Damage at Hiroshima and Nagasaki 9700 lb weight

Damage at Hiroshima (and Nagasaki) 9700 lb weight, yield 16 KT (initial estimate 13 KT) 600 -800 mg converted to energy Altitude of detonation: 1680 ft (600 m) Scaling from 1 KT: (equiv 667 ft) Ground zero: 45 psi 1000 ft: 30 psi 6000 ft: 4 psi 2000 ft: 20 psi 8000 ft: 3 psi 3000 ft: 17 psi 10, 000 ft: 2 psi 4000 ft: 10 psi 15, 000 ft: 1 psi Nagasaki yield 21 KT But terrain more Uneven, damage less.

Blast effects

Damage to commercial / government type structures Building. 12 miles from ground zero, Hiroshima. Blast was largely downward.

Same building, interior (gutted by fire also) Note many structural elements are damaged but still in place

Another reinforced concrete building, . 13 miles from GZ, Hiroshima Clearly massive failure but some of building still stands. Comparable to Damage you would see from nearby terrorist truck bombs (e. g. OK City)

Another building near ground zero Notice the dished in (but still substantially intact roof. This is another case of heavy vertical loading. Note also the wall missing on the left side (as seen through the windows). The missile Hazards inside would have destroyed anything, even without the fire.

Concrete slab construction near Ground Zero

Farther from ground zero: more horizontal loading

Iconic Hiroshima image Because the loading is More horizontal, the Building structures are Less designed to Withstand the shock. You see this image Quite often in history Books and other Sources describing The damage at Hiroshima.

Concrete and steel farther away vs Industrial Steel frame buildings Front right and back center (across river) are remains of steel frame industrial sites. The framing still stands in places but covering is removed. This is. 85 miles from ground zero, Nagasaki. Note the substantially intact concrete and steel building at left back center.

Light steel frame building: only the frame survives, and that’s distorted. (It’s hard to know how much of the damage is from blast, how much from fire. ) Note: I believe today’s “big box” retail stores would fare as bad or worse.

Destroyed light steel frame buildings, Nagasaki

Smaller light steel buildings (Nevada) This type of construction is very common in the USA. (3 PSI seems A bit much For this kind Of structure. )

Similar building and circumstances, Nevada This was also a 3. 1 PSI case. Here the frame Buckled but the Room stayed More intact. Steel Is good at absorbing Energy and failing In a ductile manner. Same Structure, after

Interesting variation: Self framing corrugated steel This structure was built from 43 inch wide, 16 gauge corrugated steel panels. It did relatively well compared to the conventional light steel frame structures. (3. 1 PSI overpressure)

What about windows? Light steel frame construction with, without 6. 5 psi overpressure, 1. 1 psi dynamic pressure (positive pulse. 9 sec. ) 3. 5 psi overpressure and. 3 psi dynamic pressure, . 3 sec pos pulse (not really comparable. )

Residential Structures: Hiroshima Wood frame house 1. 0 mile from ground zero, Hiroshima At right, photo of a similar house Under construction, to show the Framing. Traditional Japanese structures are built with earthquakes in mind. They are likely to survive Better than conventional frame Houses in the USA.

Before and After for a wood frame house at 5 psi (Nevada) This is what you see in Photos of tornado damage. You want to be in the basement, if you have one.

Similar house, but 1. 7 psi. Survivable

If strengthened (as desirable in earthquake zones) houses do better. At 2. 6 psi (below) Damage may be A bit less than the Unreinforced house At 1. 7 psi. Not bad. Above house was hit by 4 psi overpressure. The roof has failed but the structure is fairly Intact. (Compare with the unreinforced building at 5 psi. ) You don’t want to be hiding In the attic.

Unreinforced brick is bad. And the third little pig made his house out of brick. The Big Bad Wolf came, and He said “I’ll huff and I’ll puff, and I’ll blow your house down. ” The three pigs laughed (the one who built the brick house and his two less fortunate brothers). What they didn’t realize was that the Big Bad Wolf was bigger and badder than They realized; he was from North Korea, and he was hungry. His nuclear weapon produced 5 psi overpressure. (His aim was bad, but close enough. ) The brick walls have disappeared. Only internal framing is left upright.

Unreinforced brick can survive lighter overpressures (1. 7 psi here)

Rambler and Concrete block construction 5 psi is too much for this sweet little cottage. This is better than unreinforced concrete block construction, which is more typical. This structure survives 5 psi like a commercial government building would.

Better off in a vehicle? Maybe so. 5 psi here. School busses can be death traps. Nuclear weapons don’t make that any less true. This one was rolled, but still it is pretty much intact. Surviving the roll without a seat belt is the problem. Above, the roof is intact but dished in. It looks like the windows are intact(!) If you ducked down, you could survive in this car. And, you can then drive away afterwards! (Good luck getting past the downed trees and utility poles. )

Some more transportation examples Rail car (wooden) at 4, 6 psi Most modern rail cars are steel and would do better. Trucks are survivable at 5 psi but can be blown over like the bus was. You want to take the blast head on.

Airplanes are not designed for this, but don’t do as bad as you’d think. Above, exposed side at 3. 6 psi. Below exposed tail at 2. 4 psi. Nose on is better. Above plane is finnished. The lower one had A good bit of skin and internal damage not visible here. Likely would not fly again. 2 psi is possibly Survivable.

Electric utilities (5 psi) This at. 80 miles At Hiroshima, damage to electric Utilities extended out to 1. 7 miles.

Other utilities: Here’s a bulk LP storage facility (5 psi) The light steel building is blown Away but the piping and tank are OK. No gas leaks. Still viable. Similarly, it takes a lot of overpressure to damage water mains and such.

Bridge damage, Hiroshima and Nagasaki near ground zero “Momnumental” type bridge. Think Market Street Bridge. It’s almost directly under the detonation and takes maximum vertical loading and stays intact and usable. There is some damage to decorative features. This is a trolley bridge, lighter than a normal RR bridge. The lateral component of blast has displaced the bridge, bending the rails. It will have to be rebuilt / replaced.

Machinery Blast damage to heavy machine tools even at 10 psi is relatively minor. But fire damage (which occurred in Japan) was more damaging. The same was true of bombing in Germany. Blast didn’t disrupt production as much. The structures could be replaced much easier than the tools. The use of incindiaries caused much more damage. The masonry wall was Obliterated. The small lathe was knocked over and suffered significant damage. Of course, at 10 psi this is not survivable for a human unless very well sheltered.

Thermal effects: Proportionately worse for big weapons The thermal effects hit before blast. Here we see the facing wall of the house Erupt in smoke from the direct thermal radiation immediately after the fireball (25 cal/cm^2). No open flame though. Imediately after, the blast arrived and Essentially blew out the fire, and the smoke instantly disappeared. The problem, of course, is that the radiation starts fires that continue after the blast. The fires are then be fed by debris from the blast and become dangerous.

Thermal effects Open windows admit thermal radiation Tree remains unburned!

Thermal effects as a hazard to people Note: photo from CD isn’t satisfactory.

Thermal hazards to people - even through clothing Burns were a problem. Being burned through clothing was not common, but occurred, in some cases following black on white pattern. A surprise: Many cases of Temporary blindness but very little permanent eye damage.