The move came in response to North Korea's missile launches in July, which it, as well as South Korea and the USA, claimed were intercontinental ballistic missile (ICBM) tests.
South Korea's Meteorological Administration called it a "man-made" natural disaster.
United States Geological Survey recorded the magnitude at 6.3 - larger than any previous test. North Korea last tested a nuclear device about a year ago.
North Korea has appeared to have conducted a sixth nuclear test.
North Korea past year conducted its fourth and fifth nuclear tests, saying the fourth in January 2016 was a successful hydrogen bomb test, although outside experts say the claim has not been proven.
The apparent test came just hours after it claimed to have developed a hydrogen bomb that could be loaded into the country's new intercontinental ballistic missile.
"Kim Jong-un is playing a game of very, very risky brinkmanship", Turnbull said, referring to North Korea's dictator.
CNN reports that the United States and South Korea carried out a joint exercise in the form of a mock bombing to simulate recreate a strike on enemy facilities.
South Korean and Japanese jets joined exercises with two supersonic U.S. B-1B bombers above and near the Korean peninsula on Thursday, two days after North Korea sharply raised tension by firing a missile over Japan.
Trump Reportedly Circumvents Kelly By Calling Friends On Personal Cell Phone
With Schiller gone, the number of original Trumpers left will be awfully small, just Hope Hicks, Dan Scavino, and the children. Kelly is looking to "put a dent" in Omarosa's influence and has been limiting her access to the president.
China has expressed annoyance at North Korea's frequent ballistic missile launches, but analysts have said China probably would not take serious action - unless there is another nuclear test.
However, Trump said after the latest missile test that negotiations with Pyongyang were "not the answer".
Rahimi described the North Korean ruling system as one that "is not behaving sensibly", ruling out the efficacy of any military threat against such a country. Tuesday's ballistic missile launch prompted Abe to agree with U.S. President Donald Trump and other world leaders to compel the global community to step up pressure on Pyongyang.
The South's Joint Chiefs of Staff said in a statement that the seismic tremor was detected near the North's Punggye-ri test site.
Russia and China have created a roadmap for a settlement on the Korean Peninsula that is designed to promote the gradual easing of tensions and the creation of a mechanism for lasting peace and security, the Russian leader added. "A missile was sacked from North Korea".
"North Korea must find the path to negotiations".
"The hydrogen bomb, the explosive power of which is adjustable from 10 kilotonne to hundreds kilotonne, is a multi-functional thermonuclear nuke with great destructive power which can be detonated even at high altitudes for super-powerful EMP (electromagnetic pulse) attack on strategic goals", KCNA reported.
In what could be read as a veiled warning of more nuclear tests, Kim underlined the need for scientists to "dynamically conduct the campaign for successfully concluding the final-stage research and development for perfecting the state nuclear force" and "set forth tasks to be fulfilled in the research into nukes".