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It looks like North Korea just detonated its biggest nuclear bomb yet

Seismic data shows a shallow 5.3 magnitude earthquake near the country’s usual nuclear test site.
Image via USGS

North Korea conducted its fifth and largest test of a nuclear weapon, according to early indications from geological data that shows a shallow earthquake near the country's usual test site.

The US Geological Survey recorded a 5.3 seismic event at 9:30 a.m. local time near the test site in Sungjibaegam, a remote area about 375 miles northeast of Pyongyang. The quake was recorded at a depth of zero, meaning it was almost certainly a nuclear blast.


Judging by the magnitude of the quake, which is not always reliable indicator, nuclear weapons expert Jeffrey Lewis estimated that the blast was roughly in the 20-30 kiloton range, the biggest on record for North Korea. That explosion would be roughly equivalent to the "Fat Man" bomb that the United States dropped on Nagasaki during World War II.

Mb=5.3 That's the largest DPRK test to date. 20-30 kt, at least. Not a happy day.

— Jeffrey Lewis (@ArmsControlWonk)September 9, 2016

Seismogram of today's M5.3 explosion in North Korea compared to their nuclear test from 8 months ago. — Andy Frassetto (@drrocks1982)September 9, 2016

Earlier in the week, North Korea launched three ballistic missiles that landed in the East Sea in Japanese waters. Afterward, state media reported that leader Kim Jong-un had "stressed the need to continue making miraculous achievements in bolstering up the nuclear force one after another in this historic year."

The nuclear test and missile launches occurred despite tightened international sanctions imposed earlier this year. Experts are still unsure whether North Korea is capable of fitting its nuclear bomb on top of a missile, which could potentially strike US military bases in the Pacific Ocean and potentially Japan, not to mention its neighbor South Korea.

Follow Keegan Hamilton on Twitter: @keegan_hamilton