Nuclear Blast Map Shows Possible Impact on North Korea's Top Rivals

Modeling of a nuclear blast caused by a warhead with a yield North Korea is suspected to have developed and tested shows it could inflict widespread damage and kill hundreds of thousands of people if dropped on a population center of one of its international rivals.

There is heightened concern about its leader Kim Jong Un's nuclear program amid continued ballistic missile testing. On Wednesday, the G7 "strongly condemned" recent tests and called on North Korea to abandon its nuclear weapons, while an expert in Korean history said a build-up of its arsenal was a sign that it was "seriously preparing" for war.

North Korea has not officially confirmed the yield of the nuclear warheads it has tested and remains secretive about many other aspects of its nuclear program, so the international community has to rely on seismic waves produced by test blasts to estimate the payload.

When it last conducted a nuclear weapons test, on September 3, 2017, both NORSAR, a Norwegian seismic research organization, and AGU, a Washington D.C.-based earth and space sciences group, estimated a detonation equivalent to 250 kilotons of TNT.

However, AGU gave a possible yield of between 150 and 325 kilotons based on the tremors it caused, while NORSAR put the range between 200 and 300 kilotons. North Korea does not release any information about the nature of its tests, including the depth of testing sites and the density of the surrounding ground that could influence the seismic wave.

Assuming that it has a warhead capable of a 250-kiloton yield, were one dropped on Tokyo, Japan, it would destroy most buildings within a 1.7 square mile radius and would cause third degree burns to anyone within a 2.6 square mile radius, according to modelling by Alex Wellerstein, a professor and historian of nuclear technology.

Its impact would cover most of the Japanese capital's center, killing nearly 635,000 and injuring an estimated 2.3 million.

If detonated over Seoul, the capital of South Korea, most buildings would be flattened in the city while a blast radius would extend across several of its suburbs. An approximate 623,000 people would die and over 2.6 million would be injured.

A 250-kiloton nuclear bomb, if discharged over the White House, would vaporize it and Lafayette Square, as well as some of the surrounding buildings. The U.S. Capitol, the Supreme Court and the Library of Congress would be flattened, as would structures from the Washington National Cathedral to the Pentagon.

Nearly the entirety of Washington D.C.'s residents would suffer third degree burns, while a blast radius would extend from Bethesda, Maryland in the north to Alexandria, Virginia in the south. Nearly 339,000 would be killed and over 540,000 injured.

While its nuclear testing ceased in 2017, North Korea has continued to test the rockets it hopes to mount its nuclear warheads on—most recently on Thursday, when one was launched from near the capital, Pyongyang, flying 621 miles before falling into the waters off Japan, the South Korean military reported.

According to analysis by international security think tanks, the most powerful rocket to date, the Hwasong-15 intercontinental ballistic missile, may have a potential range of between 6,200 and 8,100 miles if fired at a flatter trajectory. Those ranges would allow one to reach the continental U.S., if not Washington D.C. and the East Coast.