Seismic Spectral Ratios Between North Korean Nuclear Tests: Implications for Their Seismic Sources

Jin, Peiquan; Zhu, Hengshu; Xu, Xiong; Wang, P. Z.; Li, X.; Shen, Xu-feng

doi:10.1029/2018jb016554

Cited by 5 publications

(5 citation statements)

References 37 publications

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“…In this study we only consider the source parameters obtained from the intercorrelation results of Lay (2022), and the teleseismic P wave modeling results of Voytan et al (2019), since the intercorrelation results obtained by the method in both studies are in good agreement. Jin et al (2019) use spectral ratios of body-waves to fit physics-based source models to the five declared nuclear tests occurring between May 2009 and September 2017 (i.e., NK2-NK6). For these five events, high-quality waveforms with a broad frequency range of high SNR are available at regional and teleseismic distances.…”

Section: Previous Yield Estimatesmentioning

confidence: 99%

“…For these five events, high-quality waveforms with a broad frequency range of high SNR are available at regional and teleseismic distances. In order to avoid interference from depth phases (pP) which are present in the teleseismic source spectra, Jin et al (2019) use only the regional P wave spectral ratios model to invert for the yields and DoBs with the depth of NK6 fixed a priori. Zhao et al (2008Zhao et al ( , 2012Zhao et al ( , 2014 and Zhao, Xie, Wang et al (2017).…”

Section: Previous Yield Estimatesmentioning

confidence: 99%

“…In order to overcome the difficulties posed by estimating explosive yield from the the body‐wave magnitude without a calibrated magnitude‐yield relationship, different methods of fitting physically based source models which are not calibrated to a specific region to seismic observations have been used (e.g., Jin et al., 2019; Lay, 2022; Park et al., 2022; Pasyanos & Myers, 2018; Voytan et al., 2019). The most widely accepted model used to predict the spectra of nuclear explosions is the Mueller‐Murphy model (MM71; Mueller & Murphy, 1971), which parameterizes the seismic source coupling due to the source medium, yield ( W ) and depth of burial ( h ) of the explosion.…”

Section: Introductionmentioning

confidence: 99%

“…Jin et al. (2019) use spectral ratios of body‐waves to fit physics‐based source models to the five declared nuclear tests occurring between May 2009 and September 2017 (i.e., NK2–NK6). For these five events, high‐quality waveforms with a broad frequency range of high SNR are available at regional and teleseismic distances.…”

Section: Introductionmentioning

confidence: 99%

“…In order to avoid interference from depth phases ( pP ) which are present in the teleseismic source spectra, Jin et al. (2019) use only the regional P wave spectral ratios model to invert for the yields and DoBs with the depth of NK6 fixed a priori.…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

Source Characterization of the Declared North Korean Nuclear Tests From Regional Distance Coda Wave Spectral Ratios

et al. 2023

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Seismic observations of underground nuclear explosions provide crucial data on source yield and depth that cannot easily be estimated from other geophysical methods. However, it is difficult to obtain reliable yield estimates for test sites for which we do not have direct seismic calibration experiments. To obtain source information from uncalibrated sites and paths, local and regional seismic records of six, proximal, declared underground nuclear explosions in North Korea are used to compute spectral ratios of narrow‐band waveform envelopes of body‐wave coda that remove path and site effects to reveal precise, relative source moment. The yields of these explosions are obtained from the observed source ratios by simultaneously fitting the classical source model of Mueller and Murphy (1971), https://doi.org/10.1785/bssa0610061675 to all event pairs. The source model provides an impressive fit to the observations considering that the P phase coda derived source spectral ratios did not require a prior knowledge of the source or regionally calibrated corrections to be applied to the data. However, the observed corner frequencies from S wave coda spectral ratios are lower than the source model predictions, but are well fit by models calculated using the corner frequency consistent with the Fisk conjecture. The results presented here provide novel constraints on the spectral distributions of the energy radiated by the sources of the DPRK test series, and allows for an independent evaluation of existing estimated source model parameters.

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Section: Previous Yield Estimatesmentioning

confidence: 99%

Section: Previous Yield Estimatesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Source Characterization of the Declared North Korean Nuclear Tests From Regional Distance Coda Wave Spectral Ratios

et al. 2023

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On the seismic source function of an underwater explosion

Jin

Wang

et al. 2022

Geophysical Journal International

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Summary The seismic source function of an underwater explosion (UWE) is studied based on characteristics of the shock wave and the secondary bubble pulses. A mathematic representation for the full pressure history including overpressure and underpressure caused by both shock wave and bubble pulses is presented. Based on the full pressure model, UWEs’ reduced displacement/velocity potentials both in time and frequency domain are obtained. The new seismic source model overcomes the theoretical inconsistency with the UWE seismic source model presented by Savage & Helmberger (2001) taking account of the shock wave overpressure only, and the steady- state reduced displacement potential predicted by the full pressure model is much larger than that predicted by the shock wave model by a factor that would exceed 100 for shallow underwater explosions. Relative seismic effect between underwater and underground explosions is modeled and the result by the full pressure model is consistent with observations that seismic magnitude of an UWE commonly is much larger than magnitude of an underground explosion of the same yield. And to further validate the full pressure model, Pn spectra of a 10,000lbs UWE off the east coast of Florida detonated on June 10, 2016 are modeled for six regional stations, and the results predicted by the full pressure model agree well with corresponding observations.

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Source Spectra of Pg and Lg Waves from North Korean Nuclear Tests Estimated Using a Nonmodel-Based Approach

Jin,

Xu,

Ding

et al. 2023

Bulletin of the Seismological Society of America

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In this article, we demonstrate that source spectra for regional seismic waves generated by an underground explosion may be uniquely extracted using a simple linear regression method between the geometrical spreading corrected displacement spectra and epicentral distances as long as the recording stations are well distributed in distances. Using this method, source spectra of Pg and Lg waves from North Korean nuclear tests conducted between 2009 and 2017 are estimated, respectively, and are compared to test the conjecture of Fisk (2006) as well as to determine the relative size between the seismic moment of Lg waves and that of compressional waves. For a specified explosion, the resultant Pg and Lg source spectra approximately have equal low-frequency source level. Based on this result, it is estimated that for the explosions seismic moment of Lg waves would be about 35% of that of compressional waves. In addition, it is shown the Fisk conjecture approximately stands, as for a specified explosion the observed Pg and Lg source spectra share the same manner of high-frequency rolloff as f−2, the source corner frequency of Lg waves is smaller than that of Pg waves by a factor of about 1/3, and the Pg source spectrum exhibits a prominent overshoot, whereas it is not obvious in corresponding Lg source spectrum. The new method for source spectra estimation may have a promising application prospect in monitoring studies. As an example, it is shown that the yield and even buried depths of the North Korean nuclear explosions may be reasonably estimated by fitting the observed Pg source spectra using an MM71- (Mueller and Murphy, 1971) and DJ91 (Denny and Johnson, 1991)-based hybrid source model suggested by Ford and Walter (2013).

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Seismic Spectral Ratios Between North Korean Nuclear Tests: Implications for Their Seismic Sources

Cited by 5 publications

References 37 publications

Source Characterization of the Declared North Korean Nuclear Tests From Regional Distance Coda Wave Spectral Ratios

Source Characterization of the Declared North Korean Nuclear Tests From Regional Distance Coda Wave Spectral Ratios

On the seismic source function of an underwater explosion

Source Spectra of Pg and Lg Waves from North Korean Nuclear Tests Estimated Using a Nonmodel-Based Approach

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