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

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Science  13 Jul 2018:
Vol. 361, Issue 6398, pp. 166-170
DOI: 10.1126/science.aar7230
  • Fig. 1 Three-dimensional displacement associated with the 3 September 2017 North Korea nuclear test (NKNT 6).

    (A) 3D displacements derived from radar imagery. Arrows indicate horizontal displacement; color indicates vertical motions spanning the explosion and ~1 week of additional deformation. The uncertainties are shown in fig. S4 and provided in data S1 with the displacements. The black outline derived from ALOS-2 coherence loss indicates the substantial surface disturbance and large displacement gradients caused by the explosion over an area of ~9 km2 (figs. S1 and S2). Thin gray lines are topographic contours at 100-m intervals. The red square in the upper right inset shows the location of Mount Mantap (DPRK, Democratic People’s Republic of Korea; ROK, Republic of Korea). Red stars indicate the locations of NKNT 1–5 (1, 6, 9, 15, 37), among which NKNT 2–5 were all located within the NKNT 6 low-coherence region; NKNT 1 on 9 October 2006 was in a different location (5). Beach balls show locations and focal mechanisms of the Mw 5.24 and Mw 4.47 events on 3 September 2017. (B and C) 2D (horizontal along the profile and vertical) displacements along two profiles across the top of Mount Mantap from north to south and from west to east, respectively. No vertical exaggeration in (B) or (C).

  • Fig. 2 Model geometry and fit to the observed surface displacements.

    (A) Perspective view of the model with topography and variance reductions as a function of centroid position (both cross sections are centered on the best-fit location). We represent the first event, combining the explosion and immediate collapse, using a sphere of 300 m radius with a centroid located at a depth about 450 m below Mount Mantap. We model the aseismic subsidence detected with geodetic data about a week after the seismic events 1 and 2 with an ellipsoid of dimension 800 m × 800 m × 470 m (semi-axes), centered at 100 m deeper than the explosive source. The isotropic components of the moment tensors are represented as beach balls. (B) The interferometric SAR (InSAR) observed and simulated surface displacements. (C) The west-east and south-north profiles of the surface displacements from the SAR observations and the best-fitting models. The dashed profiles represent the contributions of the explosion/collapse (event 1) and the subsequent aseismic compaction on the surface displacement. We ignore the deformation caused by event 2.

  • Fig. 3 Analysis of seismic waves.

    (A) Station map of broadband seismometers with four stations in (B) and (D) highlighted in red. The black and red stars are the epicenter locations of the first and second event, respectively. (B) Moment tensor solutions for the first explosive event (left) and the second implosive event (right), with the vertical component of two representative stations shown at the bottom. Both data and synthetics are filtered between 0.02 and 0.045 Hz. Station names are shown at the beginning of waveform pairs; distance (in kilometers) and azimuth (in degrees) are indicated below. (C) Grid search result (under L1 norm) for relocating the second event relative to the first event (black star). Marginal distributions for the epicentral position are plotted along the northing and easting axes. (D) Vertical component waveform comparison between the first (black) and the second (red) event at two representative stations, with the second event waveforms multiplied by –60. (E) Explosive yield in the context of historical nuclear tests. The black dots and error bars show yields estimated according to the mean and standard deviation of tabulated moment within 95% of the best-fitting solutions with depths of 300 m, 450 m, and 600 m, respectively.

  • Fig. 4 Summary deformation scenario for the 3 September 2017 North Korea nuclear test.

    (A, B, and D) The unfolding of events includes the succession of explosive (A), collapse (B), and compaction (D) processes, with different associated surface displacements. (C) The implosive source may be shallow and may only contribute localized surface displacements. The radar imagery reveals the deformation [arrows in (D)] resulting from the three processes.

Supplementary Materials

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

    Teng Wang, Qibin Shi, Mehdi Nikkhoo, Shengji Wei, Sylvain Barbot, Douglas Dreger, Roland Bürgmann, Mahdi Motagh, Qi-Fu Chen

    Materials/Methods, Supplementary Text, Tables, Figures, and/or References

    Download Supplement
    • Materials and Methods
    • Figs. S1 to S16
    • Tables S1 to S3
    • Captions for data S1 and S2
    • References

    Additional Data

    Data S1
    Data S2

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