Overview
- An international team published a Science paper in mid-September 2026 that identified 1,399 local earthquakes near Punggye‑ri between 2008 and May 2025, with activity rising sharply after North Korea’s largest underground test in September 2017.
- The researchers used matched‑filter and multi‑station waveform analysis of seismic records from China and South Korea to detect small, shallow events that earlier catalogs missed, and they excluded signals seen at only one or two stations so the count is conservative.
- Most events were shallow and small at first (about M1–1.3) but grew into the M2–3 range by 2023–2025, with the largest around M3.4, and high‑precision locations show quakes concentrated along two roughly north‑northwest fault strands about 24 km long.
- The team concludes that repeated underground detonations likely fractured and weakened the near‑surface crust, progressively reactivating preexisting intraplate faults rather than producing only short‑lived aftershocks.
- The findings raise practical concerns: monitoring and test‑ban verification may need years‑to‑decades of continued surveillance to distinguish lingering, test‑related seismicity from natural quakes, and nearby communities face a changed local seismic hazard if faults continue to slip.