Aftershock emission at the DPRK Punggye-ri test site is continuing

An unprecedented increase in postseismic activity at the Punggye-ri test site, DPRK, has been recorded by the International Monitoring System (IMS) stations over the past year and a half. The main parameters of the aftershock emission differ significantly from the well-known estimates made previously after numerous underground explosions in various seismotectonic settings. Essentially, a continuous sequence of seismic events after the sixth announced explosion in 2017 has been observed for more than 7 years. Since the second half of 2023, an increase in the frequency of seismic events has been recorded. Both observed processes are not consistent with the well-known Omori law. The number of events with relatively high magnitudes is increasing. The uniqueness of the aftershock sequence requires high sensitivity of the registration system and resolution of signal detection methods, as well as the accuracy of the source parameters for further study of the nature and mechanisms of postseismic activity.