North Korea's 2017 Test and its Nontectonic Aftershock

Liu, J.; Li, L.; Zahradnı́k, Jiřı́; Sokos, Efthimios; Liu, C.; Tian, Xiaobin

doi:10.1002/2018gl077095

Cited by 38 publications

(20 citation statements)

References 35 publications

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“…3D and fig. S16) shows very high waveform crosscorrelation coefficients, even for some coda waves, supporting the close locations but opposite isotropic polarities of the two events (2).…”

Section: Research | Reportmentioning

confidence: 60%

The rise, collapse, and compaction of Mt. Mantap from the 3 September 2017 North Korean nuclear test

Wang

Shi

Nikkhoo

et al. 2018

Science

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Surveillance of clandestine nuclear tests relies on a global seismic network, but the potential of spaceborne monitoring has been underexploited. We used satellite radar imagery to determine the complete surface displacement field of up to 3.5 meters of divergent horizontal motion with 0.5 meters of subsidence associated with North Korea's largest underground nuclear test. Combining insight from geodetic and seismological remote sensing, we found that the aftermath of the initial explosive deformation involved subsidence associated with subsurface collapse and aseismic compaction of the damaged rocks of the test site. The explosive yield from the nuclear detonation with best-fitting source parameters for 450-meter depth was 191 kilotonnes of TNT equivalent. Our results demonstrate the capability of spaceborne remote sensing to help characterize large underground nuclear tests.

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“…3D and fig. S16) shows very high waveform crosscorrelation coefficients, even for some coda waves, supporting the close locations but opposite isotropic polarities of the two events (2).…”

Section: Research | Reportmentioning

confidence: 60%

The rise, collapse, and compaction of Mt. Mantap from the 3 September 2017 North Korean nuclear test

Wang

Shi

Nikkhoo

et al. 2018

Science

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“…The method of change detection analysis based on the Normalized Differential Vegetation Index (NDVI) is applied. Spaceborne InSAR has been used to detect surface displacements of the Earth's surface for more than 20 years (Massonnet et al, 1993) and has reached maturity in recent years (Adam et al, 2009), nowadays allowing for the detection of surface displacements with a precision on the order of a few millimeters. Repeat pass interferometry is based on the registered interferometric phase per ground cell (pixel) and is related to the distance differences between the scatterer and the synthetic aperture radar (SAR) sensor between two acquisitions separated in time.…”

Section: Remote-sensing Studiesmentioning

confidence: 99%

A multi-technology analysis of the 2017 North Korean nuclear test

et al. 2019

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Abstract. On 3 September 2017 official channels of the Democratic People's Republic of Korea announced the successful test of a thermonuclear device. Only seconds to minutes after the alleged nuclear explosion at the Punggye-ri nuclear test site in the mountainous region in the country's northeast at 03:30:02 (UTC), hundreds of seismic stations distributed all around the globe picked up strong and distinct signals associated with an explosion. Different seismological agencies reported body wave magnitudes of well above 6.0, consequently estimating the explosive yield of the device on the order of hundreds of kT TNT equivalent. The 2017 event can therefore be assessed as being multiple times larger in energy than the two preceding North Korean events in January and September 2016. This study provides a multi-technology analysis of the 2017 North Korean event and its aftermath using a wide array of geophysical methods. Seismological investigations locate the event within the test site at a depth of approximately 0.6 km below the surface. The radiation and generation of P- and S-wave energy in the source region are significantly influenced by the topography of the Mt. Mantap massif. Inversions for the full moment tensor of the main event reveal a dominant isotropic component accompanied by significant amounts of double couple and compensated linear vector dipole terms, confirming the explosive character of the event. The analysis of the source mechanism of an aftershock that occurred around 8 min after the test in the direct vicinity suggest a cavity collapse. Measurements at seismic stations of the International Monitoring System result in a body wave magnitude of 6.2, which translates to an yield estimate of around 400 kT TNT equivalent. The explosive yield is possibly overestimated, since topography and depth phases both tend to enhance the peak amplitudes of teleseismic P waves. Interferometric synthetic aperture radar analysis using data from the ALOS-2 satellite reveal strong surface deformations in the epicenter region. Additional multispectral optical data from the Pleiades satellite show clear landslide activity at the test site. The strong surface deformations generated large acoustic pressure peaks, which were observed as infrasound signals with distinctive waveforms even at distances of 401 km. In the aftermath of the 2017 event, atmospheric traces of the fission product 133Xe were detected at various locations in the wider region. While for 133Xe measurements in September 2017, the Punggye-ri test site is disfavored as a source by means of atmospheric transport modeling, detections in October 2017 at the International Monitoring System station RN58 in Russia indicate a potential delayed leakage of 133Xe at the test site from the 2017 North Korean nuclear test.

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“…A variety of methods have been used to estimate the yields or seismic moments of the six tests, including assumed transportability of body wave, surface wave, or Lg magnitude yield scaling relations (e.g., Chun et al, ; Hartmann et al, ; Yao et al, ; Zhang & Wen, ; Zhao et al, , , , , Zhao, Xie, Wang, et al, ,Zhao, Xie, He, et al, ); modeling of surface deformation (Wang et al, ; Wei, ), regional waveforms and spectra (e.g., Murphy et al, ; Rougier et al, ; Stevens & O'Brien, ; Stroujkova, ; Wang et al, ), regional coda envelopes (e.g., Pasyanos & Myers, ), network‐averaged teleseismic P wave spectra (e.g., Murphy et al, ), and teleseismic P waveforms (e.g., Chaves et al, ; Ni et al, ); and moment tensor inversion for the total and isotropic moment of the explosions (e.g., Alvizuri & Tape, ; Barth, ; Cesca et al, ; Chiang et al, ; Ford et al, ; Ichinose et al, ; Liu, Li, Zahradnik, Sokos, Liu, et al, ,Liu, Li, Zahradník, Sokos, & Plicka, ; Vavrycuk & Kim, ; Wang et al, ; Yao et al, ). Some depth constraints are inferred from infrasound as well (Assink et al, ).…”

Section: Introductionmentioning

confidence: 99%

Yield Estimates for the Six North Korean Nuclear Tests From TeleseismicPWave Modeling and Intercorrelation ofPandPnRecordings

et al. 2019

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The yields of the six declared underground nuclear tests at the North Korean test site are estimated using high-frequency teleseismic P wave amplitude modeling and waveform equalization of short-period teleseismic P waves and regional Pn signals. Average amplitudes of the first cycle of high-frequency (>4 Hz) filtered P wave displacements for each event, adjusted for station sampling relative to the 3 September 2017 event, are modeled using Mueller-Murphy explosion source models for granite and a constant-Q attenuation operator with t* = 0.78 ± 0.03 s. The yield estimates range from 2.6 to 230 kt. Intercorrelation, a waveform equalization procedure that accounts for source function and depth-phase variations between events, is applied to large sets of filtered (>0.8 Hz) teleseismic P and regional Pn seismograms. Searching over yield and burial depth for both events gives optimal parameters by simultaneous waveform equalization of multiple stations. Using specified burial depths spanning from 430 to 710 m for all events based on estimated locations in the source topography assuming tunneling with 4% grade, along with allowing for reduction in source region velocity due to weathering, rock layering, and damage zones, gives yield estimates ranging from 1.4 to 250 kt. Comparison of predicted and observed spectral ratios of Pn phases at station MDJ establishes that these source models are reasonable. Using the preferred yield estimates from intercorrelation, W IC , a yield-calibrated relation of m bNEIC = 0.9 log 10 W IC + 4.13 is determined for the North Korean test site.

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North Korea's 2017 Test and its Nontectonic Aftershock

Cited by 38 publications

References 35 publications

The rise, collapse, and compaction of Mt. Mantap from the 3 September 2017 North Korean nuclear test

The rise, collapse, and compaction of Mt. Mantap from the 3 September 2017 North Korean nuclear test

A multi-technology analysis of the 2017 North Korean nuclear test

Yield Estimates for the Six North Korean Nuclear Tests From TeleseismicPWave Modeling and Intercorrelation ofPandPnRecordings

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