How does a blast wave kill you?

[Michael Lewis]

I was reading Pegasus Bridge and it gave a report where a group of Brits were killed by the blast wave of a shell. The ghastly thing about it was that they were playing cards in a foxhole and were basically frozen in that position. My cousin who's in the army said that a .50 machine gun can kill you if it even hits a foot away from your head from the shock wave.

How does the blast wave kill?


Thanks,

Michael

[Tegyrius]

As I understand the theory, an explosion has three different ways to kill you. I'm probably not using the proper medical terminology here, though.

The first is penetrating or blunt trauma from debris propelled by the explosion, even if the warhead or device isn't specifically designed for fragmentation (though this falls under 2.2 and Reflex's fragmentation damage, not blast damage).

The second is the kinetic effects of the shock wave compressing soft tissue, particularly in the torso's vital organs, which can tear that tissue and/or the embedded blood vessels. This effect may include a secondary possibility of brain or organ damage caused by compression-induced spikes in fluid pressure in the circulatory system.

The third is acceleration of the body (i.e. being propelled away from the explosion's epicenter) causing impact damage to the brain as it bounces around the inside of the skull, just like any other source of cranial acceleration trauma.

Also, I call shenanigans on the .50 caliber rumor until I see scientific proof otherwise. Yeah, it'll kill you if it hits a foot away from your head - if that "foot away" puts the impact in your torso. Hitting scenery a foot away? I don't think it carries enough energy to generate that sort of overpressure in air.

- C.

[stg58fal]

Pressure. But a .50 isn't going to do it. The muzzle blast is impressive, but the projectile isn't big enough to do all the things it's said to do (tear your arm off if it comes within a foot of you, for example).

[Tegyrius]

Pressure. But a .50 isn't going to do it. The muzzle blast is impressive, but the projectile isn't big enough to do all the things it's said to do (tear your arm off if it comes within a foot of you, for example).

Yup. If that were the case, accuracy wouldn't matter with an M82. ;)

- C.

[stg58fal]

debris propelled by the explosion

the kinetic effects of the shock wave compressing soft tissue

acceleration of the body

He said it better than I did. I was only thinking of the example Michael gave, i.e., how the Brits in that hole got aced by the explosion.

[HorseSoldier]

Yeah, mythology on the fifty cal. There is a lot of that, owing I think to the 50 cal being about the biggest, most powerful weapon an individual can direct lay and open up on people with.

The pressure wave from a blast is pretty under appreciated in Hollywood, etc, but can be absolutely devastating as noted up thread.

[Grimace]

Having been on the receiving end of blast overpressure, I can say a couple things with assurity.

First, the blast somehow manages to daze/stun you temporarily. I'm guessing it has something to do with what it does to your head. I don't know if it's from the sudden and intense change of air pressure or not. I didn't hit my head against anything, but the helmet I had was blown off my head from the blast.

Second, I felt "funny" for the next five minutes. I was partially protected by a solid object, but half of my torso (and head) was exposed. I felt as though someone had bounced on my chest a couple three or four times. It didn't *hurt* per se, but I felt as though my heart was beating differently than it normally does. My breathing was also slightly disrupted. I recovered my breath much, much faster than I was able to get rid of the "funny" feeling in my chest.

I could imagine if you were closer to a big enough concussive blast, it could probably have an adverse effect on your heart, and actually cause it to stop. I don't know about freezing your body, but I could see a blast killing a person by stopping their heart.

To my knowledge there are basically three methods, as Tegyrius mentioned, but they're slightly different than what he mentioned. Trauma from impact of the directly propelled object or from flying debris initiated by the object, concussive damage that damages the brain or internal organs, and shock caused by either trauma or blood loss. Considering that some people die from "blood loss" when they lose such a small portion of their blood, but go into shock from the blood loss, shock plays a fairly important and major role in causing death.

[Tegyrius]

Having been on the receiving end of blast overpressure, I can say a couple things with assurity.

First, the blast somehow manages to daze/stun you temporarily. I'm guessing it has something to do with what it does to your head. I don't know if it's from the sudden and intense change of air pressure or not. I didn't hit my head against anything, but the helmet I had was blown off my head from the blast.

Could have been concussion from your brain sloshing back and forth inside the skull as your head bounced back, could have been overpressure effects on your ears. Anatomy & physiology isn't my strong suit but I'd look to those first as possible causes.

I could imagine if you were closer to a big enough concussive blast, it could probably have an adverse effect on your heart, and actually cause it to stop. I don't know about freezing your body, but I could see a blast killing a person by stopping their heart.

Yeah, I'd expect the body to fall over in such a case. I mean... blam, dead, yeah, but rigor mortis ain't that fast.

To my knowledge there are basically three methods, as Tegyrius mentioned, but they're slightly different than what he mentioned. Trauma from impact of the directly propelled object or from flying debris initiated by the object, concussive damage that damages the brain or internal organs, and shock caused by either trauma or blood loss. Considering that some people die from "blood loss" when they lose such a small portion of their blood, but go into shock from the blood loss, shock plays a fairly important and major role in causing death.

Yep. I can see the shock and blood loss (whether it's external or internal bleeding) coming from the tissue damage I mentioned. Also, I do think the compression wave damage to organs and the deceleration trauma from being flung and hitting the ground/scenery are technically separate mechanisms of injury, though they may well have the same net effect. Still, it looks like we're mostly in alignment.

I will caveat (and should have done so earlier) that I'm speaking academically, not from personal experience. This topic came up in a medical course I took last summer, and I went back through my notes and the class handouts to verify my recollections, but I have neither firsthand experience nor extensive formal training with blast injuries. YMMV.

- C.

[raketenjagdpanzer]

A friend of a friend was in an MRAP that hit a mine on Route Irish outside of Baghdad. No injuries, nothing. Started having serious emotional problems that were ascribed to PTSD, so they gave him a fistful of xanax to take on a daily basis and a desk job (still in country) and he was still having issues. Got rotated home, VA kept sending him for "talking therapy" and more and more and stronger and stronger antidepressants until finally he went to a civilian hospital and got the full MRI the VA insisted he didn't need and found out lo and behold his pineal gland had gotten detached. It was still there and still connected but it had been pushed around and damaged while nothing else in his skull had been. Left him prone to fits of rage, impotent...just a fucking mess.

So...that's how. Just another mm or so of movement would've left him dead.

[TrailerParkJawa]

A friend of a friend was in an MRAP that hit a mine on Route Irish outside of Baghdad. No injuries, nothing. Started having serious emotional problems that were ascribed to PTSD, so they gave him a fistful of xanax to take on a daily basis and a desk job (still in country) and he was still having issues. Got rotated home, VA kept sending him for "talking therapy" and more and more and stronger and stronger antidepressants until finally he went to a civilian hospital and got the full MRI the VA insisted he didn't need and found out lo and behold his pineal gland had gotten detached. It was still there and still connected but it had been pushed around and damaged while nothing else in his skull had been. Left him prone to fits of rage, impotent...just a fucking mess.

So...that's how. Just another mm or so of movement would've left him dead.

I think it's sad that he didn't get the proper care or check up he needed from the VA.

[Targan]

I was a little bit too close to a few explosions back when I was a shotfirer (aka powder monkey). I know exactly what Grimace says about the "funny feeling" you get in your chest. I suspect he's talking about an explosion that occurred near him in actual combat, and I'll wager that he was somewhat closer to his explosions than I was to mine.

During my explosives training we let off a couple of fairly big ANFO explosions that were detonated virtually on the surface on flat, dirt ground. Mainly to show us what a bigger explosion looks and feels like. Upwards of 50 or 60 kilos, with a half a dozen sticks of Powergel to ensure a good initial detonation (I've seen much more ANFO go up but only with delayed detonations, the individual charges were smaller). We were crouched behind a low berm probably half a football field distant and you could clearly see the shock wave spread out from the epicentre. You feel the "crumph" right through your body. The first couple of times it creeps you out.

[Graebarde]

I think it's sad that he didn't get the proper care or check up he needed from the VA.

However the VA was the SECOND ones that failed, the military medical facilities should have checked him out too. Wonder how many other PTSD victims are of a similar nature?

[WallShadow]

---snip---You feel the "crumph" right through your body. The first couple of times it creeps you out.
Like being in close proximity to a bunch of bagpipers, only much less damaging!:D
NOTE: I really do love the pipes, but I couldn't resist the free shot.

[Medic]

As one of the resident medics, I believe, I could clarify the effects of pressure waves on people.

Now, explosion is a sudden, rapid combustion. It causes heat and a shockwave, both of which have potential to kill.

Heat causes burns and combusts flammable materials. Clothing protects from the worst of it, but if it is not fire resistant, it might combust. Especially synthetic materials often have a nasty tendency to melt when subjected to great heat.

The shockwave is caused by the overpressure, caused by the air expanding due to the explosion. This has several results.

Depending on the force of the explosion, the shockwave sends things flying. The only problem is, it also leaves a vacuum in the ground zero, and should the explosion be powerful enough, the vacuum takes up to a couple of seconds to fill. This means, with bigger explosions, you need to duck not once but twice, as all the stuff that flew off with the shockwave has the nasty tendency of coming back shortly. Best idea is to sit in a foxhole and keep your head down.

Human body has about 60-70% of water and water is a relatively good conductor for a shockwave. While the bones form a rigid case around the lungs, but it isn't enough to stop the shockwave. While the overpressure from the shockwave simply compresses the gases inside the sinuses of the body, the rapid decompression after the shockwave causes the gases to expand so rapidly, the tissues can not compensate. Particularly vulnerable to damage from this kind of decompression is the bowel, filled with fecal matter and gas. It has been documented that people subjected to explosion shockwaves have had extensive damage to their bowels, up to several meters of bowel splitting open inside the abdominal cavity, which leads to a very nasty infection.

Overpressure in turn can cause damage to ears as the tympanic membrane , though flexible, can stand only up to so much. And it is not only the tympanic membranes in the ears that can be damaged. Hearing works through the tympanic membrane moving two very small and delicate bony structures - the hammer and the anvil, both very vulnerable to damage.

Overpressure also causes (usually small) tears in the lung tissue, due to the pressure differences outside and within the thoracic cavity. Lungs are not the only inthe thoracic cavity, that can be damaged. Heart in itself can be damaged by violent external pressure - for an example the F1 driver, Ayrton Senna, died of cardiac contusion after colliding the track wall in high speed.

In a nutshell, if you encounter someone who has been close to an explosion and that person is bleeding from his ears, it is safe to assume that he has a) perforated eardrums and b) perforated bowel until proved otherwise.

A great deal of injuries in explosions are so called secondary injuries that come not from the debris or the explosion itself but falling over or falling from somewhere. As a rule of fist, falling from higher than your own height is considered to be a high energy injuries.

[Michael Lewis]

Wow. I looked up body cavities. There's quite a lot of them.

[Medic]

I believe, if you put that as a search on the internet, you'd get plenty of porn. :D

Mostly the problem is there if the cavity is either filled with something compressable (bowel) or is in close connection to the outside (ear). Technically opening one's mouth when the shockwave hits might help with the ears, but the bowel - well, just try to keep out of the way of the blast.

[Michael Lewis]

Yeah, I don't think that would be too much fun to game/role-play.

[Medic]

Well, in roleplaying games, you might make a house rule about damage caused by shockwave - if it hits abdomen, make a check against the damage in point. If unsuccessful, you have just received internal damage that requires surgery. If it hits the head, same thing, except that you are deafened (at least for a while).

[Grimace]

I was a little bit too close to a few explosions back when I was a shotfirer (aka powder monkey). I know exactly what Grimace says about the "funny feeling" you get in your chest. I suspect he's talking about an explosion that occurred near him in actual combat, and I'll wager that he was somewhat closer to his explosions than I was to mine.

No, not combat for me. Underground mining and blasting "rounds". Still, the blasts were fairly sizable, and I while I was "technically" at a safe distance, when close to 700 pounds(around 300 kilos)of explosives went off, it still had quite an impressive effect on me. I could only imagine what it would be like being closer to the blast and within range of the flying debris.

[Cpl. Kalkwarf]

Ummm Guys isnt this already taken into effect using the Concussive damage in the rules already.... in an abstract way of coarse.?

[Graebarde]

I was reading Pegasus Bridge and it gave a report where a group of Brits were killed by the blast wave of a shell. The ghastly thing about it was that they were playing cards in a foxhole and were basically frozen in that position. My cousin who's in the army said that a .50 machine gun can kill you if it even hits a foot away from your head from the shock wave.

How does the blast wave kill?


Thanks,

Michael

You know reading this again I KNOW what blast killed those boys. It was the RSM that caught them playing cards and not a shell. The shell story is the coverup to protect the innocent. <grin>

[Targan]

No, not combat for me. Underground mining and blasting "rounds". Still, the blasts were fairly sizable, and I while I was "technically" at a safe distance, when close to 700 pounds(around 300 kilos)of explosives went off, it still had quite an impressive effect on me. I could only imagine what it would be like being closer to the blast and within range of the flying debris.

Ah, underground blasting. I've never done any of that. To be honest I don't think I'd want to. Those 300kg of explosives must have been in smaller rounds on delay, surely? That's a hell of a blast all in one go. Don't get me wrong, here in Australia on the iron ore mines they let off tonnes of the stuff at a time but it's in a ripple, quarter-second or so delays between lines of blast holes.

[Grimace]

300 kg of explosive put into 36 holes, detonated in a series. 0.1 ms up to 20 ms delay. Det cord was used to set off the blasting caps. So when you were a long distance away you could hear "pwump-pwump-pwump-pwump" in rapid succession. When you were the distance I was, into one big PWUMPF!

[James Langham]

Another injury often forgotten is cranial compression, caused (in this case) by a bleed inside the skull putting pressure on the brain. Signs and symptoms may not show for up to 48 hrs after the impact and it can be fatal (the actress Natasha Richardson is a good example). It is the reason that children bring home notes from school saying they have bumped their head. Treatment is removing a section of the skull to allow the swelling to expand outwards and relieve pressure on the brain.

[dragoon500ly]

Came across this description of being under heavy artillery fire…

“The most clichéd but accurate metaphor for the sound of incoming shells in flight is that of an old-fashioned steam express train rushing past a few feet away. Depending on their distance, speed and angle, shells tunneling through the air make slightly different noises, so a heavy barrage weaves itself into a bewildering cacophony of sounds; but the rushing always ends the same way, with a thunderclap detonation. Hollywood’s microphones fail to convey either the sharpness or the loudness of battlefield explosions; and the visual effects normally used to simulate shellfire---with plastic bags of gasoline and aluminum silicate---are equally misleading. In reality the eye usually registers a shell burst as an instantaneous orange-yellow flash inside a dark, leaping fountain of mixed smoke and pulverized earth, sometimes studded and fringed with large pieces of slower-moving debris. The bigger, heavier chunks of earth and stones thrown up by the explosion fall near by first; the smaller debris, blown much higher, comes pattering and clinking down for a considerable time afterwards and over a wider area.”

“The instantaneous pressure wave from the explosion moves outwards at supersonic speed---this is the expanding ring effect seen fleetingly in, for example, aerial footage showing the explosions of sticks of bombs. It is followed after a slight, but appreciable interval by a blast wind---the bulk of hot gases, fragments and ground debris away from the explosion. People in the target area experience the pressure wave as a sharp squeezing sensation in the chest, and its shock is also felt through the ground underfoot; this shuddering of the earth is powerful enough to make those sheltering in trenches fear (justifiably!) that they are about to be buried alive, and those who are lying flat feel themselves being shrugged violently into the air. These sensations are accompanied by stupefying noise and under heavy and persistent fire all the physical senses are overwhelmed. Completely impotent to affect their chances of survival, soldiers find sustained shelling and mortaring the worst ordeal of battle; those experiencing it often become temporarily unhinged, losing all muscular control (including of the bladder and sphincter) and the capacity for any rational thought. These effects are particularly marked among those exposed to shellfire for the first time.”

“In the minority of cases when men suffer a virtually direct hit from artillery, the result is complete destruction of the body. The shell literally destroys the body, leaving, perhaps, a booted foot, a section of the human cranium, a bunch of fingers, a bit of clothing. When a body is blown up, the spinal column---surprisingly resilient---often survives; after a shell has fallen among a group of men, counting the remaining spines is often the only way to determine the number of dead.”

“Most injuries, however, occur further out from the site of the explosion. Blast injuries to the human body are categorized as primary, secondary and tertiary. The first is the direct effect of the pressure wave; the second the effects of fragments and debris carried by the blast wave; the third, the result of the body being thrown through the air and striking the ground or other obstacles.”

“The most obvious sign of primary injury is rupture of the eardrums, which may occur when air pressure rises to anything between 5 and 15 pounds per square inch; men who are killed by blast often appear peacefully asleep apart from the tell-tale bleeding from the ears. The lethal internal damage caused by pressures of 50psi and upwards do not present dramatic outward signs. It is the gas-containing organs which sustain immediate and often fatal damage from the pressure wave; the lungs and occasionally the colon suffer catastrophic injury from the instantaneous compression effect of the blast. Large, blood-filled cavities are formed in the spongy alveoli of the lung, and fatal air embolisms are released into the arterial system; less often, the bowels may rupture, as may the spleen and liver.”

“Secondary injures will be more obviously dramatic. When a shell bursts the steel case breaks up into fragments of all shapes and sizes, from tiny beads to twisted chunks weighing several pounds. These, together with stones, pieces of weapons and equipment, and even large bone fragments from casualties nearer the blast---whirl outwards from the center at different speeds. The effects of being stuck by shell fragments vary as widely as the size and speed of the shards. Sometimes a man is unaware that he has been pierced by a small splinter until somebody points out the bloodstained hole in his clothing. Larger fragments, cart wheeling unevenly through the air edged with jagged blades and hooks, can dismember and disembowel.”

“In many cases the evidence confronting an eyewitness is all too vivid. In others the immediate reaction is one of simple puzzlement: blast and steel can play such extreme games with the human form that the observer does not understand what he is looking at. When some random physical reference point suddenly jerks the whole image into a comprehensible pattern, the shock of recognition may be appalling. The results of massive destruction, the ruined hulk of a torso, the crimson rack of ribs, the glistening entrails, limbs ripped away and scattered, a severed head---have a charnel house squalor that denies all human dignity. On chilly evenings, the warm, gaping body cavities steam visibly, and the opened up bowels gave off the stick of feces.”

Source is “The Last Valley, Dien Bien Phu and the French Defeat in Vietnam”

[pmulcahy11b]

Ummm Guys isnt this already taken into effect using the Concussive damage in the rules already.... in an abstract way of coarse.?

By necessity, T2K (and most other RPGs) oversimplify complex effects to facilitate game play. But yes, that, at its heart, is what causes most of the damage in an explosion: concussion. What's being compressed is air itself, and it can hit someone or something like a freight train. That's concussion. Imagine being slammed against a brick wall suddenly. (Or more like the brick wall being slammed against you.) Another way to look at compression is as overpressure; momentarily, the atmospheric pressure in the shock wave radiating out from the explosion is much higher (depending upon the force of the explosion).

What's worse is that some concussion injuries aren't immediately obvious. It may be weeks or months before someone realizes, "Dale's been acting more and more strange lately."

Here's something not in the rules: Very large explosions, such as from Daisy Cutters or nuclear explosions, can hit you with a concussive blast wave when the air is pushed out from the explosion, and then the air that got displaced suddenly gets sucked back in, fast enough to cause another damaging concussive wave on the way back in!