UH-OH

North Korea “earthquake” was its most powerful nuclear test yet

This is a developing story, last updated on Sept 3 at 3:37am ET.

North Korea said on Sunday (Sept. 3) that it has successfully conducted a hydrogen bomb test for use with an intercontinental ballistic missile, hours after South Korea and other nations detected a tremor near a site where Pyongyang has conducted past nuclear tests that caused seismic disturbances.

The US Geological Service put the magnitude of the seismic disturbance at 6.3 on the Richter scale, considerably higher than the tremors recorded in the country’s past nuclear tests. South Korean and Japanese officials have confirmed the test; South Korea’s meteorological service put the tremor at 5.7 (paywall). Norway’s NORSAR seismological observatory put the seismic magnitude at 5.8.

“The creditability of the operation of the nuclear warhead is fully guaranteed and the design and production technology of nuclear weapons of the DPRK [Democratic People’s Republic of Korea] has been put on a high level to adjust its destructive power in consideration of the targets and purposes,” said a statement by North Korea’s Nuclear Weapons Institute, carried by state-run news agency KCNA. The test was conducted at noon local time.

The institute also said “the recent test was carried out with the bomb of unprecedentedly big power,” but said that there was no leakage of radioactive materials.

South Korea’s state-run news agency Yonhap quoted the chief of the country’s parliamentary defense committee as saying that preliminary information suggests an explosion up to 10 times more powerful than the last one North Korea conducted. Pyongyang’s last nuclear test, its fifth, was on Sept. 9, 2016, a national holiday to mark the foundation of the communist state, and registered a tremor of 5.3 in magnitude.

Other countries also noted the difference. The estimated explosive yield would make this device five times more powerful than the bomb dropped on the Japanese city of Nagasaki in 1945.

The latest test came just hours after North Korea said it now has advanced hydrogen-bomb capabilities, according to a report from the state-run Korean Central News Agency after the country’s leader Kim Jong-un visited a weapons facility in Pyongyang. Kim met with nuclear scientists and “watched an H-bomb to be loaded into new ICBM,” KCNA said.

North Korea first said it had tested a hydrogen bomb in January 2016, a claim that was met with skepticism. Hydrogen bombs are far more powerful than atomic bombs and the seismic pattern generated by the 2016 explosion wasn’t substantially larger than in North Korea’s previous nuclear tests. The January test was a 5.1 seismic event.


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