Aftershock Emission at the DPRK Punggye-ri Test Site Continues to the Present

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 aftershock emissions differ significantly from the known estimates obtained previously after numerous underground explosions in various seismotectonic settings. Specifically, a continuous sequence of seismic events after the sixth explosion announced in 2017 has been observed for more than seven 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 known Omori law. The number of events with relatively high magnitudes is increasing. The uniqueness of the aftershock sequence requires high sensitivity of the recording system and resolution of signal detection methods, as well as accurate estimation of the source parameters for further study of the nature and mechanisms of postseismic activity.