What Would Happen If We Detonated an Atomic Bomb in a City?

The possibility of a nuclear apocalypse never completely disappeared. In the past we've simulated atomic detonations in your browser, and even explored certain strategies to survive an event of that magnitude… under some rather optimistic conditions. The folks at Kurzgesagt decided to return to the nuclear theme from a different perspective: A high-yield bomb, one city. What happens in the first seconds, and how does the chaos unfold in the following hours?

We can think of terrorist attacks, a submarine captain losing his mind, or an unforgivable protocol error inside a silo. But none of that matters today: the point is that a high-yield nuclear bomb falls and explodes over a densely populated city in full activity. The so-called “first phase” of the detonation occurs in the first second. A fireball hotter than the Sun reaches a diameter of two kilometers, turning everything it touches into vapor.

(N. del R.: Spanish subtitles available!)

The Thermal Pulse

The intense brightness of the detonation is accompanied by a thermal pulse, which can carry so much energy that it will ignite everything within a radius of 13 kilometers. Remember the bomb scene in Terminator 2? One of the most disturbing aspects is that it's not far from reality. Wood, plastic, fabric, skin, hair, and human flesh, in flames.

The Shockwave

The second phase begins with the shockwave. The heat and radiation from the fireball form a bubble of superheated, compressed air around it, which starts expanding at a speed greater than that of sound, creating winds that surpass the most lethal hurricanes. Infrastructure disappears: all larger buildings within the first kilometer after the fireball are reduced to their base, and only steel-reinforced concrete manages to offer minimal resistance.

The damage spreads over about 175 square kilometers, trapping tens of thousands of people who had no time to react. Fire and explosions multiply among the ruins, and the gigantic mushroom cloud created from the remains of the fireball, ashes, and dust begins to gain altitude rapidly and covers the city in darkness. The evolution of the cloud forces air to enter the city, which besides destroying more buildings, increases the amount of oxygen for existing fires. If enough “fuel” remains in the region, the current turns into a firestorm. The blast wave reaches a maximum distance of 20-21 kilometers, shattering every piece of glass in its path.

The Aftermath

Finally, the third phase begins a few hours after the explosion and lasts for days. A nuclear detonation equals all natural disasters simultaneously, with hundreds of thousands of people suffering severe injuries. In those initial hours, thousands will die. People trapped in the rubble, blinded by the light and deafened by the blast, confused and terrified define the scene. Hospitals and clinics destroyed, medical professionals dead or injured… local assistance is nonexistent. Even those who managed to escape the nuclear fury in the subway will have to fight to survive. Depending on the type of bomb and the weather, we also have to consider radioactive fallout. Ash and poisonous dust covering the whole city. Those exposed to larger doses will die in a few days; others will take years suffering from cancer variants like leukemia.

Without electricity, without water, without food, without roads, without communications. Any effort from nearby cities will take days to enter the city, with very high risks due to the aforementioned radiation, and a guaranteed sanitary collapse. Thus the cruel truth is revealed: There is no appropriate humanitarian response to the explosion of a nuclear bomb. The concept of immediate aid is nonexistent.