The state of Hawaii is recalculating the effects of a nuclear missile strike on the isles after North Korea on Sunday conducted what experts believe was a more than 100-kiloton nuclear test that may have been a hydrogen bomb.
By comparison, the U.S. atomic bomb dropped on Hiroshima in 1945 was 15 kilotons.
The North’s nuclear program under Kim Jong Un, progressing at breakneck speed, has Hawaii, the nation and allies like Japan and South Korea struggling to cope with the mounting threat.
“It is very difficult” to develop a response plan with the rogue nation’s technological advances, said Vern Miyagi, administrator of the Hawaii Emergency Management Agency. The North is expected to test-launch another intercontinental ballistic missile, likely over Japan, at any time.
As part of a new preparedness plan for Hawaii residents and emergency responders, state officials postulated a 15-kiloton North Korean nuclear device detonated 1,000 feet above Honolulu. North Korea’s September 2016 underground detonation is thought to have yielded 10 to 15 kilotons.
Miyagi said the state, one of the first in the nation to begin planning for the possibility, however small, of a North Korean missile attack, is now examining the effects of 100- and 150-kiloton strikes.
“We have requested additional information on the effects of a larger warhead based on last weekend’s test,” Miyagi said in an email. There will be “adjustments and recalculations” to planning, he said.
The response plan was designed to be scalable, and now it is being sized up. “The effects of the (North Korean) advances may change, however, our basic planning continues,” Miyagi said.
A nuclear strike modeling site put together by Alex Wellerstein, an assistant professor at Stevens Institute of Technology in New Jersey who studies nuclear weapons, predicts 156,000 fatalities and 139,000 injuries from a 100-kiloton explosion at 1,140 feet over downtown Honolulu. Wellerstein’s “NUKEMAP” modeling projects that heavily built concrete buildings would be severely damaged or demolished within nearly a mile of the air blast, while third-degree burns would be experienced out to 2.87 miles.
The change to Hawaii Emergency Management planning, meanwhile, comes as the state continues a phased approach to preparedness for a possible North Korean nuclear threat.
Phase 1 planning in a pre-strike environment focuses on improving emergency notification and warning, developing public education and response guidance to be completed by the end of this month, Miyagi said.
Phase 2 follows a notional nuclear attack and includes planning for immediate response and recovery operations, damage assessment, emergency medical care and fatality management, radiological monitoring/decontamination, communications and restoration of essential services. The goal is to have the planning done by the end of October, according to Miyagi.
At 11:45 a.m. Nov. 1, residents statewide will hear for the first time in decades an “attack warning” wavering tone in conjunction with the regular “attention alert” for threats such as hurricanes or tsunamis, officials said. The attack warning, a throwback to the World War II air raid sirens used in Hawaii, has not been used in the state since the end of the Cold War.
North Korea said its Sunday underground nuclear test, its largest ever, was a successful H-bomb demonstration for use in ICBMs. The seismological observatory Norsar in Norway estimated the explosive yield at 120 kilotons. ABC News reported that U.S. intelligence assessed it was “highly probable” North Korea detonated a hydrogen bomb, which is a more powerful nuclear device, and that the yield was more than 140 kilotons.
In an Aug. 30 Bloomberg news story before Sunday’s test, Gen. Paul Selva, vice chairman of the Joint Chiefs of Staff, said “it is clear” North Korea has missiles that can reach the United States, but it has yet to demonstrate it has the guidance and stability control and re-entry vehicles for a successful attack.
Hawaii would have just 20 minutes from launch of a North Korean ICBM until impact.
Hawaii Emergency Management has guidance on its website and a “frequently asked questions” section. Surviving the immediate effects of a nuclear detonation, including blast, shock, thermal radiation and initial nuclear radiation, requires sheltering immediately in resistant structures, the agency said.
One of the questions answered is whether planning for a North Korean attack is futile given the high casualty rate.
The answer given as of Aug. 8 was that “current estimates of human casualties based on the size (yield) of North Korean nuclear weapon technology strongly suggests an explosion less than three miles in diameter. More than 90 percent of the population would survive the direct effects of such an explosion.”
How the assessment will change remains to be seen.
The question also was asked: “Are the neighbor islands safe?”
“We do not know,” Hawaii Emergency Management said. “North Korean missile technology may not be adequately advanced to accurately target a specific island or location. Although most analysts believe the desired target will be Oahu given the concentration of military and government facilities, a missile may stray and impact the open ocean or even a neighbor island. All areas of the state of Hawaii must consider the possibility of missile impact.”