These maps show how much damage a North Korean thermonuclear weapon could do to major American cities

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Nuclear weapons may be humanity's most terrifying creations, but most people would be hard-pressed to say what, exactly, such an explosion might do to their town or city.

To help the public get a handle on nuclear threats, Alex Wellerstein, a historian of science at Stevens Institute of Technology, created Nukemap: an interactive simulator that lets you set off a nuke anywhere on a world map.

A recent update even lets you predict where clouds of radioactive fallout might drift based on current weather.

"A realistic understanding of what nuclear weapons can and can't do is necessary for any discussion that involves them," Wellerstein previously told Business Insider. "People tend to have either wildly exaggerated views of the weapons, or wildly under-appreciate their power."

Given rising public interest in North Korea's intercontinental ballistic missile and nuclear test programs, Wellerstein recently added the isolated nation's Sept. 3 underground blast — its most powerful yet — to a list of preset options in Nukemap.

The device may have been a thermonuclear bomb since it yielded an explosion of roughly 150 kilotons' worth of TNT. That's about 10 times as strong as the Hiroshima bomb blast of 1945, which inflicted some 150,000 casualties.

Although a nuclear-tipped North Korean missile couldn't reach most of the continental US (yet), and casualties are notoriously tough to estimate, the images below show what could happen if a 150-kiloton warhead hit major American cities.

We chose the 10 following US cities because they are the most densely populated, and ranked them based on estimated loss of life.

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We used Google Earth Pro to 3D-illustrate each scenario from Nukemap (which now has a convenient export feature to the app). Here's what the blast result colors mean:

Yellow: Fireball (0.56 miles wide, 1.03 miles high) — In the area closest to the bomb's detonation site, flames would incinerate most buildings, objects, and people.

Green: Radiation (1.24 miles wide) — A nuclear bomb's gamma and other radiation are so intense in this zone that 50% or more of people die within "several hours to several weeks," according to Nukemap.

Blue-gray: Air blast (4.64 miles wide) — This shows a blast area with 5 pounds per square inch of pressure, which is powerful enough to collapse most residential buildings and rupture eardrums. "Injuries are universal, fatalities are widespread," Nukemap says.

Orange: Thermal radiation (6.54 miles wide) — This region is flooded with skin-scorching ultraviolet light, burning anyone within view of the blast. "Third-degree burns extend throughout the layers of skin and are often painless because they destroy the pain nerves," Nukemap says. "They can cause severe scarring or disablement, and can require amputation."

Tampa, Florida: 67,000 dead, 161,000 injured

The blasts we use to estimate deaths and injuries are 150-kiloton airbursts detonated about 1 mile above the ground. Nuclear weapons inflict the most damage as airbursts — detonating the bombs hundreds or thousands of feet above a target spreads blast energy more efficiently. That makes a bomb more deadly than if it were detonated on the ground, since soil and structures can absorb or block some of that energy.

This 150-kiloton blast over Tampa could destroy:

- 54 hospitals and medical facilities
- Two fire stations
- 46 schools and educational facilities
- 74 churches, synagogues, mosques, and other places of worship

In the event of a 150-kiloton surface detonation in Tampa, the nearby city of St. Petersburg may get a deadly dose of fallout.

Airbursts create little radioactive fallout compared to surface blasts, which suck up debris, irradiate it, and spread it for hundreds of miles. An airburst strike isn't guaranteed, however, so we've included predictions of fallout clouds from ground detonations to provide a sense of how far this threat can travel.

We used Nukemap's estimation of where fallout would travel based on the prevailing winds on Thursday, October 12. We'll note, however, that fallout clouds usually take on a more complex shape due to high-altitude winds.

See the rest of the story at Business Insider