The Comprehensive Test Ban Treaty Organisation (CTBTO) said the tremors were unlikely to have been man-made, following initial concerns Pyongyang had carried out further weapons tests.
An quake measuring 3.4 magnitude on the richter scale was detected in North Korea, claimed China's Xinhua news agency.
There has been name-calling and heightened tensions between Washington and Pyongyang this week as the United Nations met in NY.
However, South Korea's weather agency was viewing the earthquake as a natural phenomenon and said they are still examining the reasons for the quake.
USGS put the epicentre of the quake 22 km (14 miles) east-northeast of Sungjibaegam, North Korea, near the country's main nuclear test site.
President Donald Trump, while issuing another sabre-rattling remark against Jong-un, called him a "madman" who will starve his populace to built weapons.
China will suspend such exports once the total exports approaches the ceiling.
Saturday's seismic activity came just hours before North Korea's Foreign Minister Ri Yong Ho - who warned on Thursday that North Korea could consider a hydrogen bomb test of an unprecedented scale over the Pacific - was due to address the United Nations General Assembly in NY.
A USA government intelligence analyst said the events could have been a "mine-type" collapse of tunnels damaged by North Korea's previous nuclear test, but was more likely a small natural disaster.
The South Korean agency confirmed there were two earthquakes Saturday. North Korea relies heavily on textiles, it's one last major source of foreign revenue.
In a rare direct statement, Kim said that Trump would "pay dearly" for the threats, and that North Korea "will consider with seriousness exercising of a corresponding, highest level of hard-line countermeasure in history". In response, the United Nations passed a range of new sanctions against North Korea, including petroleum and textiles restrictions.
The site, run by the U.S. -Korea Institute at Johns Hopkins University's School of Advanced International Studies, added the bomb's 250-kiloton yield was close to what it previously determined was the maximum that could be contained by the test site.