SEOUL — North Korea’s powerful nuclear test earlier this month may have been even stronger than first reported, equivalent to roughly 17 times the strength of the bomb that destroyed Hiroshima, according to a new analysis by a U.S. monitoring group.
North Korea’s Sept. 3 nuclear test, its sixth and biggest, showed how much progress it has made on its nuclear and missile program.
Preliminary estimates had found the yield, or the amount of energy released by the blast, to have been about 100 kilotons. In comparison, the bomb detonated over Hiroshima in 1945 released about 15 kilotons of energy.
But a new analysis by 38 North, run by the U.S.-Korea Institute at the Johns Hopkins School of Advanced International Studies, found North Korea’s test may have been much stronger.
Updated seismic data showed the magnitude of the resulting earthquake was greater than initial estimates — between 6.1 and 6.3. That means the yield of the latest test was roughly 250 kilotons, reported 38 North’s Frank V. Pabian, Joseph S. Bermudez Jr. and Jack Liu.
In other words, the North Korean test may have been almost 17 times stronger than the bomb detonated over Hiroshima. This is close to what 38 North previously calculated as the maximum yield that could be contained at the underground Punggye-ri test site.
This new estimate by 38 North is much higher than those of the U.S. government and its allies at the time. The United States intelligence assessment put the blast at 140 kilotons, Japan at 160 kilotons and South Korea at 50.
Satellite imagery showed the test resulted in many more landslides than after any of the previous five tests, according to the 38 North analysis.
North Korea described the device it had detonated as a hydrogen bomb designed to be carried by a long-range missile capable of reaching the U.S. mainland. The international community widely condemned the test and within 10 days, the U.N. Security Council unanimously approved its toughest sanctions on the country to date.
In the wake of the North Korean test, both the United States and South Korea are highlighting their own military readiness.
Defense Secretary Jim Mattis is traveling Wednesday to Minot Air Force Base in North Dakota, the epicenter of American nuclear arsenal, with more than 100 land-based nuclear missiles and aircraft to carry them.
While the South Korean Air Force on Wednesday conducted its first live-fire drill to test its preemptive strike capability, according to the South Korean Defense Ministry.