January 6 2021 — On January 6 2016 (at 10:00:01 UTC+08:30), North Korea conducted its fourth nuclear detonation at the Punggye-ri Nuclear Test Site, approximately 50 kilometres (30 miles) northwest of Kilju City in Kilju County. Follow us on Twitter: @INTEL_TODAY
RELATED POST: CIA Establishes Korea Mission Center
UPDATE (January 6 2021) — On October 9, 2006, North Korea conducted its first nuclear test. That event prompted me to blogging. Here is the story.
Beside the time and the location of the “event”, seismic waves can also reveal the magnitude of the explosion.
In very good approximation, the magnitude of body waves is proportional to the logarithm of the yield in kilotons: Mb = 4.26 +0.97 log (Y). [A kiloton is equivalent to 1,000 tons of TNT.]
On October 9 2006, the author used this equation to estimate the yield of the first North Korea nuclear test at 0.2 kiloton.
At the time, this estimate was in contradiction will all reported analysis that had estimated the yield at several kilotons!
On October 17 2006, the office of John Negroponte — the then US National Intelligence Director — finally admitted that the size of the explosion was indeed less than 1 kiloton.
Using a simple pocket calculator, I had obtained the right result long before the CIA.
RELATED POST: One Year Ago — Libyan Nuke Program Was CIA-MI6 Sting Op
That story and two other CIA nuke-related big lies — the nonsensical narrative regarding A. Q. Khan and the fictitious Libyan nuclear project — encouraged me on the path to blogging.
But it all started on October 9 2006 when I decided to do a quick fact-checking of the New York Times.
END of UPDATE
North Korean media announced that the country had successfully tested a hydrogen bomb in ″self-defence against US″.
However, third-party experts as well as officials and agencies in South Korea questioned North Korea’s claims.
Most experts contend that the device was more likely to have been a fission bomb such as a boosted fission weapon.
The test was conducted ahead of Kim Jong-un birthday (January 8, 1983).
The US Geological Service reported a 5.1 magnitude quake while the China earthquake network centre gave the magnitude as 4.9.
UPDATE (January 6 2020) — It looks like 2020 started on the wrong foot… In just a few days, Iran has announced its withdrawal from the Nuclear Deal and North Korean leader Kim Jong Un said his country no longer feels bound by its self-imposed suspension on nuclear weapons and long-range ballistic missile tests. Happy Nuke Year?
END of UPDATE
On This Day — North Korea Tests H Bomb in “Self-Defence Against US” (January 6 2016)
On This Day — North Korea Tests H Bomb in “Self-Defence Against US” (January 6 2016) 
5 Years Ago — North Korea Tests H Bomb in “Self-Defence Against US” (January 6 2016)