The North conducted two nuclear tests a year ago alone.
The blast first measured in at 5.6 on the Richter scale but has since been revised up to a much stronger 6.3.
The Chinese Earthquake Networks Center, or CENC, reported that a second tremor measuring 4.6 occurred minutes after the first, noting that it might be a "collapse earthquake", according to China's Xinhua news agency.
Pyongyang claimed leader Kim Jong-un had inspected a hydrogen bomb meant for a new intercontinental ballistic missile hours before the tremors were felt. However, the said picture couldn't be verified independently and no journalists were present when the photo was taken.
South Korea has refuted a news report that there was a second natural disaster near North Korea's nuclear test site.
South Korea's Yonhap news service reported a second quake had happened eight minutes after the first, citing China's natural disaster agency.
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The second natural disaster occurred around one kilometer northwest from the location North Korea appears to have conducted its sixth nuclear test, the USGS data shows.
It said the test was conducted according to the plans of the North's ruling Workers' Party to establish the nation as a nuclear power.
Tensions flared up between the US and the North after the ICBM tests with US President Donald Trump earlier warning of "fire and fury" against the North.
North Korean leader Kim Jong Un inspects missiles.
China is by far the North's biggest trading partner, but Mr Trump appeared to be more critical of South Korean President Moon Jae-in, who has attempted to reach out to the North.
In January 2016, North Korea conducted its fourth nuclear test, which Pyongyang claimed to be a test of a hydrogen bomb.
A 6.3-magnitude tremor, according to USA and Chinese government seismologists, was recorded at surface level, centered at Punggye-ri where North Korea's nuclear test facility is located. "That scale is to the level where anyone can say a hydrogen bomb test". "The North Koreans have said this was a goal for a long time".
The KCNA report made no mention of plans for a sixth nuclear test. It last detonated a nuclear device on September 9 - its foundation day - previous year.
If the current magnitude holds, it's possible that the weapon tested Sunday was a thermonuclear device, but it's impossible to say if it was the peanut-shaped object shown in the images released by North Korean state media, says Hanham.