0 336 424.7 423.5 424.1 0 0 0 337 424.6 423.6 424.4 0.3 0 0 338 424,9 424.2 424.5 0.1 0 0 339 424.3 424 424.2 -0.3 0 0 340 424.3 423.5 424 -0.2 0 0 341 424.8 423.2 423.9 -0.1 0 0 342 424.8 423 423.8 -0.1 0 0 343 424.5 422.4 423.2 -0.6 0 0 344 424.7 422.8 423.9 0.7 0 0 345 424.9 423.7 424.4 0.5 1 10.78 346 424.5 423.7 424 -0.4 0 0 347 424.8 423 423.7 -0.3 0 0 348 425 423.6 424.7 0 1 0 349 425 423.8 424.3 -0.4 0 0 350 425 424 424.7 0.4 0 0 351 424.8 424.8 424.8 0.1 0 0 352 424.8 423.8 424.4 -0.4 0 0 353 424 423.8 423.8 -0.6 0 0 354 424.9 424 424.6 0.8 0 0 355 424.8 424.3 424.7 0.1 0 0 356 424.9 423.3 424.1 -0.6 0 0  !

357 425 423.6 424.5 0.4 0 0 358 425 424.6 424.9 0.4 0 0  !

359 424.9 424,9 424,9 0 0 0 360 424.9 424.8 424.9 0 0 0  !

361 424.8 424.5 424.6 -0.3 0 0 362 424.5 424.4 424.5 -0.1 0 0 363 424.4 421.5 423.1 -1.4 0 0 364 424.7 422 423.5 0.4 0 0 365 424.5 422.5 423.6 0.1 0 0 14 m

a l

APPENDIX VII 1

Monticello Network and Seismicity During 1993 l

STATION OPERATION STATUS i The operational status of the Monticello Network During 1993 is presented in Figures 7 and 8. The gbnerally high downtime for the Monticello Network during the fourth quarter (Figure 8)is due to loss of power at Parr Tower which made the data relay for the network inoperative, accounting for 17.4% of the fourth quarter downtime at each of the MR Stations.

SEISMICITY During 1993 twenty-six events were recorded (Appendix VIII and IX) around the Monticello Reservoir of which twenty-two werelocated. Of the twenty-two located events (appendix VIII) two were blasts at Blair Quarry and have not been plotted in Figure 6. The events were scattered throughout the area of the reservoir but generally can be separated into two groupings, one in the northwest and the other in the southeast (Figure 6). Every month but August had locatable events (Figure 9) with duration magnitudes ranging from Mt = -0.68 to Mt = 1.02 (Figure 6 and Appendix VIII) and occurring at depths from 0.15 to 3.87 km (Figure 11). Eighteen of the twenty located events had magnitudes less than Mt= 1.0 (Figure 10) and most were of good to fair quality (B or C) with only two of poor quality (D) (Appendix VIII).

Seismicity around the Monticello Reservoir in 1993 continued at the relatively low level that has been observed since 1987. Compared to the 1992 seismicity (Figure 12 and Appendix X) more activity was found to the south and southeast and north northwest with no earthquakes located in the center of the reservoir (Figure 6). The greater percentage of good quality locations can be attributed to improved operation of the network and increased efforts to incorporate digital recording techniques.

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Monticello Reservoir Seismicity 1

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Events located near Monticello Reservoir during the year 1993 (stars) )

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Operational status by quarter of Monticello Reservoir seismic sub-network stations dunng 1993. Quarters and stations designated.

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0- 1 1 1 i i i -l .i JAN EB MAR APR MAY JUNE JULY AUG SEP CCT NOV DED Figure 9.

Monthly 1993.

distribution of located earthquakes at Monticello Reservoir during 19

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Magnitude ranges of located earthquakes at Monticello Reservoir during 1993.

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DEPTH TO EARTHQUAKE FOCUS (km)

Figure 11.

Depth distribution of located earthquakes at Monticello Reservoir during i 1993.

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Monticello Reservoir Seismicity o

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Events located near Monticello Reservoir during the year 1992 (stars)

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4 i-i APPENDIX VIII i  !

l b MONTICELLO RESERVOIR EARTHQUAKES i

JANUARY - DECEMBER,1993 i l 1  :

4, ~

j H DATE ORIGIN LAT N LONG W DEPTH MAG NO GAP DMIN RMS ERH ERZ QM l

930111 2227 43.49 34-16.90 81-19.03 3.64 0.82 7 120 2.3 0.04 0.3 0.5 B1 i 930112 043 25.39 34-1).52 81-18.93 0.24 -0.40.12 126 3.2 0.06. 0.3 0.9 B1-930211 1736 46.55 34-22.33 81-19.60 1.94 -0.11 4 307 0.2 0.04 C1 930219 2051 47.72 34-22.33 81-20.95 0.82 1.02 -6 282 2.2 0.08 9.8 8.1 D1 930219 2103 39.42 34-25.06 81-22.71 .3.44 0.82 8 339 7.2 0.03 .0.6 0.6 C1

• 930318 1753 15.06 34-25.25 81-22.72 6.55 0.57 8 341 7.4 0.08 1.6 0;8 C1

• 930322 1855 9.95 34-17.90 81-16.00 0.42 1.02 10 199 2.1 0.08 0.5 .0.8 C1 930428 55G 29.53 34-23.09 81-19.60 1.00 0.01- 8 322 1 6 0.16 E2 . 6

. 1.8 D1 930430 1615 12.49 34-22.09 81-20.72 0.26 0.21 4 274 1.9 0.01 -C1 930524 1622 57.02 34-22.87 81-21.89: 0.20- 0.82 5 300 3.9 0.02' 3.0 1.8 D1 930618 355 10.29 34-20.98 81-19.77 0.66 0.01 7 164 1.6 0.10 1.0 1.9 B1 930714 2006 13.27 34-20.01 81-17.71 2.31 0.16 10 185 0.2 0.05- 0.3 0.3 C1 930906 1122 6.58 34-20.24 81-21.51 0.47- 0.00 12 236 1.9 0.10 0.7- 2.0 C1 930906 1246 37.07,34-20.50 81-19.85 0.05 0.00 7 144 0.8 0.07 0.4 0.9 B1 930906 1542 35.05 34-20.52 81-20.20 0.12 0.00 8 192 0.6 0.03. 0.2 .0.3 C1 930906 1659 37.11 34-20.49 81-20.43 0.48 0.00 8 229 0.6 0.05 0.5 0.5 C1 930906 1717 4.29 34-20,41- 81-20.29 0.04 0.00 6 291 0.4 0.02 0.4 0.4 C1 930911 345 12.04 34-17.38 81-18.49 3.87 -0.27 10 121 3.4.0.25 1.2 2.5 B1 l 931001 1628 49.43 34-18.81 81-17.84 2.28 0.28 8 133 2.0 0,04 0.3 0. 6 B1' 931021 829 38.85 34-17.81 81-16.72 2.37 -0.03 10 159 2.5 0.15 0.9 1.9 C1 931129 1729 20,70 34-18.35 81-16.21 0.63 0.15 12 197 3.0 0.03 0.2 0.3 C1 931211 2248 46.90 34-18.31 81-16.35 0.77 -0.68 8 191 3.0 0.03 0.2 0.3 C1

• Blair quarry blasts which are not plotted on figure 6 -

0 1

23

l APPENDIX IX J

List of Unlocatable Events With (S-P) s 2.5 Seconds Recorded Around Monticello Reservoir During 1993 i

j No DATE STATION P-Arrival S-P .Ep. Distance (km) DUR MAG

HR MIN SEC SEC (S-P) x 8.5 SEC 1

1 93 01 04 JSC 06:46: 59.0 1.5 12.8 J

2 93.01 11 JSC 23:47: 53.5 12 0.37 3 93 02 05 JSC 0.6 5.1- 5 -0.4 i 10:89: 06.0 0.8 6.8 4 -0.6 4 93 03 22 JSC 21:46: 52.0 0.4 3.4 5 -0.4 5

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24 i

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APPENDIX X

• MONTICELLO RESERVOIR EARTHQUAKES JANUARY - DECEMBER,1992 DATE ORIGIN LAT N LONG W DEPTH MAG NO GAP DMIN RMS ERH ERZ QM 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 920226 1010 10.46 34-19.79 81-18.74 1.31 0.21 10 153 2.4 0.10 0.4 1.3 B1 920315 8 0 47.48 34-20.07 81-18.68 0.97 0.82 19 159 2.4 0.06 0.3 1.7 B1 920402 1714 29.62 34-22.33 81-20.66 1.00 1.02 7 281 1.8 0.15 2.9 4.5 D1 920429 1810 2.98 34-23.60 81-17.18 4.90 0.82 7 292 4.4 0.15 3.6 2.7.D1 920521 1431 33.09 34-20.01 81-18.79 0.42 0.21 7 111 1.6 0.08 0.8 2.1 B1 920529 1654 44.12 34-24.09 81-22.80 2.79 1.02 8 333 6.1 0.07 1.2 1.6 C1 920825 1704 57.66 34-24.50 81-24.40 0.69 1.02 7 333 8.6 0.23 5.4 D1

• 920908 1755 43.74 34-21.98 81-16.80 2.00 0.82 6 253 4.2 0.08 1.2 3.6 D1 921005 1959 1.06 34-24.89 81-23.27 1,32 1.18 6 339 6.5 0.01 0.2 1.0 C1 921025 1142 19.73 34-19.64 81-19.23 0.74 -0.11 6 170 1.9 0.08 7.6 11.8 D1 921029 542 54.20 34-19.64 81-19.08 0.42 1.15 8 147 2.0 0.12 1.2 2.6 C1 921107 321 40.11 34-22.33 81-20.11 2.46 1.12 8 278 1.0 0.09 1.0 0.7 C1 921209 2148 49.10 34-19.98 81-20.35 1.50 0.44 8 230 0.4 0.10 1.2 0.8 C1

• Blair quarry blast which is not plotted on figure 12 a