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Zhenxing Yao - One of the best experts on this subject based on the ideXlab platform.
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the 9 september 2016 north korean underground Nuclear Test
Bulletin of the Seismological Society of America, 2017Co-Authors: Lianfeng Zhao, Xiaobi Xie, Weimin Wang, Na Fan, Xu Zhao, Zhenxing YaoAbstract:We characterize the seismic events that occurred in North Korea on 9 September 2016 and South Korea on 12 September 2016. The 9 September 2016 event was identified as an explosion, and the two 12 September 2016 events were identified as natural earthquakes using the P/S (P-and S-wave) spectral ratios, Pg/Lg, Pn/Lg, and Pn/Sn as discriminants. The explosive event was relocated within the North Korean Nuclear Test site using a relative location method and the 2006 North Korea underground Nuclear Test as the master event, and the epicenter was identified at 41.2976 degrees N latitude and 129.0804 degrees E longitude. From the regional Lg and Rayleigh waves, the body-and surface-wave magnitudes for the 9 September 2016 event were calculated as m(b) (Lg) = 4: 8 +/- 0: 2 and M-s = 4: 2 +/- 0: 1. By adopting an empirical magnitude-yield relation for the body-wave magnitude, and assuming that the explosion was fully coupled and detonated at a normally scaled depth, we estimated that the seismic yield was similar to 6 kt, and the uncertainty range was between 3 and 11 kt. If an overburied depth range between 780 and 1200 m was applied, then the yield would be increased to 16-22 kt.
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the 12 february 2013 north korean underground Nuclear Test
Seismological Research Letters, 2014Co-Authors: Lianfeng Zhao, Xiaobi Xie, Weimin Wang, Zhenxing YaoAbstract:Online Material: Figures of Pn waveform comparisons and spectral ratios; tables of Pn differential times and parameters for events used in the study. On 12 February 2013, North Korea conducted its third and the largest Nuclear Test to date in the China–North Korea border area. According to local news, people living in nearby Chinese cities experienced shaking from this explosion. The U.S. Geological Survey (USGS) reported the explosion was located at (41.301° N, 129.066° E) and the magnitude was M 5.1. This event trigged abundant regional seismic phases in northeast China, Korea, and Japan. Because of its large magnitude, the seismic records from this event showed better signal‐to‐noise ratios than those from previous two Nuclear explosions. Illustrated in Figure 1 are broadband regional seismograms at station MDJ for three North Korea Nuclear Tests. These waveforms are highly similar, all are featured with abrupt P ‐wave arrivals, weak Lg phases and well‐developed short‐period Rayleigh waves. We collect the regional waveforms recorded on China National Digital Seismic Network (CNDSN), Global Seismic Network (GSN), and Japan F‐net to investigate the 12 February 2013 North Korean Nuclear Test. Figure 1. Seismograms recorded on MDJ from three North Korean Nuclear Tests in 2013, 2009, and 2006. Illustrated are normalized vertical displacements. The event date, maximum amplitudes, and epicenter distances are listed on the left. Marks on the waveforms indicate apparent group velocities. Note that the waveforms show similar features and display clear impulsive P ‐wave onset, relatively weak Lg phases, and 3–5 s period Rayleigh waves. ### High‐Precision Location By adopting the relative location method (e.g., Schaff and Richards, 2004; Zhang et al. , 2005; Wen and Long, 2010; Murphy et al. , 2013), and using the first North Korean Nuclear Test on 9 October 2006 as the master event, we calculate the origin times and locations of the 25 May 2009 and …
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regional seismic characteristics of the 9 october 2006 north korean Nuclear Test
Bulletin of the Seismological Society of America, 2008Co-Authors: Lianfeng Zhao, Xiaobi Xie, Weimin Wang, Zhenxing YaoAbstract:We investigate the regional seismic signature of the 9 October 2006 North Korean Nuclear Test. Broadband regional data for the Nuclear Test and a group of earthquakes close to the Test site were obtained between December 2000 and No- vember 2006. Epicentral distances from the stations to the Test site are between 371 and 1153 km. We first use these regional events to calibrate the Lg-wave magnitude in the network. Then the network is used to calculate mbLg �� 3:93 for the North Ko- rean Nuclear explosion. Using a modified fully coupled magnitude-yield relation, the yield of the North Korean Nuclear Test is estimated to be 0.48 kt. Because of large uncertainties in the source depth, the estimate is preliminary. The P=S-type spectral ratios Pg=Lg, Pn=Lg, and Pn=Sn are calculated for the Nuclear explosion and a group of earthquakes close to the Test site. At frequencies above 2 Hz, the network-averaged P=S spectral ratios clearly separate the 9 October 2006 explosion from the regional earthquakes. Our result indicates that a single-blast explosion in the North Korea re- gion shows different seismic characteristics from an earthquake. Any well-coupled single-blast explosion detonated in this region with yield similar to that for the North Korean Nuclear Test has a large probability of being identified by a regional seismic network such as the one adopted in this study.
Lianfeng Zhao - One of the best experts on this subject based on the ideXlab platform.
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the 9 september 2016 north korean underground Nuclear Test
Bulletin of the Seismological Society of America, 2017Co-Authors: Lianfeng Zhao, Xiaobi Xie, Weimin Wang, Na Fan, Xu Zhao, Zhenxing YaoAbstract:We characterize the seismic events that occurred in North Korea on 9 September 2016 and South Korea on 12 September 2016. The 9 September 2016 event was identified as an explosion, and the two 12 September 2016 events were identified as natural earthquakes using the P/S (P-and S-wave) spectral ratios, Pg/Lg, Pn/Lg, and Pn/Sn as discriminants. The explosive event was relocated within the North Korean Nuclear Test site using a relative location method and the 2006 North Korea underground Nuclear Test as the master event, and the epicenter was identified at 41.2976 degrees N latitude and 129.0804 degrees E longitude. From the regional Lg and Rayleigh waves, the body-and surface-wave magnitudes for the 9 September 2016 event were calculated as m(b) (Lg) = 4: 8 +/- 0: 2 and M-s = 4: 2 +/- 0: 1. By adopting an empirical magnitude-yield relation for the body-wave magnitude, and assuming that the explosion was fully coupled and detonated at a normally scaled depth, we estimated that the seismic yield was similar to 6 kt, and the uncertainty range was between 3 and 11 kt. If an overburied depth range between 780 and 1200 m was applied, then the yield would be increased to 16-22 kt.
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the 12 february 2013 north korean underground Nuclear Test
Seismological Research Letters, 2014Co-Authors: Lianfeng Zhao, Xiaobi Xie, Weimin Wang, Zhenxing YaoAbstract:Online Material: Figures of Pn waveform comparisons and spectral ratios; tables of Pn differential times and parameters for events used in the study. On 12 February 2013, North Korea conducted its third and the largest Nuclear Test to date in the China–North Korea border area. According to local news, people living in nearby Chinese cities experienced shaking from this explosion. The U.S. Geological Survey (USGS) reported the explosion was located at (41.301° N, 129.066° E) and the magnitude was M 5.1. This event trigged abundant regional seismic phases in northeast China, Korea, and Japan. Because of its large magnitude, the seismic records from this event showed better signal‐to‐noise ratios than those from previous two Nuclear explosions. Illustrated in Figure 1 are broadband regional seismograms at station MDJ for three North Korea Nuclear Tests. These waveforms are highly similar, all are featured with abrupt P ‐wave arrivals, weak Lg phases and well‐developed short‐period Rayleigh waves. We collect the regional waveforms recorded on China National Digital Seismic Network (CNDSN), Global Seismic Network (GSN), and Japan F‐net to investigate the 12 February 2013 North Korean Nuclear Test. Figure 1. Seismograms recorded on MDJ from three North Korean Nuclear Tests in 2013, 2009, and 2006. Illustrated are normalized vertical displacements. The event date, maximum amplitudes, and epicenter distances are listed on the left. Marks on the waveforms indicate apparent group velocities. Note that the waveforms show similar features and display clear impulsive P ‐wave onset, relatively weak Lg phases, and 3–5 s period Rayleigh waves. ### High‐Precision Location By adopting the relative location method (e.g., Schaff and Richards, 2004; Zhang et al. , 2005; Wen and Long, 2010; Murphy et al. , 2013), and using the first North Korean Nuclear Test on 9 October 2006 as the master event, we calculate the origin times and locations of the 25 May 2009 and …
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yield estimation of the 25 may 2009 north korean Nuclear explosion
Bulletin of the Seismological Society of America, 2012Co-Authors: Lianfeng Zhao, Weimin WangAbstract:We collect nine vertical component broadband seismograms from the 25 May 2009 North Korean Nuclear explosion for a regional seismic network in which eight stations also recorded the 9 October 2006 North Korean Nuclear Test. Comparing the observed waveforms and spectra from the two events, we estimate that the amplitudes of the records from the second event are approximately five times those from the first one. Additionally, we use 599 vertical broadband seismograms from 82 regional events recorded on the regional network between December 1995 and May 2009 to calibrate the network Lg ‐wave magnitude. The calibrated network is used to calculate the Lg ‐wave body‐wave magnitude m b( Lg )=4.53 for the 25 May 2009 North Korean Nuclear explosion. Based upon 15 first arrivals from the two North Korea Nuclear explosions, the regional Pn velocity in the northeast China–North Korea region is calculated to be 8.0 km/s. This result, along with the regional geological structures, suggests that the North Korean Test site (NKTS) is located at a relatively stable continental region. We thus use a modified fully coupled magnitude–yield relation to estimate the explosion yield, and the result shows that the yield of the 25 May 2009 North Korean Nuclear Test is approximately 2.35 kt under the minimum burial depth assumption. Online Material: Epicentral parameters, computed m b( Lg ), and corrected m b( Lg ) for 82 events used in the study.
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regional seismic characteristics of the 9 october 2006 north korean Nuclear Test
Bulletin of the Seismological Society of America, 2008Co-Authors: Lianfeng Zhao, Xiaobi Xie, Weimin Wang, Zhenxing YaoAbstract:We investigate the regional seismic signature of the 9 October 2006 North Korean Nuclear Test. Broadband regional data for the Nuclear Test and a group of earthquakes close to the Test site were obtained between December 2000 and No- vember 2006. Epicentral distances from the stations to the Test site are between 371 and 1153 km. We first use these regional events to calibrate the Lg-wave magnitude in the network. Then the network is used to calculate mbLg �� 3:93 for the North Ko- rean Nuclear explosion. Using a modified fully coupled magnitude-yield relation, the yield of the North Korean Nuclear Test is estimated to be 0.48 kt. Because of large uncertainties in the source depth, the estimate is preliminary. The P=S-type spectral ratios Pg=Lg, Pn=Lg, and Pn=Sn are calculated for the Nuclear explosion and a group of earthquakes close to the Test site. At frequencies above 2 Hz, the network-averaged P=S spectral ratios clearly separate the 9 October 2006 explosion from the regional earthquakes. Our result indicates that a single-blast explosion in the North Korea re- gion shows different seismic characteristics from an earthquake. Any well-coupled single-blast explosion detonated in this region with yield similar to that for the North Korean Nuclear Test has a large probability of being identified by a regional seismic network such as the one adopted in this study.
Weimin Wang - One of the best experts on this subject based on the ideXlab platform.
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the 9 september 2016 north korean underground Nuclear Test
Bulletin of the Seismological Society of America, 2017Co-Authors: Lianfeng Zhao, Xiaobi Xie, Weimin Wang, Na Fan, Xu Zhao, Zhenxing YaoAbstract:We characterize the seismic events that occurred in North Korea on 9 September 2016 and South Korea on 12 September 2016. The 9 September 2016 event was identified as an explosion, and the two 12 September 2016 events were identified as natural earthquakes using the P/S (P-and S-wave) spectral ratios, Pg/Lg, Pn/Lg, and Pn/Sn as discriminants. The explosive event was relocated within the North Korean Nuclear Test site using a relative location method and the 2006 North Korea underground Nuclear Test as the master event, and the epicenter was identified at 41.2976 degrees N latitude and 129.0804 degrees E longitude. From the regional Lg and Rayleigh waves, the body-and surface-wave magnitudes for the 9 September 2016 event were calculated as m(b) (Lg) = 4: 8 +/- 0: 2 and M-s = 4: 2 +/- 0: 1. By adopting an empirical magnitude-yield relation for the body-wave magnitude, and assuming that the explosion was fully coupled and detonated at a normally scaled depth, we estimated that the seismic yield was similar to 6 kt, and the uncertainty range was between 3 and 11 kt. If an overburied depth range between 780 and 1200 m was applied, then the yield would be increased to 16-22 kt.
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the 12 february 2013 north korean underground Nuclear Test
Seismological Research Letters, 2014Co-Authors: Lianfeng Zhao, Xiaobi Xie, Weimin Wang, Zhenxing YaoAbstract:Online Material: Figures of Pn waveform comparisons and spectral ratios; tables of Pn differential times and parameters for events used in the study. On 12 February 2013, North Korea conducted its third and the largest Nuclear Test to date in the China–North Korea border area. According to local news, people living in nearby Chinese cities experienced shaking from this explosion. The U.S. Geological Survey (USGS) reported the explosion was located at (41.301° N, 129.066° E) and the magnitude was M 5.1. This event trigged abundant regional seismic phases in northeast China, Korea, and Japan. Because of its large magnitude, the seismic records from this event showed better signal‐to‐noise ratios than those from previous two Nuclear explosions. Illustrated in Figure 1 are broadband regional seismograms at station MDJ for three North Korea Nuclear Tests. These waveforms are highly similar, all are featured with abrupt P ‐wave arrivals, weak Lg phases and well‐developed short‐period Rayleigh waves. We collect the regional waveforms recorded on China National Digital Seismic Network (CNDSN), Global Seismic Network (GSN), and Japan F‐net to investigate the 12 February 2013 North Korean Nuclear Test. Figure 1. Seismograms recorded on MDJ from three North Korean Nuclear Tests in 2013, 2009, and 2006. Illustrated are normalized vertical displacements. The event date, maximum amplitudes, and epicenter distances are listed on the left. Marks on the waveforms indicate apparent group velocities. Note that the waveforms show similar features and display clear impulsive P ‐wave onset, relatively weak Lg phases, and 3–5 s period Rayleigh waves. ### High‐Precision Location By adopting the relative location method (e.g., Schaff and Richards, 2004; Zhang et al. , 2005; Wen and Long, 2010; Murphy et al. , 2013), and using the first North Korean Nuclear Test on 9 October 2006 as the master event, we calculate the origin times and locations of the 25 May 2009 and …
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yield estimation of the 25 may 2009 north korean Nuclear explosion
Bulletin of the Seismological Society of America, 2012Co-Authors: Lianfeng Zhao, Weimin WangAbstract:We collect nine vertical component broadband seismograms from the 25 May 2009 North Korean Nuclear explosion for a regional seismic network in which eight stations also recorded the 9 October 2006 North Korean Nuclear Test. Comparing the observed waveforms and spectra from the two events, we estimate that the amplitudes of the records from the second event are approximately five times those from the first one. Additionally, we use 599 vertical broadband seismograms from 82 regional events recorded on the regional network between December 1995 and May 2009 to calibrate the network Lg ‐wave magnitude. The calibrated network is used to calculate the Lg ‐wave body‐wave magnitude m b( Lg )=4.53 for the 25 May 2009 North Korean Nuclear explosion. Based upon 15 first arrivals from the two North Korea Nuclear explosions, the regional Pn velocity in the northeast China–North Korea region is calculated to be 8.0 km/s. This result, along with the regional geological structures, suggests that the North Korean Test site (NKTS) is located at a relatively stable continental region. We thus use a modified fully coupled magnitude–yield relation to estimate the explosion yield, and the result shows that the yield of the 25 May 2009 North Korean Nuclear Test is approximately 2.35 kt under the minimum burial depth assumption. Online Material: Epicentral parameters, computed m b( Lg ), and corrected m b( Lg ) for 82 events used in the study.
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regional seismic characteristics of the 9 october 2006 north korean Nuclear Test
Bulletin of the Seismological Society of America, 2008Co-Authors: Lianfeng Zhao, Xiaobi Xie, Weimin Wang, Zhenxing YaoAbstract:We investigate the regional seismic signature of the 9 October 2006 North Korean Nuclear Test. Broadband regional data for the Nuclear Test and a group of earthquakes close to the Test site were obtained between December 2000 and No- vember 2006. Epicentral distances from the stations to the Test site are between 371 and 1153 km. We first use these regional events to calibrate the Lg-wave magnitude in the network. Then the network is used to calculate mbLg �� 3:93 for the North Ko- rean Nuclear explosion. Using a modified fully coupled magnitude-yield relation, the yield of the North Korean Nuclear Test is estimated to be 0.48 kt. Because of large uncertainties in the source depth, the estimate is preliminary. The P=S-type spectral ratios Pg=Lg, Pn=Lg, and Pn=Sn are calculated for the Nuclear explosion and a group of earthquakes close to the Test site. At frequencies above 2 Hz, the network-averaged P=S spectral ratios clearly separate the 9 October 2006 explosion from the regional earthquakes. Our result indicates that a single-blast explosion in the North Korea re- gion shows different seismic characteristics from an earthquake. Any well-coupled single-blast explosion detonated in this region with yield similar to that for the North Korean Nuclear Test has a large probability of being identified by a regional seismic network such as the one adopted in this study.
Lianxing Wen - One of the best experts on this subject based on the ideXlab platform.
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seismological evidence for a low yield Nuclear Test on 12 may 2010 in north korea
Seismological Research Letters, 2015Co-Authors: Miao Zhang, Lianxing WenAbstract:Online Material: Location uncertainty estimation; figures of waveform comparison, location maps, and Pg / Lg spectral ratios; tables of earthquake parameters and Lg ‐wave amplitude ratios. Three Nuclear Tests (in 2006, 2009, and 2013) conducted by the Democratic People’s Republic of Korea (North Korea) are all detected and confirmed by many governmental and international agencies (e.g., the U. S. Geological Survey [USGS] and the Comprehensive Nuclear‐Test‐Ban Treaty Organization [CTBTO]). The locations and yields of these Tests have also been extensively studied by many research groups (e.g., Richards and Kim, 2007; Koper et al. , 2008; Zhao et al. , 2008, 2012, 2014; Murphy et al. , 2010; Wen and Long, 2010; Chun et al. , 2011; Zhang and Wen, 2013). However, it is under intensive debate among the governmental agencies and research groups whether North Korea has conducted other small Nuclear Tests. In particular, De Geer (2012) reported the detection of xenon and xenon daughter radionuclides between 13 and 23 May 2010 in four atmospheric radionuclide surveillance stations, located in South Korea, Japan, and the Russian Federation. He suggested the presence of barium‐140 can be explained only by a sudden Nuclear event, with the corresponding trinitrotoluene equivalent in a range of 50–200 t and the estimated time‐zero at 6:00+18 hr/−30 hr UTC on 11 May 2010 (De Geer, 2012; see also Brumfiel, 2012). The fissile material of the possible mid‐May 2010 Nuclear Test is indicated as uranium‐235 rather than the plutonium‐239 inferred from the radioxenon signal detected at Geojin in South Korea (De Geer, 2012, 2013), although Wright (2013) suggested they cannot be clearly discriminated …
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high precision location and yield of north korea s 2013 Nuclear Test
Geophysical Research Letters, 2013Co-Authors: Miao Zhang, Lianxing WenAbstract:[1] Using North Korea's 2009 Nuclear Test as reference and satellite imagery, we show that the location and yield of North Korea's 2013 Nuclear Test can be quickly and accurately determined based on seismic data. North Korea's 2013 Nuclear Test site is pinpointed by deriving relative location of North Korea's 2009 and 2013 Nuclear Tests and using the previously determined location of the 2009 Nuclear Test, while its yield is estimated based on the relative amplitude ratios of the Lg waves recorded for both events, the previously determined Lg-magnitude of 2009 Nuclear Test and burial depth inferred from satellite imagery. North Korea's 2013 Test site is determined to be located at (41°17′26.88″N, 129°4′34.68″E), about 345 m south and 453 m west of its 2009 Nuclear Test site, with a geographic precision of 94 m. Its yield is estimated to be 12.2 ± 3.8 kt.
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high precision location of north korea s 2009 Nuclear Test
Seismological Research Letters, 2010Co-Authors: Lianxing Wen, Hui LongAbstract:On 25 May 2009, the Democratic People's Republic of Korea (North Korea) announced that it had conducted a second Nuclear Test, without providing information of exact time, location, and yield. On that day, the United States Geological Survey (USGS) reported detecting a magnitude 4.7 seismic tremor in an aseismic region in North Korea (http://earthquake.usgs.gov/eqcenter/recenteqsww/Quakes/us2009hbaf.php; also archived copy at http://geophysics.geo.sunysb.edu/wen/NK/usgs\_north\_korea\_2009\_Test.webarchive). The seismic waveform features recorded at the seismic stations around the globe for the event exhibit characteristics of an explosion. However, the exact location of the Test remains elusive. Seismic monitoring of underground Nuclear explosions relies on seismic observations recorded by seismometers around the globe. Because seismic observations are influenced by the seismic properties along the paths of the wave propagation from the source to the seismometers, the accuracy of determination of an event location and time depends on the degree of our knowledge of the seismic properties in the interior of the Earth. The challenge in accurately determining the location of North Korea's Nuclear Tests stems from the fact that, due to the lack of seismic stations and seismicity in the region, the seismic structure is not known in enough detail that its influence can be well calibrated. For example, the horizontal uncertainty of the 2009 event location reported by the USGS is about ±3.8 km (http://earthquake.usgs.gov/eqcenter/recenteqsww/Quakes/us2009hbaf.php). While our knowledge of the seismic structure in the region is unlikely to improve soon, in this study we demonstrate a strategy that uses the forensic evidence registered by North Korea's 2006 Nuclear Test to determine the location of the 2009 Test in high precision, and we present our determination of the location of the 2009 Test. ### Scientific Evidence Registered by the 2006 Test The possible location of North Korea's 2006 Test is identified by satellite images (http://cryptome.org/eyeball/dprk-Test/dprkTest.htm; also an archived copy at http://geophysics.geo.sunysb.edu/wen/NK/eyeball.webarchive) (Table 1). High-quality …
Xiaobi Xie - One of the best experts on this subject based on the ideXlab platform.
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the 9 september 2016 north korean underground Nuclear Test
Bulletin of the Seismological Society of America, 2017Co-Authors: Lianfeng Zhao, Xiaobi Xie, Weimin Wang, Na Fan, Xu Zhao, Zhenxing YaoAbstract:We characterize the seismic events that occurred in North Korea on 9 September 2016 and South Korea on 12 September 2016. The 9 September 2016 event was identified as an explosion, and the two 12 September 2016 events were identified as natural earthquakes using the P/S (P-and S-wave) spectral ratios, Pg/Lg, Pn/Lg, and Pn/Sn as discriminants. The explosive event was relocated within the North Korean Nuclear Test site using a relative location method and the 2006 North Korea underground Nuclear Test as the master event, and the epicenter was identified at 41.2976 degrees N latitude and 129.0804 degrees E longitude. From the regional Lg and Rayleigh waves, the body-and surface-wave magnitudes for the 9 September 2016 event were calculated as m(b) (Lg) = 4: 8 +/- 0: 2 and M-s = 4: 2 +/- 0: 1. By adopting an empirical magnitude-yield relation for the body-wave magnitude, and assuming that the explosion was fully coupled and detonated at a normally scaled depth, we estimated that the seismic yield was similar to 6 kt, and the uncertainty range was between 3 and 11 kt. If an overburied depth range between 780 and 1200 m was applied, then the yield would be increased to 16-22 kt.
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the 12 february 2013 north korean underground Nuclear Test
Seismological Research Letters, 2014Co-Authors: Lianfeng Zhao, Xiaobi Xie, Weimin Wang, Zhenxing YaoAbstract:Online Material: Figures of Pn waveform comparisons and spectral ratios; tables of Pn differential times and parameters for events used in the study. On 12 February 2013, North Korea conducted its third and the largest Nuclear Test to date in the China–North Korea border area. According to local news, people living in nearby Chinese cities experienced shaking from this explosion. The U.S. Geological Survey (USGS) reported the explosion was located at (41.301° N, 129.066° E) and the magnitude was M 5.1. This event trigged abundant regional seismic phases in northeast China, Korea, and Japan. Because of its large magnitude, the seismic records from this event showed better signal‐to‐noise ratios than those from previous two Nuclear explosions. Illustrated in Figure 1 are broadband regional seismograms at station MDJ for three North Korea Nuclear Tests. These waveforms are highly similar, all are featured with abrupt P ‐wave arrivals, weak Lg phases and well‐developed short‐period Rayleigh waves. We collect the regional waveforms recorded on China National Digital Seismic Network (CNDSN), Global Seismic Network (GSN), and Japan F‐net to investigate the 12 February 2013 North Korean Nuclear Test. Figure 1. Seismograms recorded on MDJ from three North Korean Nuclear Tests in 2013, 2009, and 2006. Illustrated are normalized vertical displacements. The event date, maximum amplitudes, and epicenter distances are listed on the left. Marks on the waveforms indicate apparent group velocities. Note that the waveforms show similar features and display clear impulsive P ‐wave onset, relatively weak Lg phases, and 3–5 s period Rayleigh waves. ### High‐Precision Location By adopting the relative location method (e.g., Schaff and Richards, 2004; Zhang et al. , 2005; Wen and Long, 2010; Murphy et al. , 2013), and using the first North Korean Nuclear Test on 9 October 2006 as the master event, we calculate the origin times and locations of the 25 May 2009 and …
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regional seismic characteristics of the 9 october 2006 north korean Nuclear Test
Bulletin of the Seismological Society of America, 2008Co-Authors: Lianfeng Zhao, Xiaobi Xie, Weimin Wang, Zhenxing YaoAbstract:We investigate the regional seismic signature of the 9 October 2006 North Korean Nuclear Test. Broadband regional data for the Nuclear Test and a group of earthquakes close to the Test site were obtained between December 2000 and No- vember 2006. Epicentral distances from the stations to the Test site are between 371 and 1153 km. We first use these regional events to calibrate the Lg-wave magnitude in the network. Then the network is used to calculate mbLg �� 3:93 for the North Ko- rean Nuclear explosion. Using a modified fully coupled magnitude-yield relation, the yield of the North Korean Nuclear Test is estimated to be 0.48 kt. Because of large uncertainties in the source depth, the estimate is preliminary. The P=S-type spectral ratios Pg=Lg, Pn=Lg, and Pn=Sn are calculated for the Nuclear explosion and a group of earthquakes close to the Test site. At frequencies above 2 Hz, the network-averaged P=S spectral ratios clearly separate the 9 October 2006 explosion from the regional earthquakes. Our result indicates that a single-blast explosion in the North Korea re- gion shows different seismic characteristics from an earthquake. Any well-coupled single-blast explosion detonated in this region with yield similar to that for the North Korean Nuclear Test has a large probability of being identified by a regional seismic network such as the one adopted in this study.
