The epicenter is roughly the same as that of a previous shallow earthquake on September 3, which turned out to be caused by a North Korean nuclear test, the official Xinhua news agency said.
The earthquake comes after days of increasingly bellicose rhetoric between US President Donald Trump and Kim Jong-Un’s regime, which has raised international alarm.
The September test was North Korea’s sixth and most powerful detonation, triggering a much stronger 6.3-magnitude quake that was felt across the border in China.
Pyongyang later said it had tested a hydrogen bomb that could be fitted onto a missile — an assertion that no foreign government has so far confirmed.
The move prompted global condemnation, leading the UN Security Council to unanimously adopt new sanctions that include restrictions on oil shipments.
Hydrogen bombs, or H-bombs, are thermonuclear weapons far more powerful than ordinary fission-based atomic bombs, and use a nuclear blast to generate the intense temperatures required for fusion to take place.