STUDY OF HISTORIC SEISMOGRAMS OF NUCLEAR EXPLOSIONS FROM

NOVAYA ZEMLYA TEST SITE BY DATA OF THE USSR STATIONS

(T2.3-P16)

Inna Sokolova1, Yuri Kopnichev2

1Institute of Geophysical Research AEC ME RK, Almaty, Kazakhstan 2The Schmidt Institute of Physics of the Earth of the Russian Academy of Sciences , Russia

The Novaya Zemlya Test Site was used in Soviet time for conducting the unique tests of nuclear weapons in different mediums. 130 nuclear explosions with total yield of 265 megatons were conducted at the

Test Site in 1955 – 1990. 1 surface explosion, 85 air explosions, 2 water, 3 underwater and 39 underground (in boreholes, in tunnels) nuclear explosions were conducted at Novaya Zemlya [1-6]. In addition, near the

Test Site there are known tectonic earthquakes and induced earthquakes caused by multi-megaton UNEs. Investigation of the wave pattern of seismic sources from Novaya Zemlya Test Site region is of great

interest for the specialists in the field of nuclear explosions monitoring.

Unfortunately, only few seismic events from Novaya Zemlya Test Site territory were recorded by digital stations. However, the archives of different seismological Organizations accumulated a lot of analogue

seismograms from the Test Site recorded by permanent and temporary stations. In addition, in 1962 a microbarograph that recorded infrasound waves records from multi-megaton air nuclear explosions at

distances ~3500-3700 from the Test Site was installed on the territory of Talgar seismic station. Seismic and infrasound records of nuclear explosions from Novaya Zemlya Test Site are investigation subject of

current work.

MATERIALS AND OBSERVATION SYSTEM.

The Novaya Zemlya Test Site is located in the Russian Federation on the territory of Novaya Zemlya archipelago as a part of Archangelsk region. The archipelago consists of two large islands – northern and

southern separated by Matochkin Shar Strait. The northern island is ~49000 km2, and southern ~33200 km2 [1]. The archipelago extension from north to south is about 750 km, and its width is 140 km. Figure 1

shows the test sites of Novaya Zemlya. 130 nuclear tests were conducted at Novaya Zemlya Test Site in 1955-1990, among them were: 88 air explosions, 3 underwater explosions and 39 underground nuclear

explosions. At zone A (the region of Chernaya inlet) there were kiloton air nuclear explosions, underground nuclear explosions in shafts, and a surface nuclear explosion, 3 underwater and 2 above-water nuclear

explosions. At zone B the underground nuclear explosions were conducted in tunnels (mountainous regions of Moyiseyev and Lazarev). At zone C there were tests of multi-megaton nuclear charges thrown off the

airplanes [1].

The nuclear explosions seismograms accumulated in archives of Central Asia are unique and valuable material for scientific investigations.

Figure 2 shows the location of seismic stations operated in different years which seismograms were used for investigations. The seismograms of these stations are kept mainly in archives of CSE IPE RAS in

Talgar (Complex Seismological Expedition of the the Institute of Physics of Earth), SEME MES RK in Almaty (Seismological Experience-Methodical Expedition)[7], IGR NNC RK at Borovoye seismic station and

IS KR in Bishkek (Institute of Seismology of Kyrgyzstan) [8].

Figure 1. Boundaries of the testing subareas of the Novaya Zemlya Test Site (NZTS). A, B, and C

denote three main areas (zones) of military activity: A = Guba (Bay) Chernaya. Six Nuclear explosions

(underwater, above water, and at the ground surface) were conducted in this area during 1955–1962.

Six underground nuclear tests were carried out in shafts during 1972–1975. B = Guba Mityushikha,

south Bank of Matochkin Shar. This was theare a for under ground nuclear tests conducted in adits

(tunnels). A total of 33 UNTs were exploded in this area in 36 tunnels. C = Sukhoy Nos Cape and its

vicinity. A special zone, chosen for very large atmospheric nuclear explosions, including the most

powerful test (58 mt, 30 October 1961). Military settlements: Belushya (open circle)—administrative

and scientific Center and NZTS head quarters. Rogachevo (open triangle)—settlement and airport,

equipped with along runway for any type of military or civilian planes [1].

Figure 2. The map of seismic stations location (white triangles) which data were used for investigations;

stars – epicenters of nuclear explosions at NZ.

As analog form of recording does not allow to solve tasks requiring digital mathematical processing, the most nuclear explosions seismograms from NZ Test Site were digitized. “NXSCAN” [9] program was used as a software that allows

to digitize the preliminary scanned seismograms in semi-automated mode. The seismograms were digitized with frequency 40 Hz. The fragments of analog seismograms digitized by NXSCAN are kept in SAC format (Seismic Analysis

Code), and after that those are converted into CSS3.0 format (Center for Seismic Studies v.3.0) [10]. In total, 785 seismic records for 55 nuclear explosions at epicentral distances 1270-4410 km were processed (Figures 3, 4).

622

96 5 10

undergroundnuclear explosionatmosphericnuclear explosionabove-waternuclear explosionunderwaternuclear explosion

Figure 3. The diagram of seismograms

distribution by the source type. 1500 2000 2500 3000 3500 4000 4500

0

50

100

150

200

,km

N

Figure 4. The diagram of seismograms

distribution by epicentral distances.

Peculiarities of wave patterns of explosions conducted in different mediums.

Eighty five air nuclear tests were conducted at Novaya Zemlya Test Site from September 24, 1957 to December 25, 1962; total yield of all air explosions was 239.6 Mt. The epicentral distance from the region of atmosphere nuclear explosions

to Central Asia stations was 2600-3800 km; only large atmosphere explosions could be recorded at these distances; the yield of recorded explosions ranged 0.4 – 58 Mt.

The records of air nuclear explosions conducted at Novaya Zemlya Test Site are of low-frequency and have all signs of air explosions: powerful surface waves dominating in amplitude, indistinct P arrival, S/P ratio larger than 1. Figure 5

shows seismic records of air nuclear explosion conducted at 3230 m height, on October 22, 1962, t0=09-06-10.1, =73.4, =54.9, explosion yield Y=8200 kt.

In works [11, 12] is noted that the peculiarity of seismic records of air and surface nuclear explosions recorded by standard long-period seismometers is availability of featured oscillations in seismograms that coincide in arrival time and

form with corresponding records of microbarographs, especially at its initial part. The reason of nuclear explosions acoustic waves recording by a seismometer is ground motion caused by change of ground surface load when air wave passes the

seismometer installation place [11]. 6 records of acoustic wave were found for air explosions in seismograms of Alma-Ata (AAA) and Talgar (TLG) stations.

Figure 6 shows the seismogram of air explosion of October 22, 1962, t0=09:06:10.1, =73.400 N., =54.900 E from AAA station at distance 3550 km, explosion yield was 8.2 Mt. The air wave record for AAA station is visible in vertical

component only and represents an oscillations train with large periods reaching 3 minutes. Propagation velocity is v=(0.332 ± 0.018) km/s.

Figure 6 - Seismogram а) air nuclear explosion, б) acoustic wave of October, 22,

1962, t0=09:06:10.1, =73.400 N., =54.900 E by the station Alma-Ata (AAA) at

distance 3550 km.

Figure 5. Seismograms of air nuclear explosion of

October 22, 1962, t0=09-06-10.1, =73.4, =54.9.

a) b)

In autumn of 1955, 1957 and 1961 at Guba Chernaya inlet of Novaya Zemlya Test Site in Navy forces interests there were 3 underwater torpedo bursts with nuclear charge that were accompanied by military equipment tests. In 1955 the

torpedo was suspended at 12 m depth from a boat that was destroyed by the explosion; in 1957, 1961 the torpedoes with nuclear charges were launched from the bay mouth side. The explosions were conducted at water depth up to 60 m. The last

underwater test at Novaya Zemlya Test Site was conducted on October 23, 1961, t0=10-30-48.0, =73.9, =53.8, at 20 m depth, the charge yield was 4.8 kt. The event was recorded by several stations located in Altay, Kazakhstan and

Kyrgyzstan (Figure 7). The epicentral distance range was 2750-3700 km. P-waves are dominating in all seismograms, first arrival is clear, the signs of first arrivals on vertical component are positive. The record is high-frequency, there are no

surface waves, ratio S/P<1.

Figure 7. The seismograms of underwater test at Novaya Zemlya Test Site

of October 23, 1961, t0=10-30-48.0, =73.9, =53.8, h= 20 m, Y=4.8 kt.

Figure 8. The seismograms of above-water nuclear explosion

of October 27, 1961, t0=08-30-26.6, =70.7, =54.67, height is

1.1 m, yield is 16 kt.

Figure 9. The seismograms of underground nuclear explosion

conducted in a tunnel on October 11, 1980, t0=07-09-57.4, =73.336,

=54.94, h=600 m, yield Y=130 kt.

Using historical seismograms of nuclear explosions conducted at Novaya Zemlya Test Site, the amplitudes and periods of main seismic phases were measured, and mb and MLV magnitudes were calculated. Thus, the catalogues of

international seismic services were added with information previously absent in the catalogues. In total, the magnitudes for 55 explosions conducted in different mediums were calculated. Figure 10 shows the dependence of mb magnitudes

on explosion yield for nuclear explosions conducted in different mediums. It is seen that seismic effect of explosions differs significantly depending on a source type – air explosions have the lowest seismic effect, above-water explosion has

intermediate position between air and underground nuclear explosions, and underwater explosion has the largest seismic effect.

Figure 11 shows the dependence of MLV magnitude on explosion yield for nuclear explosions conducted in different mediums. Seismic effect of underground nuclear explosions is much larger than for air explosions.

For underground nuclear explosions:

mb=4,09+0,75*lg(Y(kt)), correlation coefficient R=0.95.

MLV=2,74+1,05* lg(Y(kt)), correlation coefficient R=0.93.

For air nuclear explosions:

mb=0,997+0,99*lg(Y(kt)), correlation coefficient R=0.83.

MLV=3,83+0,34* lg(Y(kt)), correlation coefficient R=0.61.

10 100 1000 10000

3,6

3,8

4,0

4,2

4,4

4,6

4,8

5,0

5,2

5,4

5,6

5,8

6,0

6,2

6,4

6,6

6,8

7,0

1

2

3

4

5

6

Y(kt)

mb

100 1000 10000

4,4

4,6

4,8

5,0

5,2

5,4

5,6

5,8

6,0

6,2

6,4

6,6

1

2

3

4

Y(kt)

MLV

Figure 11. Dependence of MLV

magnitudes on explosion yield for nuclear

explosions conducted in different mediums. 1 –

MLV magnitudes – underground nuclear

explosions, 2- atmosphere nuclear explosions, 3

– regression line for atmosphere nuclear

explosions, 4 – regression line for atmosphere

nuclear explosions.

Figure 10. Dependence of mb magnitudes on

explosion yield for nuclear explosions conducted in

different mediums. 1 – mb magnitude of

atmosphere explosions, 2- underground nuclear

explosions, 3 – above-water explosion, 4 –

underwater explosion, 5 – regression line for

atmosphere nuclear explosions, 6 – regression line

for underground nuclear explosions.

TEMPORAL VARIATIONS OF S-WAVES ATTENUATION FIELD AT THE REGION OF NOVAYA ZEMLYA TEST SITE

Significant temporal variations of attenuation field of short-period shear waves at the region of Semipalatinsk Test Site related to migration of deep fluids as a result of long intensive man-made impact on geological medium were

revealed earlier [13].

The characteristics of attenuation field of short-period shear waves at the region of Novaya Zemlya Test Site were considered. The method based on analysis of relative level of Sn and Pn waves (Sn/Pn parameter) and slope of P-

coda envelops by records of underground nuclear explosions (UNE) recorded by BRVK station was used [14]. The method related to analysis of maximum amplitudes ratio in Sn and Pn (parameter lgASn/APn) was used [14]. The

work [15] shows that Sn group is mainly formed by shear waves reflected from sub-horizontal borders of upper mantle. Amplitudes ratio is used for normalizing as Sn and Pn waves propagate in near traces. In addition, the slope of P-

coda envelop was analyzed. As determined earlier, P-wave coda within the considered distance range is formed mainly by waves propagating near radial plane as a result of exchange scattering of S – P type in focus field [16]. In this

case, coda-waves transverse the crust and upper mantle in the epicenter area with more steep angles, than Sn group [15]. The parameter lg(Ac/Ap) was considered, where Ac is the level of enveloping coda at fixed time moment tc,

calculated from radiation beginning in the focus.

As attenuation depends much on frequency, vertical components of records were preliminary filtered by narrow-band filter (the filter with central frequency 1.25 Hz and band 2/3 octave was used).

Figure 12 shows the records of two UNEs recorded by BRVK station (27.01.1971 and 10.08.1978). It is seen that in 7.5 years after the first explosion, the relative level of Sn group decreased sharply, and amplitudes attenuation

velocity increased significantly in P-wave coda.

Figure 13 shows dependence of Sn/Pn parameter on time. The graph shows that, in whole, Sn/Pn values decrease with time, dependence is non-monotone. The episodes of average values increase of Sn/Pn were observed in 1973-

1975 and 1981-1983 (to -0.72 and -0.83, respectively) accompanied by the intervals of its sharp drop in 1976-1978 and 1984-1990 (up to -1.07 and -1.06).

Figure 14 shows common P-coda envelops in different time intervals. It is seen that the envelops slope change is also non-monotone: in 1973-1975 and 1981-1983 it decreased sharply, and in other time intervals it increased. С/Р

parameter (tc=400 s) varies from -0.65 in 1973-1975 to -1.36 in 1976-1980.

Figure 12. The examples of UNE

records from Novaya Zemplya

Test Site. The upper trace is the

explosion of 27.01.1971 г., lower –

10.08.1978. BRVK station,

channel 1.25 Hz. Arrows –

moments of Pn and Sn waves

arrival.

1965 1970 1975 1980 1985 1990

-1,25

-1,20

-1,15

-1,10

-1,05

-1,00

-0,95

-0,90

-0,85

-0,80

-0,75

-0,70

-0,65

years

S/P

Figure 13. Dependence of average values of Sn/Pn on time for

Novaya Zemlya Test Site (by records of UNE). Average values and

standard deviations for UNE (solid signs) and earthquakes are

shown. Horizontal lines – intervals of data averaging.

Figure 14. Common envelops of P-

coda for UNE (NZ test site) in

different time intervals [15].

Dashed lines – the envelop for

period 1967-1969. BRVK station.

The obtained data show significant increase of S-wave attenuation with time at the traces from the Test Site to BRVK station. As the station is located in low-seismicity area characterized by relatively weak attenuation of S-

waves, the main variations of attenuation field should be in the earth crust and upper mantle of the Test Site region [14].

Non-monotone changes of attenuation field parameters at the region of Novaya Zemlya Test Site are probably caused by large energy released after UNEs. The sharpest decrease of Sn/Pn parameter was observed in 1976-

1978, immediately after series of the largest explosions. Large variations of C/P parameter for Novaya Zemlya Test Site (in comparison with Sn/Pn) are probably caused by fluids raising at the test site region, and due to this

dynamic characteristics of the waves traversing the crust and upper mantle with steeper angle change significantly.

The obtained data provide new evidences that long intensive man-made impact is able to change the medium characteristics at quite large depths of the earth crust and upper mantle. Earlier, such evidences were obtained

for the regions of Semipalatinsk and Nevada Test Sites [13,17]. Note that existence of temporal variations of shear waves attenuation field should be considered during works related to discrimination of UNE and earthquakes.

CONCLUSION

Historic seismograms of nuclear explosions and earthquakes occurred on the territory of Novaya Zemlya Test Site were acquired and digitized by the Complex Seismological Expedition IPE RAS and by the Institute of

Geophysical Researches RK; the database of events records from the Test Site was created for epicentral distance 1270-4390. It includes seismic records of air, underground nuclear explosions, and underwater nuclear explosion

conducted within “Korall” exercise and above-water nuclear explosion. In addition, infrasound records of waves from large air nuclear explosions recorded by the microbarograph installed at Talgar seismic station at distance

~3600 km from the Test Site were acquired and analyzed.

Kinematic and dynamic parameters of nuclear explosions records conducted in different mediums (air, under water and underground) were investigated by the digitized records from events at Novaya Zemlya Test Site;

specific features of wave pattern for each class of events were found, mb and MLV magnitudes were calculated, nuclear explosions catalogue was added with new explosions parameters for Novaya Zemlya Test Site.

It was found that average values of Sn/Pn decreased significantly on UNEs records from the Test Site region from the end of 1960-s to 1990-s, and the slope of P-coda envelops increased. It is supposed that the revealed

effects are due to migration of deep fluids as a result of long intensive man-made impact.

REFERENCE

1. Khalturin V.I., Rautian T.G., Richards P.G., Leith W.S. A Review of Nuclear Testing by the Soviet Union at Novaya Zemlya, 1955-1990. // Science and Global Security, 2005, V.13., p. 1-42.

2. Mikhailov V.N. ed. USSR Nuclear weapons tests and peaceful nuclear explosions, 1949 through 1990 // RFNC-VNIIEF. 1996. Sarov. 96 p.

3. Dyubasov Yu.V., Matyushenko A.M., Mikhailova V.N. Nuclear explosions of the USSR. Northern Test Site. Reference publication. // St. Petersburg, Published by V.G. Khlopin Radium Institute. 1999. 163 Pp.

1. Logachyov V.A. et al. The Test Site at Novaya Zemlya. General and radiological safety after nuclear tests. Facts, evidences, recollections. // M. Published by AT. 2000. 485 Pp.

2. Adushkin V.V. Leith W. The containment of Soviet underground nuclear explosions // U.S.Geological Survey Open File report 01-0312(2002), 52 p.

3. Internet resource: Nuclear Tests--Databases and Other Material http://www.johnstonsarchive.net/nuclear/tests/index.html.

4. N.N Mikhailova., A.K. Kurskeev Present Status of the Network for Seismic Observation in Kazakhstan. // Journal of earthquake prediction research. - 1995. – v. 4, N 4, Р. 497 506.

5. Beryozina A.V., Pershina Ye. V., Volkhina Ye. T. Archive of analog seismograms of Kyrgyzstan for nuclear explosions monitoring tasks // Vestnik NNC RK. 2013. V.2 P. 44-49.

6. NXSCAN. Manual. IRIS, 1992.

7. J. Anderson, W.E. Center for seismic studies. Version 3 Database: Schema reference manual. / J. Anderson, W.E. Farell et al. // Technical Report C90-01, Arlington. - 1990.

8. Pasechnik I.P. Characteristics of seismic waves at nuclear explosions and earthquakes // Moscow. Science. 1970. 194 Pp.

9. Vasilyev A.P. To the history of infrasound detection method of nuclear explosions // Vestnik NNC RK. Issue 2. 2004.

10. Adushkin V.V., Khristophorov B.D. Nuclear explosions in Guba Chyornaya waters // Nuclear explosions in the Arctic region. Institute of Strategic Stability. The Federal Atomic Energy Agency (Rosatom).

11. Kopnichev Yu.F., Sokolova I.N. Spatial-temporal variations of shear waves attenuation field structure at Semipalatinsk Test Site region // Earth Physics. 2001. #11. Pp.73-86.

12. Kopnichev Yu.F., Sokolova I.N. Temporal variations of short-period S-waves attenuation field at the regions of Novaya Zemlya and Lop Nor Test Sites // Vestnik NNC RK. 2012. Issue 2. Pp.96-100.

13. Kopnichev Yu.F. The nature of short-period seismic fields at distances up to 3000 km / Kopnichev Yu.F., Arakelyan A.R.//Volcanology and seismology. 1988. #4. Pp. 77-92.

14. Koper K. Array analysis of regional-distance P-coda in South Asia / K. Koper, A. Fatehi // Bull. Seismol. Soc. Amer. 2009. V. 99. N 4. P.2509-2522.

15. KopnichevYu.F., Sokolova I.N., Sokolov K.N. Spatio-Temporal Variations in the Structure of the Attenuation Field of the S-Wave in the Region of Nevada Nuclear Test Site // Izvestiya, Physics of the Solid Earth, 2013, Vol. 49, No. 6, pp. 786–795.

16. Kedrov O.K. Seismic methods of nuclear explosions monitoring // M. IPE RAS. 2005. 420 Pp.

In autumn of 1957, 100 m away from the coast of Guba Chernaya inlet there was a near-ground explosion with yield 32 kt installed on a tower of 15 height. In 1961 and 1962 there were above-water torpedo bursts; the torpedoes with nuclear

charge were launched from submarines from bay mouth side. The explosions were conducted at water depth up to 60 m. The aim of the tests was try-out of nuclear charges and Navy forces armament, determination of main physical characteristics

and affecting factors of underwater nuclear explosions at shallow water, military equipment tests using especially developed measuring instruments [13]. One of the above-water explosions was recorded by stations located in Altay, the epicentral

distance range was 2660-2810 km. Figure 8 shows the seismograms of above-water explosion of October 27, 1961, t0=08-30-26.6, =70.7, =54.67, height 1.1 m, yield 16 kt. Note that the explosion was quite small to be recorded at such distances,

thus its record is not clear, first arrival of P-wave is hardly seen on seismic noise background.

Underground nuclear explosions at Novaya Zemlya Test Site were conducted in 1964-1990, there were 39 UNEs, 33 of them were conducted at the northern site near Matochkin Shar Strait in 1964-1990, and 6 tests were conducted at the

southern site in 1972-1975 [1]. 622 records of UNEs were acquired and processed from Novaya Zemlya Test Site, epicentral distance range was 1270-4390 km. Figure 9 shows the seismograms of underground nuclear explosion conducted in a

tunnel on October 11, 1980, t0=07-09-57.4, =73.336, =54.94, h=600 m, yield Y=130 kt. All seismic records are high-frequency, in records P-wave is dominating in amplitude, first arrival is clear, signs of the first arrivals in vertical component are

positive, ratio S/P<1.