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Abstract <p>Between January and March 2022, fifteen shallow seismic events occurred near the Punggye-ri Nuclear Test Site in North Korea. These events raised concerns about their source nature, particularly in light of satellite observations suggesting renewed activity at the site. Here, we analyzed vertical-component seismograms recorded at 38 broadband stations with epicentral distances ranging from 70 to 600&#xa0;km. Regional phases, Pn, Pg, Sn, and Lg, were used to calculate P/S spectral amplitude ratios. The network-averaged P/S-type spectral ratios were computed at a reference distance of 300&#xa0;km to distinguish potential explosions from natural tectonic earthquakes. The spectral-ratio characteristics of all 15 shallow events closely align with those of tectonic earthquakes. The shallow events can be clearly separated from the underground-explosion population. Therefore, the 15 seismic events are likely to be natural tectonic earthquakes resulting from local stress imbalances.</p> Highlights <p>• Multi-station P/S spectral ratios were used to identify 15 small-magnitude events near the North Korean nuclear test site.</p> <p>• The seismic events are characterized by tectonic earthquakes, which are discriminated from historical underground nuclear tests.</p>

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Discrimination of seismic event near the North Korean nuclear test site (January-March 2022) using multi-station P/S spectral ratios

  • 期刊论文

  • 发表日期：

    2026年1月17日

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  • Bo-Han Wang,
  • Lian-Feng Zhao,
  • Xiao-Bi Xie,
  • Xi He,
  • Yong Zhao,
  • Zhen-Xing Yao

摘要

Abstract

Between January and March 2022, fifteen shallow seismic events occurred near the Punggye-ri Nuclear Test Site in North Korea. These events raised concerns about their source nature, particularly in light of satellite observations suggesting renewed activity at the site. Here, we analyzed vertical-component seismograms recorded at 38 broadband stations with epicentral distances ranging from 70 to 600 km. Regional phases, Pn, Pg, Sn, and Lg, were used to calculate P/S spectral amplitude ratios. The network-averaged P/S-type spectral ratios were computed at a reference distance of 300 km to distinguish potential explosions from natural tectonic earthquakes. The spectral-ratio characteristics of all 15 shallow events closely align with those of tectonic earthquakes. The shallow events can be clearly separated from the underground-explosion population. Therefore, the 15 seismic events are likely to be natural tectonic earthquakes resulting from local stress imbalances.

Highlights

• Multi-station P/S spectral ratios were used to identify 15 small-magnitude events near the North Korean nuclear test site.

• The seismic events are characterized by tectonic earthquakes, which are discriminated from historical underground nuclear tests.