Atomic bomb's explosive power

I'm working on a world where technology and magic exist together and wanted to develop the weaponry humans would create. But to do that, I need to first know how far our race has actually gone.

If you take modern nuke, how big of explosion would it cause?

Conditions:

- no radiation (I just want to know the damage caused by initial boom, not what radiation does afterwards)

- city is on flat terrain

What is the radius that will be completely vaporized? (I know it depends on how big nuke is, but if possible, please add the smaller and bigger ones and what is between them)

Also, maybe someone can imagine what happens if nuke detonates on top of Mount Everest? How much of the mountain will disappear?

edited 5th Jun '15 2:17:48 PM by gtrhnetyy

Here's a few charts:

http://cache.wists.com/thumbnails/a/9f/a9f7e8fdf4b4c006189d897c99422282-orig

Nukemap is your friend here. It's just one of several utilities for calculating the effects of a nuclear weapon.

Note that fireball radius does not scale linearly to power, and keep in mind that the radius of destruction varies on the altitude of the burst. A groundburst will scour a target from the ground, but the geographical area affected will be much less than an airburst. (If you model the explosion as a sphere, it will be evident that in a groundburst only the equator of that sphere will expand outward usefully to cause destruction; if you lift that sphere into the air so that it doesn't intersect with ground, fully half its surface area will cause damage to the ground.) This doesn't take into consideration the effects of terrain on the blast wave.

Go into my profile and under the section weapons of mass destruction there are a few links to stuff you may be looking for.

You can also read the TV Tropes page on The Deadliest Mushroom.

Nukes work best against surface targets when detonated some distance above the surface, to give a substantial amount of air that can be compressed by the explosion and damage a wider area. This also reduces the damage they actually cause to the ground itself. You can excavate far more dirt by detonating the nuke on the Earth's surface or under the ground, but that will reduce the radius of damage to targets standing on the ground.

The largest nuclear test to ever take place constituted a yield of about 50MT TNT-equivalent (2.1*10¹⁷ joules). When detonated at an optimal altitude above flat terrain during dry weather, this is considered sufficient to destroy normal concrete buildings and infrastructure within a radius of about 30km around the point directly below the detonation. At a distance of 100km, wooden buildings are still flattened and unclothed humans receive crippling, potentially lethal burns. The radius of vaporization (not a normal measure of the effectiveness of nuclear weapons, as far as I know) would be considerably less than the 30km figure and would depend a lot on what you actually want vaporized.

The 50MT midair detonation would excavate a few meters of dirt in a radius some kilometers around the point below the bomb. The same yield detonated at ground level on flat terrain would likely excavate a few dozen meters of solid rock, or as much as 100 meters of loose earth. An optimally placed underground detonation would produce a crater several hundred meters deep and a few kilometers in diameter. Mount Everest is mostly rock near the peak, but is not a flat surface; a 50MT detonation at the peak would probably remove on the order of 50 to 100 meters from the mountain's height, but the vast majority of this material would merely be displaced onto the lower surrounding terrain, not vaporized.

Most nukes are not as big as the one described above. For a variety of reasons, modern nuclear weapons (pretty much any built since the 1960s) are generally smaller, with strategic warheads being on the order of a few hundred kilotons while tactical warheads can be under one kiloton. The combined yield of all existing nuclear stockpiles is estimated to be about 7GT. For nuclear weapons of the sizes built and used by humans under terrestrial conditions, effect radius scales roughly with the cube root of energy yield.

Air burst nukes work best against a surface target. Against underground hardened bunkers other delivery and weapon systems are used. Same for sea based nuclear weapons.

For bunkers there are nuclear bunker busters which are just a bunker buster type weapon with a nuclear warhead that penetrates into the ground before detonation. The other more common method is called laydown method. The weapon has a parachute or other fall retarding device that causes the weapon the land on the ground and basically lay against the surface before going off. Basically a variation on the surface burst type of nuclear attack.

For sea warfare there are nuclear depth charges and torpedo's for use against both subs and surface ships. Subsurface nuclear detonations can produce a lot of contaminated water depending on the conditions.

^ And also subsurface detonations in water are a lot more lethal than airbursts when it comes to ships. Operation Crossroads proved warships were more resilient to nuclear attack by airburst than anyone ever thought.

True to a point. It was capable of causing serious damage over a small area but it was the radiation that was the most lethal factor. It is also true in terms of outright damage to the ships a sub-surface burst was a lot more destructive including tossing a battleship like a bath toy. It also created a massive radioactive base surge that effectively permanently contaminated several ships.

Radiation aside, if you want to sink ships with nukes you blow em up from below. I mean if you blow up a tac nuke over a Nimitz today, sure flight ops are out of the question and the ship is probably an absolute mess topside but it's easily salvageable as far as sinking damage is concerned. But take said tac nuke and blow it about 50 meters underwater and that Nimitz will be both turned turtle and sunk from a buckled hull. I think the shockwave effect is similar to cavitation.

Actually an airburst is capable of doing significant damage to even an aircraft carrier. The Able and Baker shots from Operation Crossroads point out a few important factors. For the air burst the ships position and bow to stern orientation to the blast coupled with other factors like presence of volatile materials on the vessel can have a myriad of effects. Finally radiation contamination is actually the more effective in causing lasting problems and rendering a vessel useless and full of dead and dying crew.

For the Able shot which actually missed it's target, the vessels that were broadside to the blast wave received significant and even serious damage. Ships that were stern or bow on suffered notably less damage. The aircraft carrier Saratoga a mile away from the blast caught fire from the planes and avgas. Another aircraft carrier that was a lot closer also suffered severe damage. That was just using sample loads not fully loaded aircraft carrier. Further the test animals on the ships proved the radiation even from inside the heavily armored battleship gun turrets was a serious concern. Onset of radiation sickness was quick and every crew member aboard would be disabled or severely hampered in about day or two at most and dead in no more then four from radiation.

The Baker shot demonstrated that while the subsurface burst had a great destructive potential the area of effect was more limited. It was the base surge and extensive contamination that was far more effective as it affected far more targets contaminating them permanently. Both types of burst were capable to causing serious damage even sinking ships.

Both shots area of serious damage was out to 1,000yds.

The number of land target experiments get really interesting with things like Operation Plowshare while overtly an attempt to demonstrate and find non-military uses for nuclear weapons many reasonably argue it was barely concealed weapons testing program.

edited 6th Jun '15 10:53:00 AM by TuefelHundenIV

My deepest gratitude for everyone! This is more than I had dreamed to hope!

@ Meklar

Special thanks for answering my silly Mount Everest question.

Something came to my head thinking of this. Sephiroth Survived that meteor that shattered the entire surface of the planet. So we already know one character who could survive the nuclear blast, the force of it anyway. The radiation would probably kill him after awhile.

Maybe study one of those radiation eating fungi for a spell for that too, assuming it isn't just used for the spell.

edited 6th Jun '15 3:43:12 PM by IndirectActiveTransport

As far as I recall even the large meteorite strike won't unleash huge amounts of radiation in the same way a nuclear weapon would. They contain very little radioactive material in them where as a warhead for a bomb is made with refined reactive material.

Especially if you compare the same power from a weapon as the meteorite the weapon releasing the same amount of energy is also dumping more radiation because of how it works.

edited 6th Jun '15 4:40:42 PM by TuefelHundenIV

It won't. Even if you had a "nuclear meteorite" that was a major radiation maker somehow.

Meteorite impacts are hypervelocity, they disperse ejecta (and thus fallout) according to their impact profile. Meaning if the "nuclear meteorite" came down near vertical its debris and ejecta from the crater will likewise go mostly vertical. Newton's Laws remember? Every action an equal and opposite reaction.

Now impacts do have lateral effects and I'm not referring to more oblique angles of impact. But they are less defined and controlled than an airburst nuke. For example the Tunguska Meteor blew an irregular, non-circular pattern of terrain damage along the way it was coming down. Berringer Crater in Arizona while circular in appearance definitively shows the object came down at an angle and thus would have pushed more ejecta a certain way than any other.

All this made shorter, it's an unreliable mechanism for fallout dispersion.

Tom: You do remember the large meteorites threw material into the sky that went around the globe right? Sort of like how ash from a volcanic eruption can do the same thing. An actual nuclear meteorite would completely change everything we are talking about and frankly is very silly.

^ A meteorite large enough to cause a planetary winter doesn't need radioactive fallout to begin with.

Yup, especially since fallout is relatively short-lived compared to the sheer damage that would wreak.

After a generation or two, most of the radioactive elements will have decayed to inertness. You're going to see things like increased stillbirths and deaths to cancer in the population for quite a while, and within those two generations there will be large tracts of land you would not want to live in, but compared to the more immediate effects of starvation and its associated second-order effects, the increased mortality due to radiation will be hardly noticeable.

Also, as my fellow threadgoers have pointed out: fallout is a result of groundbursts or low airbursts. If the fireball doesn't touch the ground, fallout will be minimal. Counterintuitively, counter-value airbursts aimed at cities may do less damage in terms of fallout than counter-force groundbursts.

edited 8th Jun '15 7:38:36 PM by SabresEdge

Tom: That is exactly what fallout is. A substance or material thrown into the air that can linger for undetermined periods or settle. In terms of radioactive material that can contaminate large swaths of land many many miles away from the initial sight depending on prevailing winds.

Not entirely sure what you mean by a nuclear meteor but if you are talking about a meteor composed entirely of refined or even unrefined fissile material there is a good chance that the heat and pressure from an impact would initiate some sort of reaction. Keep in mind we use conventional explosives to generate comparatively smaller levels of heat and pressure to set off atomic weapons. As for unrefined material it is entirely possible for it to react. Naturally occurring "reactors" have been found after the eventually burned out.

As for the reaction itself it would be a ground level burst and I doubt it would be as efficient at consuming its fuel and would be like a really damn big dirty or salted bomb going off.

Sabre: Fallout is not that short lived in terms of human life especially from dirty bombs or dirty detonations and god help you if they are salted bombs. It depends on the level of contamination and whether or not the weapons are used to purposefully contaminate the target area. Both Chernobyl and the Bikini islands are still considered to dangerously contaminated to this day for common human habitation. Using bombs that are less efficient or salted to deliberately create a much more hellish landscape would make things a lot worse then a meteor impact of comparable output. Even the "clean bombs" still put out contaminating fallout. The term clean is used in a relative sense. A 5 megaton meteor strike is going to far nicer on everyone then a 5 megaton ground burst bomb even if it was a clean bomb it would still throw a lot of fall out into the air.

In terms of survival radiation poisoning and the extensive destruction caused by a bomb is far more immediate. Trying to live in contaminated zone even if it contained adequate food and water would have a notably negative impact on human survival as they would consume contaminated material and be exposed to it. If you want to start talking about dirty bombs or salted bombs it gets even worse.

Blow for blow a nuclear weapon of equal yield to any meteorite impact will have a far larger short term and long term impact. Meteorites simply do not measure as a weapon or disaster in terms of damage or long term effects.

edited 9th Jun '15 7:36:42 PM by TuefelHundenIV