Relative Locations of the October 2006 and May 2009 DPRK Announced Nuclear Tests Using International Monitoring System Seismometer Arrays

Selby, Neil D.

doi:10.1785/0120100006

Cited by 32 publications

(42 citation statements)

References 14 publications

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“…Using a 1-dimensional global velocity model, the distances between the events estimated using teleseismic P phases are found to be approximately 25% shorter than the distances between events estimated using regional Pn phases. The 2009The , 2013, and 2016 events all take place within 1 km of each other and the discrepancy between the regional and teleseismic relative location estimates is no more than about 150 m. The discrepancy is much more significant when estimating the location of the more distant 2006 event relative to the later explosions with regional and teleseismic estimates varying by many hundreds of meters. The relative location of the 2006 event is challenging given the smaller number of observing stations, the lower signal-to-noise ratio, and significant waveform dissimilarity at some regional 2 S. J. Gibbons et al…”

Section: Discussionmentioning

confidence: 95%

“…test is significant for the problem of discerning the shape of the signal and the time of maximum correlation may have a significant error. The stacking of single-channel correlations (Gibbons & Ringdal 2006) was confirmed by Selby (2010) to give a more accurate time-delay measurement than a correlation of stack-and-delayed channels. The frequency of the teleseismic signal is significantly lower than for the regional signals displayed in the other three panels.…”

Section: Issues In Seismic Relative Event Locationmentioning

confidence: 90%

“…The two studies used mutually exclusive sets of observations with Wen & Long (2010) exploiting only regional Pn phases (observed on stations at distances within 1500 km of the source) and Selby (2010) exploiting only teleseismic P (observed at several thousand km). The two results are qualitatively identical with Selby (2010) pointing out that the regional estimate of Wen & Long (2010) falls within the uncertainty ellipse associated with the teleseismic estimate. However, with the goal of placing the events within the terrain and relative to the test-site infrastructure, the quantitative differences between the two studies are significant with the distance between the two events estimated around 25% further apart when the regional phases are used.…”

Section: Introductionmentioning

confidence: 99%

“…However, with the goal of placing the events within the terrain and relative to the test-site infrastructure, the quantitative differences between the two studies are significant with the distance between the two events estimated around 25% further apart when the regional phases are used. As Selby (2010) points out, the accuracy of measurement is a significant factor. (Measuring the time-delays from array-stacks of correlation functions rather than on single-trace correlation functions was demonstrated to result in a quantifiable reduction in the uncertainty ellipse.)…”

Section: Introductionmentioning

confidence: 99%

“…Fig. 1 shows the geometries of the networks used by Wen & Long (2010) and Selby (2010) together with calculations of the location of the 2006 event relative to the 2009 event using the time measurements provided in these publications. The estimates displayed in panels (b) and (d) of Fig.…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

Accurate relative location estimates for the North Korean nuclear tests using empirical slowness corrections

Gibbons¹,

Pabian

Näsholm³

et al. 2016

Geophys. J. Int.

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SUMMARYDeclared North Korean nuclear tests in 2006, 2009, 2013, and 2016 were observed seismically at regional and teleseismic distances. Waveform similarity allows the events to be located relatively with far greater accuracy than the absolute locations can be determined from seismic data alone. There is now significant redundancy in the data given the large number of regional and teleseismic stations that have recorded multiple events, and relative location estimates can be confirmed independently by performing calculations on many mutually exclusive sets of measurements. Using a 1-dimensional global velocity model, the distances between the events estimated using teleseismic P phases are found to be approximately 25% shorter than the distances between events estimated using regional Pn phases. The 2009The , 2013, and 2016 events all take place within 1 km of each other and the discrepancy between the regional and teleseismic relative location estimates is no more than about 150 m. The discrepancy is much more significant when estimating the location of the more distant 2006 event relative to the later explosions with regional and teleseismic estimates varying by many hundreds of meters. The relative location of the 2006 event is challenging given the smaller number of observing stations, the lower signal-to-noise ratio, and significant waveform dissimilarity at some regional 2 S. J. Gibbons et al.stations. The 2006 event is however highly significant in constraining the absolute locations in the terrain at the Punggye-ri test-site in relation to observed surface infrastructure.For each seismic arrival used to estimate the relative locations, we define a slowness scaling factor which multiplies the gradient of seismic traveltime versus distance, evaluated at the source, relative to the applied 1-d velocity model. A procedure for estimating correction terms which reduce the double-difference time residual vector norms is presented together with a discussion of the associated uncertainty. The modified velocity gradients reduce the residuals, the relative location uncertainties, and the sensitivity to the combination of stations used. The traveltime gradients appear to be overestimated for the regional phases, and teleseismic relative location estimates are likely to be more accurate despite an apparent lower precision. Calibrations for regional phases are essential given that smaller magnitude events are likely not to be recorded teleseismically. We discuss

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Section: Discussionmentioning

confidence: 95%

Section: Issues In Seismic Relative Event Locationmentioning

confidence: 90%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Accurate relative location estimates for the North Korean nuclear tests using empirical slowness corrections

Gibbons¹,

Pabian

Näsholm³

et al. 2016

Geophys. J. Int.

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On the infrasound detected from the 2013 and 2016 DPRK's underground nuclear tests

Assink

Averbuch

Smets

et al. 2016

Geophysical Research Letters

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The underground nuclear tests by the Democratic People's Republic of Korea (DPRK) generated atmospheric infrasound both in 2013 and 2016. Clear detections were made in the Russian Federation (I45RU) and Japan (I30JP) in 2013 at stations from the International Monitoring System. Both tropospheric and stratospheric refractions arrived at the stations. In 2016, only a weak return was potentially observed at I45RU. Data analysis and propagation modeling show that the noise level at the stations and the stratospheric circumpolar vortex were different in 2016 compared to 2013. As the seismic magnitude of the 2013 and 2016 nuclear test explosions was comparable, we hypothesize that the 2016 test occurred at least 1.5 times deeper. In such a case, less seismic energy would couple through the lithosphere‐atmosphere interface, leading to less observable infrasound. Since explosion depth is difficult to estimate from seismic data alone, this motivates a synergy between seismics and infrasonics.

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Relative surface wave amplitude and phase anomalies from the Democratic People's Republic of Korea announced nuclear tests

Ichinose

Myers

Ford

et al. 2017

Geophysical Research Letters

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We performed relative locations of six event pairs based on surface wave (SW) and body wave (BW) differential traveltimes of the 9 September 2016, 6 January 2016, 12 February 2013, and 25 May 2009 announced North Korea nuclear explosions. The SW relative locations for the 25 May 2009 and 12 February 2013 events were inconsistent with the BWs when paired with other events, and only the 6 January 2016/9 September 2016 pair was consistent. Apparent SW phase shift is investigated with respect to the BW relative locations. The pairs formed with the 25 May 2009 and 12 February 2013 events, beneath the southeast slope of Mount Mant'ap, have the largest phase shifts and amplitude ratio deviations, whereas the least deviation was from the 6 January 2016 and 9 September 2016 event pair beneath the mountain peak. Regional moment tensors (MTs) predict the amplitude ratios but do not resolve the relative phase. We find that MTs with 10% difference in isotropic and rotated +CLVD can fit both relative phase and amplitude ratios. SW relative locations of highly isotropic and correlated explosion clusters can be affected by topography and small differences in MT.

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Relative Locations of the October 2006 and May 2009 DPRK Announced Nuclear Tests Using International Monitoring System Seismometer Arrays

Cited by 32 publications

References 14 publications

Accurate relative location estimates for the North Korean nuclear tests using empirical slowness corrections

Accurate relative location estimates for the North Korean nuclear tests using empirical slowness corrections

On the infrasound detected from the 2013 and 2016 DPRK's underground nuclear tests

Relative surface wave amplitude and phase anomalies from the Democratic People's Republic of Korea announced nuclear tests

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