How the recent blast compares to past tests

Norsar website

A comparison of the seismic readings of each of North Korea’s nuclear tests from Norway-based geoscience research foundation Norsar, which works to verify compliance wtih the Comprehensive Nuclear Test Ban Treaty.

“North Korea claims that this was a test of a hydrogen bomb; the same claim was made for previous tests,” Norsar said. “It is not possible from the seismic data alone to determine if this was a test of a hydrogen bomb, but we can say in general that the credibility of the claim increases with increasing explosive yield.”

By comparison, the “Little Boy” atomic bomb dropped on Hiroshima during World War II yielded roughly 15 kilotons TNT. The “Fat Man” bomb dropped on Nagasaki was about 20 kilotons TNT.

The most powerful nuclear weapon ever tested, meanwhile, is said to be a Soviet hydrogen bomb that yielded 50,000 kilotons TNT.

—Reuters contributed to this report.