What would happen if a nuclear bomb hit central Seoul?

Annie Jacobsen’s incredible book "Nuclear War: A Scenario" makes you wonder why there's a nuclear debate in Seoul.

Seoul, one of the most densely populated cities in the world, is home to over 9.7 million people in its core and 26 million in the greater metropolitan area. A nuclear detonation in the heart of the metropolis would bring unprecedented devastation, transforming the city into a wasteland of destruction and despair.

By examining the blast effects kilometer by kilometer, we can gain a glimpse of the human, environmental, and infrastructural toll this catastrophe would inflict.

When a nuclear bomb explodes, its destructive power is measured in terms of a fireball, a shockwave, intense heat, and deadly radiation. The effects on the population and infrastructure are determined largely by their distance from the blast’s center, or "ground zero."

Let's assume the detonation of a 1-megaton nuclear bomb in central Seoul, around Gwanghwamun Square, for illustration. The damage can be divided into specific zones, extending outward from ground zero.

0–1 Kilometer: Ground zero and total annihilation

Within the first kilometer radius of the detonation, the devastation is absolute. The fireball, reaching temperatures higher than the surface of the sun, would vaporize everything within this radius. Buildings, vehicles, and infrastructure would cease to exist, reduced to dust and ash. The heat and radiation would instantly kill nearly 100% of the population.

Gwanghwamun Square, including historic sites like Gyeongbokgung Palace and the major government buildings in Jongno-gu, would be obliterated in the blink of an eye. In less than a second, the shockwave would radiate outward, traveling faster than the speed of sound. Anything not vaporized by the heat—reinforced concrete buildings, for example—would be crushed by the force of the blast.

1–2 Kilometers: Firestorm and severe blast zone

Beyond 1 kilometer, but still within a 2-kilometer radius, the destruction remains extensive. While the core of the fireball itself would not reach this far, the intense heat would ignite widespread fires throughout the area, causing a firestorm. These fires would be fueled by the dense urban landscape, turning much of central Seoul into a sea of flames.

Buildings would be heavily damaged or completely collapsed. Structures made of glass, steel, and concrete would still be heavily compromised, while most residential and commercial buildings, such as those in neighborhoods like Myeongdong and Insadong, would collapse entirely. The pressure wave would shatter windows and send deadly shards of glass flying at high speeds, causing horrific injuries to anyone within this zone.

2–5 Kilometers: Severe radiation and blast damage

At a distance of 2 to 5 kilometers from ground zero, the impact of the explosion would remain deadly, though some structures may still be standing. Survivors would be exposed to extreme levels of radiation, known as the initial radiation, which is released in the first minute following detonation. The exposure could cause radiation sickness in as little as an hour, leading to a swift and painful death for most individuals in this zone.

Neighborhoods such as Itaewon, Yongsan, and the outskirts of the popular Dongdaemun market area would experience major structural damage. Most buildings would be destroyed or severely damaged, and the intense heat would still cause fires to erupt across the cityscape. The shockwave here would still be powerful enough to throw people through the air, hurling them into debris, resulting in fatal or critical injuries. Roads and transportation infrastructure would collapse, leaving the area impassable.

5–10 Kilometers: Moderate to severe damage zone

In the 5 to 10-kilometer radius, the effects of the blast and radiation diminish somewhat, but the destruction remains catastrophic. At this range, iconic areas such as Gangnam, Yeouido, and the outer edges of Yongsan-gu would face significant damage. The blast wave would shatter windows, collapse weaker buildings, and ignite flammable materials. Many high-rises in Seoul’s densely packed urban areas could partially collapse, and fires would continue to spread.

Radiation exposure here would still be dangerous, though not immediately lethal for those indoors or sheltered. There are more than 3,200 bomb shelters in Seoul. Most are not prepared as nuclear shelters and others have been reported to be poorly maintained.

The U.S. Command Post Theater Air Naval Ground Operations (CP Tango) complex located deep underground at an undisclosed location in the Seoul capital region is shielded by multiple blast-proof doors and serves as the primary headquarters to direct military operations against North Korea in the event of hostilities. It has  food and supplies for two months for up to 500 South Korean and US soldiers.

If you’re the same as me, you’re probably not invited. You can find out where to go here (good luck). Those of us exposed outdoors would suffer serious burns and would experience radiation sickness within days. Survivors would struggle to find medical help, as hospitals, clinics, and emergency services would be overwhelmed or destroyed.

10–20 Kilometers: Light damage and fallout zone

At a distance of 10 to 20 kilometers, while the most destructive effects of the blast and shockwave would be reduced, this area would face widespread infrastructure damage, along with exposure to radioactive fallout. The southern parts of Seoul, including neighborhoods like Jamsil and parts of Songpa-gu, would experience broken windows, damaged buildings, and fires, though many structures would remain standing. Survivors here would still be at risk from radiation sickness, as fallout—radioactive particles thrown into the atmosphere by the explosion—would begin to descend.

Radioactive fallout could blanket the area depending on the wind patterns at the time. In addition to fires, this fallout would contaminate the air, water, and soil, making the area dangerous for weeks or even months. Fallout exposure would cause long-term health issues such as cancers and genetic mutations in survivors. The population in this zone, especially those who did not have access to shelter immediately after the explosion, would be at high risk.

20–30 Kilometers: Peripheral damage and fallout

In the 20 to 30-kilometer radius, the physical damage to infrastructure would be less severe, but radioactive fallout would remain a serious concern. Towns and districts beyond the Seoul city limits, such as Incheon and Suwon, would begin to experience the deadly effects of fallout. Fallout particles, carried by wind currents, could settle over vast areas, leading to long-term radiation exposure.

While many buildings would remain intact, services such as electricity, water supply, and communications would be severely disrupted, leaving survivors without access to basic necessities. Emergency response teams would be unable to reach these areas due to the widespread destruction and high radiation levels closer to ground zero.

Long-term consequences

The immediate aftermath of the blast would be only the beginning of the city’s woes. Fallout would continue to rain down on Seoul for days, contaminating the environment and making vast swathes of the city uninhabitable for decades. The survivors who avoided the initial destruction would face severe health risks, including cancers and radiation sickness.

Beyond the human toll, the destruction of Seoul would have far-reaching economic and political impacts. South Korea, a global economic hub, would experience a catastrophic collapse of its economy, affecting industries such as technology, automotive manufacturing, and shipping. The global supply chain would face immediate disruptions, leading to economic instability in other regions of the world.

The detonation of a single nuclear bomb in central Seoul would result in the total collapse of one of the world’s most vibrant cities. The death toll would be in the millions, with survivors facing the harrowing realities of radiation sickness, environmental destruction, and societal collapse. The thing is, they rarely come as singles. A nuclear attack on Seoul would consist of multiple devices and a combination of artillery and potentially chemical and biological weapons. When the shit hits the fan, ain’t no one in this place escaping.

The once-thriving capital of South Korea would be reduced to a barren wasteland, forever changed by a single, catastrophic decision. North Korea would cease to exist as a functioning state and future history books would use Korea to explain the meaning Pyrrhic victory. It is a stark reminder of the unimaginable devastation that nuclear weapons can unleash and the necessity of continued efforts toward nuclear disarmament and global peace.

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This piece was composed after reading Annie Jacobsen’s incredibly frightening book Nuclear War: A Scenario. She details the impact of a nuclear war through time with a harrowing first twenty-four minutes, next twenty-four minutes, the final twenty-four minutes, and then the next twenty-four months. She starts the text with a prologue:

A 1-megaton thermonuclear weapon detonation begins with a flash of light and heat so tremendous it is impossible for the human mind to comprehend. One hundred and eighty million degrees Fahrenheit is four or five times hotter than the temperature that occurs at the center of the Earth’s sun.

Every line which follows is just as powerful. A must read for anyone thinking that nuclear weapons would make them safer or more secure. Read the book and one questions pops up - why is there a nuclear weapons debate in Seoul?

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