NORTH-KOREAN NUCLEAR EXPLOSIONS OF 2006, 2009

(T2-P50)
NORTH-KOREAN NUCLEAR EXPLOSIONS OF 2006, 2009, 2013 BY DATA OF KAZAKHSTAN MONITORING NETWORK
Mikhailova N.N., Sokolova I.N., Aristova I.L.
Institute of Geophysical Research, Kazakhstan
Table2. Kinematic and dynamic characteristics of May 25, 2009 explosion seismic records by data of the RSE IGR seismic stations.
Since 1994 the monitoring network of the RSE IGR that includes 4 small aperture, one mid-aperture, and one large-aperture
seismic arrays, 7 three-component stations and 2 infrasound arrays (Figure 1) has been operating successfully on the territory of
Kazakhstan. Owing to good stations location in view of geology and characteristics of seismic noise, well-configured arrays,
location of most stations in boreholes, joint operation of broadband and short-period instruments, all system stations are high
sensitive to regional and teleseismic events. Five Kazakhstan stations are included into the International Monitoring System of the
Comprehensive Test-Ban Treaty Organization (PS23, AS057, AS058, AS059 and IS31) [1]. Data of Kazakhstan stations and its
processing results are transferred to different International and National Data Centers, among them are: IDC, ISC, EMSC, USGS,
GSRAS.
Figure 1. The map of the RSE IGR stations location; 1 – seismic arrays, 2 – three-component seismic stations, 3 – infrasound stations.
Station
, km
MKAR
3739
KURK
3960
True azimuth to the tP
epicenter
82,07
1:02:23.1
85,36
1:01:42.6
KUR*
3968
85,16
1:01:44.1
4,1
VOS
4463
82,58
1:02:23.1
4,73
BVAR
4498
82,52
1:02:22.9
4,15
BRVK
4504
82,48
1:02:23.1
4,45
ZRNK
4591
81,47
1:02:23.1
4,7
KKAR
4738
71,62
1:02:23.1
ABKAR
5303
72,09
1:03:21.8
4,45
AKTO
5395
71,98
1:03:27.9
4,35
mb
4,17
Estimated azimuth, f-k Apparent velocity,
analysis
km/s
89,41
8,66
4,66
85,52
12,59
85,75
11,11
74,07
12,9
*Kurchatov-Cross seismic array.
Note: The stations that recorded all three explosions are in blue.
Figure 6 shows the recording system of the third North Korean nuclear explosion of February 12, 2013. The clear signal was recorded
at all stations except three-component station KNDC in Almaty. The records of vertical component of three-component broadband
instruments (filter with central frequency of 1.25 Hz) are shown in Figure 7. Only arrivals of P and PcP are clearly seen. Other seismic
phases are absent. Table 3 shows kinematic characteristics and magnitude of seismic event by data of these stations.
On February 12, 2013 Kazakhstan stations recorded a nuclear test conducted by North Korea. Operative data processing was
conducted at Kazakhstan National Data Center. This is third test conducted by North Korea and recorded by Kazakhstan stations network
(10.9.2006, 05.25.2009, 02.12.2013). The epicentral distances range from Kazakhstan stations to Punggye-ri Test Site is 3725 – 5350 km,
azimuth’s range is small – 13 degrees. Data were used by different seismological agencies to determine the explosions parameters.
Figure 2 shows the recording system of the first North Korean nuclear test of October 9, 2006 [2].
Kazakhstan stations data are transferred to some International Data Centers (USGS, IDC, GFZ) in real time, where they are used for the
sources parameters assessment jointly with other seismic stations of the world. In addition, KNDC sends seismological bulletins with
Kazakhstan stations processing results to some International Seismological Agencies (ISC, GSRAS, EMSC) that are used to determine
seismic events parameters. Table 4 shows the parameters results of North Korean explosions determined by different international
seismological centers using Kazakhstan stations data [4-7]. The Table also shows the localization results made by KNDC, although, it was
possible to state, a priori, that localization accuracy by Kazakhstan stations only will be lower than using data of global monitoring
networks. All Kazakhstan stations are located in narrow azimuth range, and large distances.
Three seismic arrays – ABKAR, MKAR and Kurchatov-Cross of the RSE IGR network stations recorded all three explosions.
Comparison of North Korean explosions parameters by the same stations of the network aimed at assessment of relative difference of
magnitudes of three explosions is of large interest. Figure 8 shows the seismograms of North Korean explosions on vertical components of
seismic arrays elements ABKAR, MKAR and Kurchatov-Cross. Table 5 shows the comparison of amplitudes fluctuations on three
components for three nuclear explosions by seismic arrays that recorded all three explosions – Akbulak, Makanchi, and Kurchatov-Cross
(during the second explosion the three-element KUR21 of Kurchatov-Cross did not operate, other elements KUR01-KUR20 operated
properly). All stations show natural increase of the explosions amplitudes that testifies the explosions yield increase – the second
explosion was larger than first one, the third one was larger than second one. This fact stipulated the increase of stations number that
recorded each subsequent explosion.
Table 5. Comparison of fluctuations amplitudes by three components for three nuclear explosions by stations Akbulak and Makanchi
Stations
ABKAR
MKAR
KUR
Figure 6. Mutual location of the NNC RK stations (triangles) and the epicenter of the nuclear explosion in North Korea (star).
Figure 2. Mutual location of the RSE IGR stations (triangles) and the nuclear test epicenter in North Korea (star). Red triangles – stations
that have good records of the nuclear explosion and which data were transferred to the International Centers; white triangles – that did not
record the explosion.
The most distinct signal from the first nuclear test was recorded by Akbulak seismic array and three subarrays of large aperture
system Borovoye – Vostochnoye, Chkalovo, Zerenda. Less distinct arrivals were at the stations Kurchatov-Cross and Makanchi. Figure 3
shows the records of vertical component of 3-component broadband instruments after applying the filter with central frequency of 1.25 Hz
(the filter width is 2/3 octaves at the level of -3dB from maximum). Only P-wave arrivals are distinct. Other seismic phases are absent.
Table 1. Kinematic and dynamic characteristics of October 9, 2006 explosion seismic records.
MKAR
KUR*
VOS
CHKZ
ZRNK
ABKAR
3746
3974
4469
4481
4598
5310
True azimuth
to epicenter
82,06
85,14
82,55
83,41
81,44
72,07
tP
mb
01:42:11.5
01:42:28.5
01:43:05.6
01:43:07.1
01:43:15.4
01:44:07.2
3,79
3,97
3,95
3,87
3,9
3,82
Estimated azimuth, Apparent
f-k analysis
(km/s)
89,17
11,04
85,39
11,76
velocity
Station
, km
MKAR
MAKZ
KURK
KUR*
PDGK
KNDC
OTUK
BVAR
BRVK
KKAR
ABKAR
AKTO
3744
3768
3965
3972
4036
4237
4455
4502
4508
4743
5308
5399
True
azimuth
82,02
81,86
85,3
85,11
75,72
74,49
78,14
82,46
82,42
71,58
72,04
71,93
tP
mb
3:04:33.7
3:04:35.6
3:04:50.3
3:04:51.5
3:04:56.1
3:05:13.9
3:05:28.0
3:05:30.6
3:05:31.4
3:05:48.6
3:06:28.8
3:06:35.1
4,67
4,73
5,08
4,6
4,79
* Kurchatov-Cross seismic array.
4,48
4,55
4,67
4,61
4,84
4,77
Estimated azimuth, Apparent velocity, km/s
f-k analysis
89,6
10,28
85,55
12,49
84,07
13,19
71,08
75,63
12,57
13,03
Note: The stations that recorded all three explosions are in blue.
Table 4. The parameters of three North Korean nuclear explosions by data from different seismological centers.
76,02
15,54
*Kurchatov-Cross seismic array.
Note: the stations that recorded all three explosions are blue.
Figure 4 shows the recording system of the second North Korean nuclear explosion of May 25, 2009 [3]. Almost all stations except
three-component KNDC station in Almaty and KKAR seismic array recorded a distinct signal. Figure 5 shows the records of vertical
component of 3-component broadband instruments after applying the filter with central frequency of 1.25 Hz. Arrivals of P and PcP waves
are clearly seen. Other phases are absent. Table 2 shows kinematic characteristics and magnitude of the seismic event by data of these
stations.
Figure 4. Mutual location of the NNC RK stations (triangles) and the epicenter of North Korean nuclear explosion (star).
Figure 5. The records of the nuclear explosions of May 25, 2009 by vertical
components of the NNC RK stations. Filter is 1.25 Hz.
3 explosion, 2013
N,
E,
Z,
nm
nm
nm
1.8
6.1
8.4
1.6
4.0
6.2
12.8 3.0 23.3
Figure 7. Records of the nuclear test of February 12, 2013 by vertical components of the RSE IGR stations. Filter is 1.25 Hz.
Figure 3. Records of North Korean explosion of October 9, 2006 on vertical components of Kazakhstan stations. Filter 1.25 Hz.
Table 1 shows kinematic characteristics and magnitude of seismic event by these stations.
, km
2 explosion, 2009
N,
E,
Z,
nm
nm
nm
1.0
2.1
3.4
1.5
1.4
1.8
The magnitudes increment of the second explosion in comparison with the first one by all three stations coincide and is mb(2009)mb(2006)~0.6, third with second mb(2013)-mb(2009)~0,4 (Table 6). As for mb magnitude with solutions of other International Centers,
magnitudes understating is observed by the RSE IGR stations, that is, probably, due to processing peculiarities at KNDC. Before the
amplitudes measure, a narrow-band filter SKM was applied for mb magnitude calculation. For example, mb magnitude difference with
NEIC solution is 0,2-0,4 (Table 4).
Calculated azimuths to epicenter and observed ones were compared by f-k analysis results (Table 6). ABKAR seismic array shows
systematic deviation of observed azimuth in comparison with calculated one, the difference is 3.2. MKAR seismic array shows identical
azimuths residual for all three explosions, that is 7.3. At Kurchatov-Cross seismic array the observed and calculated azimuth was almost
the same for all three explosions, the difference was 0.4. Thus, Kurchatov-Cross seismic array can be considered as a basic one for North
Korean Punggye-ri Test Site area; to enhance localization accuracy of other stations, corrections for azimuths are to be applied.
a)
Table 3. Kinematiс and dynamic characteristics of explosion seismic records of February 12, 2013.
Station
1 explosion, 2006
N,
E,
Z,
nm
nm
nm
0.5
0.5
0.8
0.3
0.1
0.4
0.4
0.9
1.5
b)
c)
Figure 8. Comparative analysis of North Korean nuclear tests by data of RSE IGR (up – down: 10/06/2006, 05/25/2009, 02/12/2013). a)
ABKAR station, b) KUR20 element of Kurchatov-Cross seismic array, c) MKAR station. Z-component.
Table 5. Parameters of three North Korean tests by data of ABKAR, MKAR, KUR20 stations.
10.09.2006
05.25.2009
02.12.2013
10.06.2006
05.25.2009
02.12.2013
10.06.2006
05.25.2009
02.12.2013
Station
ABKAR
MKAR
KUR20*
Azimuth
76.02
74.07
75.63
89.17
89.41
89.6
85.39
85.52
85.55
 AZ
3.95
1,98
3.59
7.11
7.34
7.58
0.25
0.36
0.44
Amp,nm
0.8
3.4
8.4
0.4
1.8
6.2
1.2
2.0
7.8
mb
3.82
4.45
4.84
3.48
4.17
4.67
3.54
4.1
4.6
mb-mb(2006)
0
0,63
1,02
0
0,69
1,19
0
0,56
1,06
mb-mb(NEIC)
-0,5
-0,3
-0,3
-0,8
-0,5
-0,4
-0,8
-0,6
-0,5
*element of Kurchatov-Cross seismic array
UNE
Source
Origin time,
h.,min.,s.
Latitude,
N
Longitude,
E
Number of
stations
mb
Kazakhstan stations participated in processing
10.09.2006
GS RAS (Russia)
01:35:26.0
41.35
128.96
11
4.0
MKAR
05.25.2009
GS RAS (Russia)
00:54:40.9
41.29
129.07
51
5.0
MKAR,KURK,VOS,BRVK, ZRNK,
ABKAR, AKTO
02.12.2013
GS RAS (Russia)
02:57:49.4
41.31
129.1
70
5.3
MKAR, MAKZ, KURK,PDGK, OTUK, BRVK, KKAR,
ABKAR, AKTO
10.09.2006
RSE IGR
01:35:30.7
41.105
128.518
6
3.9
KUR, ZRNK, VOS, CHKZ, BRVK, ABKAR
05.25.2009
RSE IGR
00:54:43.2
41.386
129.139
11
4.5
MKAR, KURK, KUR, VOS, BRVK, BVAR, ZRNK,
ABKAR, AKTO, CHKZ, KNDC, KKAR,
02.12.2013
RSE IGR
02:57:53.3
41.554
128.997
12
4.7
ABKAR, AKTO, BRVK, BVAR, KKAR, KURK, KUR,
MAKZ, MKAR, OTUK, PDGK, KNDC
10.09.2006
NEIC (USA)
01:35:28.0
41.294
129.094
31
4.3
CHKZ,ZRNK, BRVK, MKAR
05.25.2009
NEIC (USA)
00:54:43.3
41.306
129.029
75
4.7
MKAR, KURK, BRVK, BVAR, AKTO
02.12.2013
NEIC (USA)
02:57:51.4
41.308
129.076
168
5.1
MKAR, MAKZ, KURK, BRVK, KKAR, ABKAR
10.09.2006
IDC (REB)
01:35:27.6
41.312
129.019
22
4.1
MKAR
05.25.2009
IDC (REB)
00:54:42.8
41.311
129.046
59
4.5
MKAR, KUR, BVAR, AKTO
02.12.2013
IDC (REB)
02:57:50.8
41.301
129.065
51
4.9
MKAR, KUR, BVAR, AKTO
References
1.Mikhailova N.N., Sinyova Z.I., Sokolova I.N. Kazakhstan monitoring system of the Institute of Geophysical Researches of National
Nuclear Center and its capabilities // Seismic prediction observations on the territory of Azerbaijan/RCSS NASA. – 2012. – P.329 –
336.
2.Mikhailova N.N., Sokolova I.N. North Korean nuclear test of October 9, 2006 by data of Kazakhstan and global monitoring systems
// Vestnik NNC RK. Vol. 1. 2008. P. 17-26.
3.Mikhailova N.N. North Korean nuclear test of May 25, 2009 by data of Kazakhstan monitoring system // Vestnik NNC RK. – 2009. –
Vol. 3. P. 17 – 21.
05.25.2009
EMSC (France)
00:54:44.5
41.31
128.98
126
4.8
MKAR, KURK, BRVK
4.Internet resource http://www.isc.ac.uk.
02.12.2013
EMSC (France)
02:57:51.4
41.32
128.99
514
5.0
ABKAR, AKTO, BRVK, BVAR, KKAR, KURK, MAKZ,
MKAR, OTUK, PDGK
5.Internet resource http://earthquake.usgs.gov/earthquakes/eqarchives/epic.
6.Internet resource http://www.ceme.gsras.ru/ccd.htm
Conclusion.
1. North Korean nuclear explosions of October 9, 2006, May 25 2009 and February 12, 2013 were successfully recorded by Kazakhstan
seismic network and global seismic networks. All determinations of the epicenter location conducted in International Data Centers are
of high accuracy (several kilometers).
2. By data of Kazakhstan monitoring stations, corrections for azimuths to epicenters of North Korean nuclear explosions were calculated,
as well as magnitudes increments for three explosions.
3. Significant progress in all monitoring parts – detection, localization and identification of the explosion source was noted for national
and international monitoring systems. Contribution of Kazakhstan stations into detection and processing of signals was significant, its
data were used in all processing stages in different Data Centers.
7.Internet resource http://www.emsc-csem.org