ML20072S647
| ML20072S647 | |
| Person / Time | |
|---|---|
| Site: | Summer  |
| Issue date: | 12/31/1990 |
| From: | Talwani P SOUTH CAROLINA, UNIV. OF, COLUMBIA, SC |
| To: | |
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| References | |
| 90-4, NUDOCS 9104160434 | |
| Download: ML20072S647 (24) | |
Text
r TECHNICAL REPORT 90-4 s
SEISMIC ACTIVITY NEAR 6
THE.V.C. SUMMER NUCLEAR STATION i
l FOR THE PERIOD OCTOBER-DECEMBER,1990 l
l-l BY PRADEEP TALWANI Principalinvestigator Department of geological Sciences Universtity of South Carolina Columbia, SC 29208 l
\\
F
)
t l
l TECHNICAL REPORT 90-4 t
SEISMIC ACTIVITY NEAR THE V.C.
SUMMER NUCLEAR STATION FOR THE PERIOD OCTOBER - DECEMBER 1990 BY PRADEEP TALWANI PRINCIPAL INVESTIGATOR I
i KUSALA RAJENDRAN AND PREETHA SUDHAKAR DEPARTMENT OF GEOLOGICAL SCIENCES l
UNIVERSITY OF SOUTH-CAROLINA
. COLUMBIA, SC 29208 l
CONTRACT NO. N536490 l
l
INTRODUCTION Analysis of the seismic activity near the V.C.
Summer Nuclear Station in South Carolina between October 1 and December 31, 1990, is presented in this report.
During this period, SS events were recorded in the vicinity of Monticello Reservoir, 12 of which were located. The largest event of this quarter occurred on October 30 (12:37:34.55 UTC) and it had a magnitude Mg=1.1.
The~-
were six other events of magnitude Mg = 0.8.
SEISMIC NETWORK Earthquakes during this period were recorded on stations of Monticello Reservoir and South Carolina networks.
The cor.figura-t{on of the stations utilized to locate Monticello events is shown in Figure 1 and station coordinates are listed in Appendix I. The operational status of the stations is given in Appendix II.
In the reporting period, station 007 became fully operational after November 04, 1990. Since then several small events were recorded in its vicinity.
DATA ANALYSIS Hypocentral locations of the events have been determined using the computer program HYPO 71.
The velocity model used in earthquake locations is given in Appendix III.
The format of the output of HYPO 71 is given in Appendix IV (Lee and
- Lahr, 1972).
The event magnitude was determined from the signal duration at JSC, using the following relation:
Mg = -1.83 + 2.04 Log D, where D is the signal duration (seconds).
1 l
h N
MONTICELLO RESERVOIR a
7 i
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h A
JSC STUDY AREA 6
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=
Figure 1.
Location of Monticello Reservoir area showing seismic stations used in locating seismicity.
l 2
An estimate of daily energy release was determined using a simplified magnitude (M ) - energy (E) relation by Gutenberg and g
]
Richter (1956):
Log 10 E = 11.8 + 1.5 M.
g OBSERVED SEIBMICITY FOR THE PERIOD OCTOBER - DECEMBER 1990 During this period 55 earthquakes were recorded, of which 12 were located (Appendix V)
Most of the nonlocatable events occur-red within 5.0 km of station 007 ( Appendix VI).
Many of these events were too small to be recorded by other stations.
The events which were locatable were of poor quality (C and D).
Eight of the twelve located events were in the northern part of the reservoir (Figure 2).
Most of the seismicity during this period occurred in two
- swarms, the first one on November 30, and the second on December 22.
The first sequence consisted of 10 events of wnich four were located to the northwest of the rese'.voir (Figure 2, Appendix V).
The remaining events occurred within 5.1 km of station 007 (Appendix VI). Three events which occurred on December 01 02 (Appendix V) were located to the east of the reservoir and were not considered to be a part of this swarm. The second sequence, which occurred on December 22, was also located to the northwest.
This sequence consisted of 28 small events, of which seven were of magnitude 0.0 and three were of magnitude M=
0.8 g
(Appendices V and VI). One of these three events was located (Appendix V). Those events which could not be located are listed in Appendix VI.
3
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MONTICELLO EARTHOUAKES October - December 1990 OI N'
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0-KILOMETERS' 5
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t 1-1 Figure '2.
. Earthquakes located near Monticello Reservoir during October-December 1990.
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l The. level of seismicity during this period is comparable to that of the previous quarter except for the swarms that occurred to the northwest of the reservoir.
The long term d, cline in seismicity is continuing (Figure 3).
CORRELATION OF RESERVOIR WATER LEVEL WITH BEISMICITY Monticello Reservoir is a pumped storage facility.
Any decrease in reservoir level associated with power generation is recovered when water is pumped back into the reservoir.
There can be normal variations up to approximately five feet per day between the maximum and minimum water levels.
The water level has been monitored to see if there is any carrelation between the daily or seasonal changes in the reservoir level and the local seismicity.
Water level is compared with seismicity in Figure 4.
The top panel shows the average water level; the error bars show the maximum and minimum water levels each day.
The second plot shows the change in average water level from day to day.
The number of events per day and the log of the energy released per day are shown in the lower two histograms.
These charts jnclude all reported earthquakes listed in Appendices V and VI.
The average water
- level, daily changes in water level, number of earthquakes and t'.* energy release are given in Appendix VII.
No systematic correlation was observed between the seismicity and the lakt: level fluctuations.
- However, the increased seismic activity dtring December 22 seems to be associated with n
relatively l arge change in the lake level.
CONCLUBYONS The 1 e.* e l of seismic activity during the last quarter of 5
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DECEMBER 1990: JULIAN DATE rigure 4.
Comparison of daily lake level, variation in lake level, number of earthquakes and log of energy release (ergs per day) at Monticello Reservoir.
Error bars in the top panel indicate daily fluctua-tions in lake level.
7
_ _ _ _ _ _ - -. - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - ~
1990 was low and comparable to that of the previous quarter.
Of particular interest is the low level seismic activity observed to the northwest of the reservoir. 28 of the 65 recorded events in this period occurred on December 22 and they were very close to station 007. The largest event of this quarter which occurred on October 30 (M = 1.1) was within 8.5 km of station JSC.
g
SUMMARY
OF BEIBMICITY IN 1990 A total of 124 events were recorded near Monticello Reservoir during January - December 1990.
The number of events per day recorded during 1990 is chown in Figure 5.
Of the 124 events recorded, only 36 (29%)
were located (Figure 6).
The lower level of recorded seismicity during January March is probably an artifact of poor functioning of stations. During the later part of the year, the operational status was considerably improved.
Most of the nonlocatable events were of short duration (< 5.0 sec) and were not recorded at more than two stations.
This has resulted in the higher ratio of recorded to located events.
All l
of the located events were of C or D quality (Appendix VIII).
A l
majority of earthquakes during this period occurred at shallow l
focal depths (0 - 1.0 km, Figure 7).
The largest earthquake recorded during the year (M =1.9) g 1
occurred on January 29, 1990 (09:23:23.0 UTC).
This event could not be located due to lack of sufficient station coverage. Among I
the located events, seven were of magnitude 2 1.0; 22 were of l
magnitude 2 0.0 and the rest were of magnitude ' O.0 (Appendix VIII).
Spatial distribution of earthquakes during 1990 shows 8
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r-e MONTICELLO EARTHOUAKES January - December 1990 OI 22.0,
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KILOMETERS 5
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Figure 6.
Seismic activity at Monticello Reservoir during 1990.
10
PERCENT 9
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JANUARY. DECEMBER 1090
( TOTAL NUMBER OF EVENTS
- 36)
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Depth distribution of events at Monticello Reservo r (all qualities included).
Figure 7.
during 1990 11
PERCENT e
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6.C JANUARY - DECEMBER 1990
( TOTAL NUMBER OF EVENTS 36)
Figure 7.
Depth distribution of events at Monticello Reservoir during 1990 (all qualities included).
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Seismicity at Monticello during (a) 1987; (b) 198 8 ; (c) 1989; and (d) 1990.
12
occurrence of some earthquakes to the northwest and southeast of the reservoir, regions devoid of seismicity during the previous three years (Figure 8). In those years, most soismicity occurred directly beneath the roscrvoir (Talwani, et al.,
1987; 1988; 1989), whereas in 1990, most seismicity was located outside the reservoir (Figure
- . Another noticeable trend in the roughly north-south alignment of epicentors to the east of the reservoir.
This trend was originally observed in the previous quarter (July 01-September 30, 1990) by Talvani and Rajendran (1990).
REFERENCES Gutenborg, B. and Richter, C.F.
(1956).
Magnitude and energy of earthquakes, Ann. Geof.
9, 1-15.
Leo, W.H.K.
and Lahr, J.C.(1972). A computer program for determining hypocenter, magnitude and first motion pattern of local carthquakes, revision 6 of HYPO 71, U.S. Geological Survey, Open-File Report, 100 pp.
- Talwani, P, Acree
,S. Severance, K.(1587). Soismic act.4.vity near the V.C. Summer Nuclear Station, Technical Report, 67-4, 18p.
- Talwani, P.,
Severance, K.
and
- Arora, V.
(1988).
Soismic activity near V.
C.
Summer Nuclear
- Station, Technical Report 88-4, 18p.
- Talaani, P.
and Rajendran, K.
(1989).
Seismic activity near V.C.
Summer Nuclear Station, Technical Report 89-4, 15p.
- Talwani, P.,
and Rajendran, K.
(1990).
Seismic activity near V.C.
Summer Nuclear Station, Technical Report 90-3, 15p.
13
APPENDIX I S'I ATION LOCATIOND NO.
STN.
LAT. N LONG. W 1
JSC 34*
16.80' B l*
15.60' 2
001 34* 19.91' 81 17.74' 3
002 34* 11.58' 81" 13.81' 4
005 34 16.05' 81' 20.05' 5
007 34" 22.23' 81
19.50' 6
010 34*
20.18' Bf 20.25' 7
09A 34 17.24' Bf 19.75' 4
4 s
14
APPENDI.! II DEIBMIC STATION OPE'tATIONAL STATUd OCTOBER 01 - DECE(DER 31 1990 STATION PERCENT DOWNTIME JSC 11%
001 0%
002 20%
005 14%
007 17's
(
09A 80%
010 95%
e 15 1
i j
APPENDIX III MONTICELLO RESERVOIR VELOCITY MODEL l
1 Volocity 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 O
16
APPENDIX IV MONTICELLO EARTHQUAKE 0
!!YP071 FORMAT Column 1 Date.
Column 2 Origin tiae (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 locato 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.
error of time residuals in Column 10 Rootmeansquarg/NO, sec.
RMS =
Ri 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 epicentral location.
- Statistical interpretation of standard erros involves assump-tions which may not be met in earthquake locations.
Therefore standa.rd errors may not represent actual error limits.
If ERH or ERZ is blank, this means that it cannot be computed, because of insufficient data.
t l
17 l
+
APPENDIX V MONTICELLO EARTHQUAKES OCTOBER - DECEMBER,1990 DATE ORIGIN LAT H LONG W DEPTH MAG NO GAP DMIN RMS ERH ERZ QM 901127 035 36.25 34-17.38 81-19.25 2.72 0.21 6 151 2.8 0.14 1.4 3.7 C1 901110 130 36.54 34-22.33 81-21.82 0.68 0.21 6 286 3.6 0.13 4.6 13.1 D1 901130 8 0 16.39 34-22.33 81-19.60 1.00
-0.24 3 353 0.2 0.04 C1 901130 813 20.54 34-22.33 81-20.26 0.18 0.57 4 281 1.2 0.21 C1 901130 9 8 18.44 34-22.33 81-22.12 1.00 0.82 4 288 4.0 0.15 C1 901201 340 45.00 34-20.68 81-17.21 0.14 0.21 4 212 1.6 0.02 C1 901201 341 23.50 34 20.89 81-17.84 1.00
-0.40 3 201 1.8 0.09 C1 901202 2346 59.53 34-21.57 81-17.84 1.00 0.21 4 223 2.8 0.10 C1 901209 22 1 35.69 34-22.38 81-20.13 1.00 0.44 3 320 1.0 0.00 C1 901210 843 7.84 34-22.33 81-21,45 0.04 0.82 4 284 3.0 0.21 C1 901222 036 29.14 34-22.33 81-19.60 1.00 0.73 5 318 0.2 0.17 48.3 36.9 D1 901222 042 17.61 34-22.33 81-19.60 2.53 0.82 5 318 0.2 0.01 0.9 0.8 C1 e
18
4 APPENDIX VI LIST OF EVENTS WITH S-P
- 2.5 BEC RECORDED AROUND MONTICELLO RESERVOIR DURING OCTOBER-DECEMDER 1990 DATE STATION P-ARRIVAL TIME S-P EP.DIST DUR MAG H
MIN SEC SEC s-p*8.5km SEC 90 10 24 JSC 20 06 13.55 1.15 9.8 10.0 0.2 90 10 28 JSC 08 59 52.50 0.10 0.9 1.0
-1.8 JSC 11 40 46.80 1.00 8.5 5.0
-0.4 90 10 29 JSC 11 55 28.50 0.85 7.2 5.0
-0.4 90 10 30 JSC 12 37 34.55 1.00 8.5 27.0 1.1 90 10 31 JSC 00 39 38.50 0.75 6.4 4.0
-0.6 JSC 00 40 12.70 0.75 6.4 6.0
-0.2 90 11 28 JSC 20 44 05.55 1.65 14.0 10.0 0.2 90 11 29 JSC 02 33 51.00 0.30 2.6 10.0 0.2 90 11 30 007 01 40 43.45 0.55 4.7 6.0
-0.2 007 01 48 31.00 0.50 4.3 5.0
-0.4 007 03 56 05.35 0.60 5.1 4.0
-0.6 007 05 55 19.00 0.50 4.3 7.0
-0.1 007 10 00 15.10 0.60 5.1 5.0
-0.4 007 13 06 48.45 0.50 4.3 5.0
-0.4 90 12 16 JSC 07 48 26.10 0.20 1.7 3.0
-0.9 90 12 22 007 00 38 58.55 0.40 3.4 7.0
-0.1 007 00 39 06.90 0.60 5.1 5.0
-0.4 007 00 39 37.25 3.0
-0.9 007 00 40 16.95 4.0
-0.6 007 00 41 33.55 0.30 2.6 4.0
-0.6 007 00 43 43.60 4.0
-0.6 007 00 43 48.20 0.55 4.7 10.0 0.2 007 00 44 05.95 0.30 2.6 5.0
-0.4 007 00 45 48.85 0.40 3.4 4.0
-0.6 007 00 46 39.45 0.30 2.6 5.0
-0.4 007 00 48 53.65 0.30 2.6 6.0
-0.2 007 00 52 27.35 0.50 4.3 6.0
-0.2 007 00 52 43.85 5.0
-0.4 007 00 53 10.55 0.40 3.4 5.0
-0.4 007 00 53 40.65 0.50 4.3 6.0
-0.2 007 00 54 56.90 0.30 2.6 10.0 0.2 007 03 09 39.70 0.30 2.6 6.0
-0.2 007 03 17 19.50 0.30 2.6 4.0
-0.6 007 03 19 19.55 0.40 3.4 5.0
-0.4 007 03 27 15.50 0.40 3.4 6.0
-0.2 007 03 59 16.80 0.30 2.6 3.0
-0.9 007 05 26 37.85 0.30 2.6 16.0 0.6 007 07 50 54.55 20.0 0.8 007 09 02 54.00 20.0 0.8 007 11 42 24.50 0.30 2.6 7.0
-0.1 007 12 41 49.50 4.0
-0.6 90 12 29 JSC 04 37 20.05 1.20 10.2 20.0 0.8
- Event is very close to 007, (S-P) not clear.
19
%PPENDIX VII
- level, a
Maximum and minimum water levels (ft),chan'ge in water (orgs per day) number of darthquakes and log of energy releaseat Mo ber 31, 1990.
l l
A I
B I
C i
O I
E i_
F I
G
'WL(mas) Wymin) iWLlava)
CHANGE <tio EX ENERGY _
[ DATE 0
0 2
274 424 9l 421.71 423.7-
. _0
_1 3
275 425' 421.8) 423.3; 0 di 0
0 T4 276j 425' 422.31 4?39'
_06~
0 0
{
5 2776 425i 422.1i 423.7:
0.2-0 0
1 424' O 3' O
O
]6 2781 424 71 422.5, 7
2791 424.91 423.2!
424.2i 0.2t
_0 0
8 230I 424 Si 422Ji 4238!
04i 0
0
-9 2811 424 91 420.91 423.1!
0.7i 0;
O
~10 282i 424 6!
421.6!
423.3i 0.2L 0
0 11 283i 424.91 422.11 423.9i 06i 0-0 112 284!
424 di 421.9i 423 81 0 li 04 0
13 285!
424Ja 423.11 423Ji 0.1 i O'
O 14 2861 424.71 423.35 424.51 0.6!
0 0
15 287i 42486 424.71 424.81 0.3i 01 0
16 2881 424.8i 424.81 424.8!
O!
01 0
17 2891 42481 __ 422.3i 424.11 0.7 0-0 18 2901 424 31 422.51 423.6I 0 Si 0_
0 19 291I 424 7' 422.5!
423 di 02!
0 0
20
- 292, 424 6 422,71 424il 0.7i 0
0 21 293i 424' 423 61 423Bi 0.3' 0
0 22 294!
424 2' 423 8!
424.16 0 31 0
0 0
0 23 2?SL 424 7 421.91 423.6i 0 5=
0 0
_24 296!
424' 422li 423di 02!
25 2976 424 1; 423 41 424!
0.61 1
12 1
_y6 2981 424 38 423 9i 424ii 0.1!
0_
0 0-0 27 299i 424:
4231 423.41 0 75
~ Ot 0
28 3001 424' 423i 423.8!
O di 29 301!
424' 423 91 424i 0.2i 2
11.1 130 302i 424 8' 423 2!
424!
O!
1 11.1 31 3038 4245 423 ]i 424 21 02 1
13.4
}32 304!
424 4233i 423Gi 0.6 2_
11 6 33 305i 423 4:
422.61 423.2i 0 Ai 0
0
't4 306) 4256 423di 424.46 1.21 0
0 35 3076 424.9T 424.2i 424.61 0.2' O
O A 3i 0
0
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21
APPENDIX VIII MONTICELLO EARTHQUAKES JANUARY-DECEMBER 1990 DATE ORIG 2N LAT N LO!1G W DEPTH MAG 110 GAP DMI!1 RMS ERH ERZ QM 900402 510 56.97 34-19.07 81-17.84 3.64
-0.11 4 225 1.6 0.10 C1 900506 1141 3.62 34-16.90 81-17.21 1.00
-0.40 3 185 2.5 0.05 C1 900516 1447 13.15 34-22.33 81-19.21 1,69 1.32 4 264 0.5 0.05 C1 900519 627 17.22 34-22.33 81-19.60 1.00 0.21 5 352 0.2 0.18 3.8 D1 900519 643 10.43 34-23.24 81-19.04 1.64 1.18 4 315 2.0 0.09 C1 900526 319 50.01 34-18.77 81-17.84 2.67 0.82 4 202 2.1 0.09 C1 900526 340 37.72 34-19.57 81-17.84 1.54 0.21 4 227 0.6 0.07 C1 900607 1644 34.53 34-20.19 81-17.84 1.00 1.18 3 347 0.5 0.02 C1 900702 1546 19.79 34-19.69 81-20.30 4.89 0.95 5 275 4.0 0.00 0.0 0.0 C1 900705 1431 49.37 34-20.01 81-16.67 1.00 0.21 6 261 1.6 0.18 2.7 7.8 D1 900708 826 23.16 34-20.01 81-17.84 0.08
-0.40 4 343 0.2 0.38 D1 900708 19 1 46.62 34-20.01 81-16.74 1.72
-0.40 4 260 1.5 0.10 C1 900710 1223 32.74 34-15,33 81-17.84 2.95 0.01 4 309 4.4 1.12 D1 900720 1713 26.02 34-20.92 81-15.52 1.57 0.82 4 308 7.6 0.00 C1 900724 2056 34.39 34-19.15 81-18.11 0.23 0.82 6 283 4.3 0.02 0.4 1.0 C1 900801- 034 45.87 34-20.93 81-18.27 1.00 1.02 4 353 8.7 0.03 c1 900914 251 5.18 34-19.78 81-18.10 0.74 1.02 6 302 6.7 0.11 5.9 20.3 D1 900914 256 28.47 34-14.21 81-16.37 0.76
-0.40 4 287 4.9 0.06 C1 900914 315 59.34 34-17.24 81-17.41 5.81 0.91 5 225 2.9 0.00 0.1 0.1 C1
-900914 336 50 69 34-16.41 81-17.21 5.95 0.21 5 172 2.6 0.00 0.1 0.1 C1 900914 354 16.27 34-19.50 81-17.68 0.88 0.91 6 298 5.9 0.12 1.7213.2 D1 900914 528 21.08 34-20.30 81-17.68 0.23 1.18 5 309 7.2 0.09 4.3 11.7 D1 900915 4 1 23.05 34-18.58 81-18.35 0.40 1.54 6 279 5.3 0.05 2.5 6.3 D1 900915 737 39.52 34-20.59 81-19.45 1.00 0.82 3 314 8.4 0.20 C1 902127 035 30,25 34-17.38 81-19.25 2.72 0.21 6 151 2.8 0.14 1.4 3.7 C1 901130 130 36.54 34-22.33 81-21.82 0.68 0.21 6 286 3.6 0.13 4.6 13.1 D1 901130 8 0 16.39 34-22.33 81-19.60.
1.00
-0.24 3 353 0.2 0.04 C1 901130 813 20.54 34-22.33 81-20.26 0.18 0.57 4 281 1.2 0.21 C1 901130 9 8 18.44 34-22.33 81-22.12 1.00 0.82 4 288 4.0 0.15 C1 901201 340 45.08 34-20.68 81-17.21 0.14 0.21 4 212 1.6 0.02 C1 901201 341 23.50 34-20.89 81-17.84 1.00
-0.40 3 201 1.8 0.09 C1 901202 2346 59.53 34-21.57 81-17.84 1.00 0.21 4 223 2.8 0.10 C1 901209 22 1 35.69 34-22.38 81-20.13 1.00 0.44 3 320 1.0 0.00 C1 901210 843 7.84 34-22.33 81-21.45 0.04 0.82 4 284 3.0 0.21 C1 901222 036 29,14 34-22.33 81-19.60 1.00 0.73 5 318 0.2 0.17 48.3 36.9 D1 901222 042 17.61 34-22.33 81-19.60 2.53 0.82 5 318 0.2 0.01 0.9 0.8 C1 22
-