ML20083L651

Seismic Activity Near VC Summer Nuclear Station for Period Oct-Dec 1994

ML20083L651
Person / Time
Site:	Summer
Issue date:	12/31/1994
From:	Cobb J, Talwani P SOUTH CAROLINA, UNIV. OF, COLUMBIA, SC
To:
Shared Package
ML20083L649	List: ML20083L651 RC-95-0134, Forwards Technical Rept 94-4, Seismic Activity Near VC Summer Nuclear Station for Period Oct-Dec 1994
References
94-4, NUDOCS 9505180550
Download: ML20083L651 (26)

Text

c:

y. . :,

i .r . ,

j

..g -. ,

'" ' TECHNICAL REPORT 94-4 4

SEISMIC ACTIVITY NEAR THE V.C. SUMMER NUCLEAR STATION ,

FOR THE PERIOD OCTOBER-DECEMBER,1994 a ,

• BY PRADEEP TALWANI Principal Investigator DEPARTMENT OF GEOLOGICAL SCIENCES UNIVERSITY OF SOUTH CAROLINA l COLUMBIA, SOUTH CAROLINA 29208 CONTRACT NO. N622702 9505180550 450511 5 DR ADOCK 0500

y ,

q

,i

<~

.*/ si s .

~

TECHNICAL REPORT 94-4 SEISMIC ACTIVITY NEAR THE V.C. SUMMER NUCLEAR STATION FOR THE PERIOD OCTOBER-DECEMBER,1994 BY PRADEEP TALWANI Principal Investigatoi and 1

Jason S. Cobb DEPARTMENT OF GEOLOGICAL SCIENCES UNIVERSITY OF SOUTH CAROLINA COLUMBIA, SOUTH CAROLINA 29208 i

i CONTRACT NO. N622702 O

s

'. )

.c '

..- INTRODUCTION Analysis of the seismic activity near the V.C. Summer Nuclear Station in South Carolina between October 1 and December 31, 1994 is presented in this report. .

During this period, three events were recorded in the vicinity of the Monticello l Reservoir, all of which were located. All of the events were of relatively low magnitude.

A compilation of the seismic activity and stition performance for the year 1994 is also included at the end of this quarterly report.

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 IL ,

DATA ANALYSIS  :

4 Hypocentral locations have been determined usine " a computer program HYPO 71 '

. (Lee and Lahr,1972). The velocity model used i aarthquake locations is given in Appendix III. . The format of the HYPO 71 oui, . is given in Appendix IV. The event magnitude was determined from the signal duration at JSC 'using the following relation:

M L= -1.83 + 2.04 Log D, l l

where D is the signal duration (seconds). j An estimate of daily energy release was determined using a simplified magnitude (M t.).cnergy (E) relation by Gutenberg and Richter (1956):

Logio E = 11.8 + 1.5 M t.

OBSERVED SEISMICITY DURING OCTOBER-DECEMBER,1994 Seismicity around Monticello Reservoir was low during-the fourth quarter of 1994.

Three events were recorded and located (Figure 2). All events for the quarter were shallow and varied in depth between 1.25 and 1.95 km. The largest event occurred on November 29,1994 at 22:54:28 UTC and had a duration magnitude of 0.6 (Appendix V). All events occurred in the central region of the Monticello Reservoir with two of the events located within the confines of the reservoir proper. All of the event locations were of fair quality (Appendix V). ,

l 1

d 1

r .

f' i 4 .

. 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 i

- (Figure 4).

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 VI. No systematic correlation  ;

was observed between the seismicity and reservoir level fluctuations. .

CONCLUSIONS ,

Seismicity during the fourth quarter of 1994 was low and occurred in the central region of the reservoir with two of the events located within the confines of the reservoir proper. No systematic correlation was observed between the reservoir level fluctuations and the seismicity.

MONTICELLO NETWORK AND SEISMICITY DURING 1994 STATION OPERATION STATUS i

The operational status of the Monticello Network during 1994 is presented in l Figures 7 and 8. The generally high downtime for the Monticello Network during the fourth quarter (Figure 8) is due to a transmitter failure at Parr Tower which made the data relay for the network inoperative, accounting for 55% of the fourth quarter downtime. In addition, station MR05 was inoperative for 55% of the year ,

(Figure 7) which is attributed to a loss of electricity at the site.

SEISMICITY During 1994 twenty-four events were recorded (Appendix VII) around the Monticello Reservoir, all of which were located. 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 central region of the reservoir

2 1

.---v.-,.,w y- r y c..-o e- .

, _ - . - , _ e. , ,. - ..u --- - , . _-.- , - --,. -

.. - . . - - - . .- - .- . - _ =

.0 0

l

. (Figure 6). Every month but June, September and October had locatable events (Figure 9) with duration magnitudes ranging from Mt = -1.2 to Mt= 2.2 (Figure 10 and Appendix VII) and occurring at depths from 0.09 to 3.45 km (Figure 11 and )

Appendix VII). Twenty-two of the located events had magnituder less than Mt= 1.0  :

while two of the events had magnitudes greater than Mt = 1.0 (Figure 10) and most were of good to fiir quality (B or C) (Appendix VII). ,

Seismicity around the Monticello Reservoir in 1994 continued at the relatively low level that has been observed since 1987. Conipared to the 1993 seismicity (Figure 12 and Appendix VIII) more activity was found in the central region of the reservoir while fewer events were found in the southern region (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.

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.

3  ;

, - _ _ . - . y ,._.- -- .. -

_5

.'s Monticello Reservoir Sub-Network

=l I I

- s4A MR07 <

MR10 MR01 0

_._. _ 34.3

+

MR05 JSC 5.0km i l l I o

_ _ 34.2 MR02 A l l l 81.d 81.3 81.3 A Single component

$ 3 component Figure 1. Location of the Monticello Reservoir sub-network stations e

4

Monticello Reservoir Seismicity

.. -81 23.0 22.0 21.0 20.0 19.0 15.0 17.0 16.0 15.0 t t . t , t , t , f . t , I , f 6 i i i i i 6 i i 25.0 i

~ ~

~~ 24.0

' ~

~~ 2 3.0

~~ ~

~ 2 2.0

~ ~

~~ 21.0 ggg

~~ 19.0 i

-- i e.O

-- ~~

17.0

~~

~~ 16.0

~

5km

~~

1 S.O i . i , i , i . i ,

i '

i '

i i '

i i

i i

i 34

( Figure 2. Events located near Monticel'a Reservoir during the period

{ October - December,1994 (stars).

5

~ '

. k' . .

1650 MONTHLY SBSMICITY 800 --

700 --

E 600 -- l N

500 --

400 --

8

5 300 --

m a

@ 200 --

100 --

0- i E  ;

$ih .- . m...

. . a. . . . . I .im .... _ . . .

1977 1979 1981 1983 1985 1987 1989 1991 1993 Figure 3. Earthquakes between impoundment and December,1994.

' ! ~ ,.

CUMULATlVE SEISMICITY

- 8000

-- 7000

-- 6000

-- 5000 I

N / -- 4000 u.

O

-- 3000 5 m

2

-- 2000 k

-- 1000 I  ;  :  :  ; '

. o

'981 1983 1985 ggg, 1989 1991 t993 Figure 4- Cumulative seismicity near Monticello yeservoir since impoundment.

i l

' 1

-' , 425- .

1 424 h,# 5 I" ' ' ' '

[ ,

I 422-421 420 274 287 300 313 326 339 352 365 )

$? 1 3 ' h {

R 0.5 - ' I I

.5 b b O M ' R b ^

0

.E -0.5 1 1 O ,3 274 287 300 313 326 339 352 365

~

$1 4

8 IE e

5 o

=0 274 287 300 313 326 339 352 365 315- l 1 12-U9 5

g6-c 3-0 274 287 300 313 326 339 352 365 j OCTOBER 1994 / NOVEMBER 1994 / DECEMBER 1994 Figure 5. Comparison of daily lake level, changes in lake level, number of I 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.

8

, . i Monticello Reservoir Seismicity l

.. -81 1 23.0 22.0 21.0 20.0 19.0 15.0 17.0 16.0 1 S.0 I , t , I , i t I t , t , I 25.0 4 l 4 l 4 i 6 4 i

• ~ ~~

24.0 l ~

~ 23.0 22.0

• 21.0

• kg

~~ 2On

• g *

• 4* - -

__

• __ , ,,o

~~

~~ 18.0

~~

~~ 15.0

~ ~

Skm

-~

_- 15.0 l

i i

I i

f 6

i I

6 I

i i

f 6

i I

i '

i I 4

i I

4 g

Figure 6. Events located near Monticello Reservoir during the year 1994 (stars) 9 l

' 1 i l i

60 -

I 55 -

50 -

45 -

tu 40 35 -

3 30 -

825 -

, # 20 15 - ,

10 ,

5 0

" i

" i i i i - - - - - - l MRO1 MR02 MROS MR07 MR10 JEC MONTICELLO STATIONS I

Figure 7. Operational status of Monticello Reservoir seismic sub-network stations for 1994.

Y s

l J

10 f .

100 -- -

90 --

80 --

70 --

y 60 --

E 3: 50 --

8 at 40 -- . . .

30 --

20 --

10 --

0-1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 MRO1 MR02 MROS MR07 MR10 JSC Figure 8. Operational status by quarter of Monticello Reservoir seismic sub-network stations during 1994. Quarters and stations designated.

4

-  ?

- -_ =-- - --. - _ _ _ . -- -..

' *- l l-1 .

i i

l

! 1 i

5 l

1 l

5 -- i 4--

3--

E.hiI..n JAN FEB MAR NH MAY JJNE JULY AUG SEP CCT NOV DEC i

Figure 9. Monthly distribution of located earthquakes at Monticello Reservoir during 1994.

12

_..-..___E...__._._.______.___.____________________._________..__________________..__..

s.

4 i

i 12 1

10 8

Q 6 8 *-

@ 4 2

O i i i i

<0.0 0.0 < 1.0 1.0 <2.0 >2.0 MAGNITUDE RANGE 4

is 1

i

) Figure 10. Magnitude ranges of located earthquakes at Monticello

) Reservoir during 1994.

13 i

,n,.,.,,.--.,- .,-., .,,..--------..,- , - -,- -. ,. . . . _ . - - , _ - - . _ . - - - , . . - - - , , . - , - -

__ _ _ _ _ _ . _ . _ _ . ~ . . _ _ . . _ . . . _ _ . . _ _ _ . _ . . _ _ _ _ _ . _ _ _ . . _ - . _ . _ _ _ _ . - _ _ _ _ _ _ . . - _ . _ - _ - . _ _ _ . _ _ _ _ . _

l i

4 l

)

i i

l 8 -

i j 7

<0 -

E5,! 0.0 <.0.5 0.5 < 1.0 1.0 < 1.5 1.5 <2.0 >2.0 DEPTH OF EARTHQUAKE (km) l

\

t l Figure 11. Depth distribution of located earthquakes at Monticello Reservoir during 1994.

}

l i

{ 14 l 1

c Monticello Reservoir Seismicity o

.. -81 23.0 22.0 21.0 20.0 19.0 18.0 17.0 16.0 15.0 t , t , t , t , t , t , i , i , i 6 i i 6 i & i 4 I 25.0 i

24.0 23.0

~~

k ~~ 2 2.0 21.0

-- 204 f .

~~ ~~

19.0

, -- 18.0

~ ~

g ~~ 17.0

~ ~

~~ 16.0

~ "

Skm

-- 15.0 i , i , , , , i , i , i , t , '

34

, s s s s s

n Figure 12. Events located near Monticello Reservoir during the year 1993 (stars).

15

y, f

a, *

,--i, APPENDIX I o STATION LOCATIONS STATION LAT N' LONG W JSC 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' ,

MR07 34 22.23' 81 19.50' MRIO 34*20.18' 81*20.25'.

e 4

0 16

. . . _ _ _.. -.v._, , . . . . . , . . . . _ r , . .

5: . . . ; 1. ; . -

Y 4

APPENDIX II 1

" SEISMIC STATION OPERATIONAL STATUS ,

. OCTOBER 1 - DECEMBER 31,1994' STATION PERCENT DOWNTIME

. MR01 6.5 MR02 6.5 MR05 100

. MR07 6.5 MR10 6.5 JSC 0 l

l i

1 1

17

, , - vn-, - - - - ,e 8 r - --- ,-- --e.--- - ~ .- n,< , - g -- -- , ~

v .. .*.

APPENDIX III MONTICELLO RESERVOIR VELOCITY qODEL 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 1

18 L

,o

• APPENDIX IV MONTICELLO EARTHQUAKES

~

HYPO 71 FORMAT Column 1 Date i Column 2 Origin time (UTC) h.m.sec.

Column 3 Latitude (N) degrees, min.

Column 4 Longitude (W) degrees, min.

Column S 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 l insufficient data.

19 '

n .

e, r- .,,

.y.

.- APPENDIX V MONTICELLO RESERVOIR EARTHQUAKES OCTOBER- DECEMBER,1994 P

DATE ORIGIN LAT N LONG W DEPTH MAG NO GAP DMIN RMS ERH ERZ Q M 941120 342 52.20 34-19.73 81-19.39 1.95 0.01 10 152 1.6 0.03 0.2 0.3 B 1 941129 2254 28.91 34-20.75 81-18.19 1.77 0.63 9 188 1.7 0.02 0.1 0.2 C 1 941215 634 33.31 34-19.75 81-20.88 1.25 -0.24 7 261 1.3 0.04 0.4 0.5 C 1 1

a 1

20

. _ + , , , - , - - - - - - , - - - , _ _ . - . , - . _ _ . , . , - . _, . ,, , -,,.,n. -

.i 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 October 1 - December 31,1994. Dates are given in Julian Calendar.

J.DATE, WL (max) WL(min) WL(avg) WL (ch) # of eqs Energy 274 425 423.6 424.4 0.2 0 0 275 424.4 423.6 424.2 -0.2 0 0 276 424.9 423.9 424.8 0.6 0 0 277 424.9 424.2 424.8 0 0 0 278 424.9 424.1 424.5 -03 0 0 279 424.8 423.9 424.4 0.1 0 0 280 424.4 422.8 423.8 -0.6 0 0 281 424.8 422.8 424 3 0.5 0 0 282 424.5 423.4 424.1 0.2 0 0 283 424.8 423.5 424.4 03 0 0 284 424.6 423.8 424.4 0 0 0 285 424.6 423.8 4243 -0.1 0 0 286 424.5 424 424.2 -0.1 0 0 287 424.6 422.5 423.7 -0.5 0 0 288 424.5 422.6 424.1 0.4 0 0 289 424.4 424.2 424.4 03 0 0 290 424.9 423.9 4243 -0.1 0 0 291 424.8 423.5 424.1 -0.2 0 0 292 424.6 423 423.6 -0.5 0 0 293 424.9 423 423.6 0 0 0 294 424.8 423 423.9 03 0 0 295 424.6 421.7 423.6 -03 0 0 296 424 422.4 423.1 -0.5 0 0 297 424.9 422.2 423.5 0.4 0 0 298 424.9 422.5 424.1 0.6 0 0 299 424.8 423.7 424.4 03 0 0 300 424.8 423.9 424.2 -0.2 0 0 301 424.8 423.7 424.1 -0.1 0 0 302 424.8 423.8 424.6 0.5 0 0 303 424.7 424.1 424.4 -0.2 0 0 304 424.9 422.5 423.9 -0.5 0 0 305 425 422.9 424.5 0.6 0 0 306 424.7 424 424.4 -0.1 0 0 307 424.9 423 3 424.1 -03 0 0 308 424.8 423.5 424 -0.1 0 0 309 424.9 423.7 424.7 0.7 0 0 310 424.9 424.2 424.6 -0.1 0 0 311 424.8 423.6 424.3 -03 0 0 312 424.8 423.9 424.5 0.2 0 0 313 424.8 424.2 424.7 0.2 0 0 314 474.8 423.4 424.1 -0.6 0 0 21

j: lv l

, 0 APPENDIX VI (continusd) i J.DATE WL (max) WL(min) WL(avg) WL (ch) # of eqs Energy 315 424.7 423.4 424.1 0 0 0 316 .. 424.5 422.7 423.8 0.2 0 0 317 424.4 422.7 423.8 0 0 0 318 425 422.7 424.1 0.3 0 0

-319 425 422.8 423.9 0.2 0 0 320 424.9 422.4 423.5 -0.4 0 0 321 424.8 422.2 423.6 0.1 0 0 322 424.6 4223 423.4 4.2 0 0 323 424.7 422.7 424 3 0.9 0 0 324 424.5 424.4 424.4 0.1 1 11.82 325 424.8 423.1 424 -0.4 0 0 326 424.9 423.4 424.5 0.5 0 0 327 424.7 423 424.1 -0.4 0 0 328 425 423 424.6 0.5 0 0 329 424.9 424.7 424.8 0.2 0 0 330 424.7 424.1 424.5 -03 0 0 331 424.2 423.3 423.7 -0.8 0 0 332 424.7 423.8 424.6 0.9 0 0

. 333 424.6 423.6 423.8 -0.8 1 12.75 334 424.6 423.7 424.2 0.4 0 0 335 425 423.8 424.2 0 0 0 336 424.9 422.9 423.5 -0.7 0 0 337 424.9 4233 424.5 1 0 0 338 424.6 423.6 4243 -0.2 0 0 339 424.9 423.7 424.6 0.3 0 0 340 424.7 423.9 424.8 0.2 0 0 341 424.7 424 424 3 -0.5 0 0 342 424.4 424 424.2 0.1 0 0 343 424.6 423.9 424.2 0 0 0 344 424.4 423.9 424 3 0.1 0 0 345 424.4 424 424.3 0 0 0 346 424.9 423 423.9 -0.4 0 0 347 425 423.1 423.7 -0.2 0 0 348 425 423.4 424.4 0.7 0 0 349 424.9 4233 424.2 -0.2 1 11.14 350 424.7 423.5 424.1 -0.1 0 0 351 424.5 423.9 424.2 0.1 0 0 352 424.6 423.9 424.5 0.3 0 0 353 424.7 424.2 4243 -0.2 0 0 354 424.6 423.9 424.1 -0.2 0 0 355 424.4 423.5 423.8 -03 0 0 356 424.1 423.5 423.7 0.1 0 0 357 423.6 423.4 423.5 4.2 0 0 358 423.6 422.9 423.4 3.1 0 0 359 423.1 422.9 423 0.4 0 0

~

360 424.7 423 423.9 L9 0 0 361 424.2 423 424 0.1 0 0 362 424.1 424 424.1 0.1 0 0 363 424 423.8 423.9 -0.2 0 0 3M 423.9 423.6 423.8 -0.1 0 0 365 423.8 423 423.5 -03 0 0 22

q; t a 7 ,. .."

\

APPENDIX VII- -

MONTICELLO RESERVOIR EARTHQUAKES JANUARY - DECEMBER,1994 DATE ORIGIN LAT N LONG W DEPTH MAG NO GAP DMIN RMS ERE ERZ Q M

.940110 1746 0.43 34-19.38 81-20.76 0.81 0.73'10 210 1.7 0.02 0.2 0.2 C 1 940201 254 6.50 34-19.96 81-20.60 0.30 -0.40 10 236 0.7 0.04 0.3 0.3 C 1 940210 552 32.03 34-19.13 81-19.51 3.45 -0.11 6 212 5.7 0.02 1.1. 1.3 C 1 940214 13 7 39.50 34-19.83 81-19.67 2.33 0.12 9 157 1.1 0.04 0.3 0.3 B 1 940318 1048 22.83 34-19.49 81-21.69 2.81 0.21 -6 276 2.6 0.08 1.2 1.5 C 1 940330 2038 34.61 34-19.73 81-19.34 1.80- 0.01 8 168 1.6 0.03 0.2 0.3 B 1 940409 1012 54.96 34-19.71 81-19.48 1.48 0.78 10 119 1.5 0.04 0.2 0.4 B 940430 1341 13.83 34-20.64 81-18.37 2.17 -1.22 7 175 1.7 0.04 0.3 0.4 B 940430 1341 17.47 34-20.49 81-18.27 1.82 -0.40 10 173 1.4 0.03 0.2 0.2 B 1.9 0.10 940430 13 8 30.58 34-19.98 81-19.06 0.57 -0.40 8 103 0.5 1.5 B 940430 1344 6.70 34-20.78 81-17.84 1.81 -0.40 6 198 1.6 0.08 0.6 0.9 C 940510 1230 24.73 34-22.62 81-19.64 1.05 0.01 5 318 0.8 0.01 0.2 0.1 C 940511 513 33.97 34-20.02 81-19.93 0.25 0.68 10 119 0.6 0.06 0.3 0.9 B 940519 1011 19.15 34-20.99 81-20.43 0.81 -0.40 7 222 1.5 0.03 0.5 0.6 C 940723 112 15.94 34-21.83 81-21.64 0.09 2.16 10 290 3.4 0.04 0.8 1.3 C 1 940725 1211 39.73 34-22.33 81-19.60 2.21 0.21 8 344 0 2 0.04 1.4 0.3 C 1 940728 16 4 31.50 34-18.29 81-15.70 2.68 1.54 6 213 2.8 0.03 2.2 0.8 C 1 940809 945 47.63 34-19.89 81-20.35 0.91 -0.86 4 248 0.6 0.03 C1 940810 233 20.48 34-22.29 81-21.35 2.95 -0.60 6 332 4.3 0.06 2.2 1.8 C 1 940814 1258 19.27 34-19.45 81-20.21 1.12 -1.22 4 232 1.3 0.01 C1

, 940830 1257 47.58 34-22.33 81-20.31 3.00 -0.86 4 314 1.2 0.03 C1 941120 342 52.20 34-19.73 81-19.39 1.95 0.01 10 152 1.6 0.03 0.2 0.3 B 1

, 941129 2254 28.91 34-20.75 81-18.19 1.77 0.63 9 188 1.7 0.02 0.1 0.2 C 1 941215 634 33.31 34-19.75 81-20.88 1.25 -0.24 7 261 1.3 0.04 0.4 0.5 C 1 t

A I

23 v.

g .; ':

5 ..

7'" APPENDDC VIII ,

MONTICELLO RESERVOIR EARTHQUAKES JANUARY-DECEMBER,1993 s

DATE ORIGIN LAT N LONG W DEPTH MAG No GAP DMIN RMs ERR ERZ QM 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 930112 043 25.39 34-17.52 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 558 29.53 34-23.09 81-19.60 1.00 0.01 8 322 1.6 0.16 2.6 1.8 D1 930430 1615 12.49 34-22.09 81-20.72 0 16 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 C.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 10.4 0.02 0.4' O.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 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 2 e

l l

24 i y -- ,, -- ,,