The artificial quake was 9.8 times more powerful than after North Korea’s fifth nuclear test, according to Seoul’s weather agency.
It follows an announcemnt late on Saturday by North Korea that it had developed a more advanced nuclear weapon that has “great destructive power”.
Earlier North Korea’s state media said Kim Jong-un had supervised the loading of a hydrogen bomb into an intercontinental ballistic missile (ICBM) capable of reaching the US.
The 6.3 magnitude tremor was detected near North Korea’s Punggye-ri nuclear test facility.
More to follow…