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

Abstract

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.

Infrasound and seismoacoustic signatures of the 28 September 2018 Sulawesi super-shear earthquake

“…This will also help to optimize seismoacoustic observation networks in terms of better understanding instrumental needs and better evaluating the signatures observable by them. Finally it will support seismoacoustic studies of natural as well as anthropogenic infrasound sources in the future and thereby support the infrasound monitoring for treaty verification purposes of the CTBT, as have other CTBT-related studies about infrasound observation, propagation, and signal characterization (Assink et al, 2016;Bowman, 2019;Gaebler et al, 2019).…”

“…Most of the acoustic energy is concentrated at the low-frequency band of 0.2 Hz. This was calculated applying the Infrasonic Energy, Nth Octave (IN-FERNO) algorithm (see Garcés, 2013) to the station data. It calculates acoustic energy with frequency bands based on the American National Standards Institute (ANSI) and International Organization for Standardization (ISO) standards for noise characterization for the acoustic range extended into the infrasound range, and it is based on fractional octave bands.…”

“…The main focus of the discussion of observed and modeled signals from the 28 September 2018 Sulawesi earthquake is on the source regions and source mechanisms responsible for them. To support this discussion, a back-projection procedure (comparable to the one applied in Shani-Kadmiel et al, 2017, and in the Supplement to Gaebler et al, 2019) is applied using the observed PMCC pixels and back-projecting them using their temporal and directional information.…”

“…Signals are identified as pixel information in distinct time steps and frequency bands, and they are clustered to signal families related to the same event. The 1/3 octave band configurations with an inversefrequency-distributed window length are implemented between 0.01 and 4.4 Hz (Garcés, 2013). Signals can be associated with a certain source by, e.g., applying cross-bearing techniques on the back-azimuth directions of two or more arrays (Matoza et al, 2017).…”

Časová rezidua odečtů P vln ze severokorejské jaderné exploze z roku 2017 a jejich příspěvek k problematice nehomogenit litosféry ve střední Evropě

“…snímcích. Výsledky studia povrchových deformací na základě satelitních snímků ukazují, že skutečné epicentrum mohlo být pouze přibližně dva kilometry od pozemních objektů jaderné střelnice (Wang et al 2018;Gaebler et al 2019). Nejistota v určení epicentra exploze se tedy pohybuje řádově v jednotkách kilometrů, odchylka lokace vypočítané na ÚFZ v Brně od ostatních řešení je menší než pět kilometrů.…”