No one wants to contemplate the prospect of a nuclear weapon exploding over MacDill Air Force Base.
Yet the base is home to two of the U.S. military's most important commands and more than a million people live in the surrounding metro area. So there are people who are charged with not only imagining such an event, but figuring out the extent of the damage and how to respond.
Alex Wellerstein, an assistant professor of science and technology at the Stevens Institute of Technology in New Jersey, is one of the people who study the potential effects of a nuclear weapons strike. He developed a well-regarded website, nuclearsecrecy.com/nukemap/, that allows users to pick a target and the size of the bomb and develop a model of the explosion's impact.
According to Wellerstein's website, here's what would happen if a 20-kiloton nuclear device similar to that being developed by North Korea were detonated over MacDill:
The blast — roughly as powerful as the "Fat Man" bomb dropped on Nagasaki on Aug. 9, 1945 — would leave a 100-foot deep crater at the epicenter with a radius of 170 feet. The headquarters of U.S. Central Command and U.S. Special Operations Command would likely be destroyed or heavily damaged. Nearly everyone within a half-mile of the explosion would be killed immediately.
Nearly a mile out, 80 percent of the people would die from radiation poisoning, with death taking from between several hours to several weeks. Radioactive fallout would spread, driven by winds, sickening thousands, who would see their cancer risks increase over time as a result.
Experts agree a North Korean attack on MacDill -- or any site in the U.S. -- remains highly improbable at the moment. The North Koreans still aren't believed capable of accurately delivering a nuclear warhead. And while their Hwasong-14 ICBM can reach the east coast of the United States, it can't yet reach Florida, according to nuclear weapons expert Karl Dewey of Jane's by IHS Markit.
But in the wake of mounting global tensions, exacerbated by threats from North Korean despot Kim Jong un and strong responses from President Donald Trump, local public safety officials say it may be time to improve training in how to deal with the aftermath of a nuclear attack.
"Anytime new threats come up, we try to incorporate it," says Tampa Fire Rescue spokesman Jason Penny.
One possibility is a "tabletop exercise" often used by safety officials to work out responses to developing situations. While such drills are used in planning for hurricanes, plane crashes, a so-called "dirty bomb" radiological device or any of the myriad ways bad things happen to large numbers of people, responding to a nuclear missile strike hasn't been specifically covered yet. But that could change.
Ashley Bauman, a spokeswoman for Tampa Mayor Bob Buckhorn, said such a table top exercise might be considered in the future with input from regional, state and federal partners.
"We might consider such an exercise,'' said Tampa Police spokesman Steve Hegarty. "We usually are dealing with some scenario based on current events.''
Hillsborough County already has plans in place to deal with the aftermath of a nuclear blast, said Preston Cook, the county emergency management director.
One key job: With help from federal and local partners, determining when it was safe to rescue and treat survivors.
The state plans for a wide array of radiological events, including terror attacks on nuclear power plants, stolen nuclear weapons, nuclear weapons detonations, so-called dirty bombs, and accidents involving transportation of radioactive materials or industrial accidents.
Less than a millionth of a second after a nuclear warhead explodes, a fireball starts to form, generating tens of millions of degrees of heat, according to a Princeton University study.
During the fireball's expansion, vaporized matter condenses to a cloud containing solid particles of weapon debris. The fireball becomes doughnut-shaped, with violent internal circulatory motion and eventually turns into a mushroom cloud. Pressure waves develop immediately after explosion and move outward from the fireball.
In the first minute, nuclear radiation, in the form of neutrons and gamma rays, is released.
According to Wellerstein's online model, most of the residential buildings just outside the base south of Interbay Boulevard would collapse, with everyone injured by the heat suffering third-degree burns.
Further out, Monroe Middle School and most of the homes in the Sun Bay South neighborhood would experience broken windows. The people living there would receive first-degree burns, which heal in a few days.
Meanwhile, plumes of radiation would spread for 100 or so miles, driven by the wind, causing additional death and sickness.
Anyone who survives the blast is urged to duck and cover for at least two minutes upon seeing the flash, according to the state's emergency response plan. Then remain sheltered in place, underground if possible, but in the center of a middle room in a large, stable building. If home, go to a basement or ground floor room furthest from the outside. Close windows and doors and be prepared to stay there for up to two days.
Still, with thousands instantly killed on the base, and many thousands more injured and sickened by radiation, panic would fill the region.
According to the state's Radiological/Nuclear Incident Response Plan, developed in 2011, the blast would invoke an immediate federal government response due to the significant national and international ramifications.
Initially, state and local authorities would have to deal with the chaos. But the plan calls for them to be augmented by federal resources as soon as they become available.
Cook, Hillsborough's emergency management director, said the county's response would depend on the extent of the damage. Under the Wallerstein map, MacDill itself would be considered a hot zone, with no access for emergency crews. Teams would then try to determine other areas where survivors can be treated, Cook said.
The county health department would coordinate the various agencies providing public health and medical services. First-responders from all over the region would rush in to help, according to state plans.
The Florida National Guard's 48th Civil Support Team, created to handle various disasters, including weapons of mass destruction events, would head to the scene from their headquarters in Pinellas Park, set up communications systems and conduct radiation testing. The state's Bureau of Radiation Control would assist in providing personnel and equipment.
MacDill officials declined comment on how they would react.
Meanwhile, area hospitals would be overwhelmed.
"We can't handle thousands of patients," said Tampa General Hospital spokesman John Dunn. "We've participated in drills where the county and health department set up large triage areas at the fairgrounds. Under those scenarios they would handle the initial medical conditions and then determine where to send those patients based on medical need and availability."
Hillsborough schools, with more than 200,000 students, would "take direction from the Governor's Office or Homeland Security in the event of a catastrophic event," said schools spokeswoman Tanya Arja. "If school was in session, in general we would follow our site threat continuum, which we have protocols in place regarding shelter in place."
Tom South is one of the few people in the region to have witnessed a nuclear explosion.
"I can't imagine anything more disagreeable than what I saw," he said.
On March 1, 1954, South was a seaman aboard the seaplane tender USS Curtiss. Anchored about 20 miles from Eniwetok Atoll in the western Pacific Ocean where Castle Bravo, a 15-megaton thermonuclear device, was detonated, South and his crewmates witnessed an explosion 1,000 times more powerful than the bomb dropped on Hiroshima, according to the U.S. government.
"If you have not physically been present at one of the tests they had over the years, there just is simply no comparison to seeing it on film," said South, now 83 and living in Tampa. "It is a devastating experience."
Contact Howard Altman at email@example.com or (813) 225-3112. Follow @haltman.