Explosions - Personal experiences?

[ishtat]

I listened to a conversation a day or so ago about individuals experience of an explosion, eventually all parties to the discussion agreed that they did not really know.

We knew that in the movies the sight of an explosion is at the same time or immediately after the bang, however, if one observes a real explosion at say 3000 yards one sees it well before one hears it. I am less certain of this but is it also true that one also feels the ground vibration and pressure wave before hearing the bang?

Now if one is very close to an explosion, on top of it almost, say in a protected vehicle or ground position, would it be possible to see a flash, perhaps feel it but not hear anything at all? I was told years ago by a man whose armoured vehicle was blown up that all he remembered later was a flash and then recovering consciousness in hospital hours later. Was that memory an accurate summary of the event or faulty recollection of the experience?

 

[Ginlover]

Light travels faster than sound

 

[Brutal_One]

Similar with lightning! You see it and depending on how close you hear the thunder some time after. Brutal One

 

[Bramblethorn]

Light travels faster than sound

And sound/vibration travels faster through solid matter than through air, so yes, for a big explosion a long way off you may feel the ground shake before you hear it, but after you see the flash.

 

[jaF0]

I listened to a conversation a day or so ago about individuals experience of an explosion, eventually all parties to the discussion agreed that they did not really know.

We knew that in the movies the sight of an explosion is at the same time or immediately after the bang, however, if one observes a real explosion at say 3000 yards one sees it well before one hears it. I am less certain of this but is it also true that one also feels the ground vibration and pressure wave before hearing the bang?

Now if one is very close to an explosion, on top of it almost, say in a protected vehicle or ground position, would it be possible to see a flash, perhaps feel it but not hear anything at all? I was told years ago by a man whose armoured vehicle was blown up that all he remembered later was a flash and then recovering consciousness in hospital hours later. Was that memory an accurate summary of the event or faulty recollection of the experience?

Look up the video of explosion of the PEPCON plant, located in Henderson, Nevada.

Can't say on the too-close-for-me one. I'm guessing the shock shunted hearing.

 

[SamScribble]

I have been there. As far as I can remember, there was bright light. And then there was the sound. And my ears stopped working. It was not pleasant.

 

[oggbashan]

If the flash, bang and shockwave arrive at the same time?

It was too fucking close!

 

[Kumquatqueen]

If you're in a building next door to the one blowing up, or down the road, then you might see a change in light out the window or hear a sort of shift and a burst above in the general background rumble, but the force would be what you notice. Rather like a small earthquake.

Don't know about other types of explosion than IRA bombs in London.

 

[Voboy]

I spent some time in my youth calling artillery fire. The explosion of an 81mm mortar or a 105-mm howitzer can't be felt from a surprisingly short distance away, and can't be heard from just a bit farther. You see the flash prior to the rumble, and a rumble is what it sounds like. Like thunder. As ogg says, if you can feel it, it's far too close.

I've been on the receiving end of indirect fire that impacted some 400 meters away, and I could not feel it. Those were 82mm mortars. Again, like thunder.

The sound travels at about 350m/sec, so you can count and multiply to establish range. Fun fact.

I've blown demo and grenades as well; with intervening cover, those are surprisingly quiet as well.

 

[oggbashan]

The sound travels at about 350m/sec, so you can count and multiply to establish range. Fun fact.

...

On the Western Front during the First World War, both sides used widely-spaced sound detecting devices to triangulate the position of a gun firing at them. That information was used for accurate counter-battery fire.

A large mortar shell landing less than ten yards from a slit trench meant instant flash, bang, and shock wave damaging the trench walls. I didn't enjoy that.

 

[jaF0]

On the Western Front during the First World War, both sides used widely-spaced sound detecting devices to triangulate the position of a gun firing at them. That information was used for accurate counter-battery fire.

A large mortar shell landing less than ten yards from a slit trench meant instant flash, bang, and shock wave damaging the trench walls. I didn't enjoy that.

There are no remaining WWI vets:

https://en.wikipedia.org/wiki/List_of_last_World_War_I_veterans_by_country

 

[LupusDei]

I live bit less than two miles from an active quarry, basically on top of the same (dolomite) rock formation being mined. One of the operation modes they use involves explosives, an array of relatively small distributed charges in boreholes. Of course, the explosion itself can't be seen as it's behind a thick forest below the surface ground level, but it can usually be heard, not unlike a distant thunder. Not always, I quite often hear the warning bleeps leading in and out without hearing the explosion itself. And that said, some jet aircraft exiting clouds overhead can be launder.

There's little to no noticeable ground vibrations caused by the explosion itself either, but there sometimes are tremors arriving after the sound -- I believe caused by the resulting landslide, not explosives by themselves (think about controlled demolition of a low rise appartment block, only in this case it's all solid stone just toppling over away from the remaining wall).

 

[oggbashan]

Across the sea from my house is the Army ordnance disposal depot at Shoeburyness. Several times a week they explode time-expired ordnance there.

Usually, we feel the shockwaves rocking the house before we hear the explosion. The strength of the shockwave depends on the sea conditions. A rough sea? We might hear but not feel the explosions. A flat calm? The explosions are like small earthquakes. A flat calm, low tide and frosty? The house shakes dramatically and the noise is very loud.

 

[Enchantment_of_Nyx]

I've two occasions to interview people who were present at various distances from the same explosion. In connection with those occasions, I spoke to doctors who treated people injured, psychologists, and fire & explosives experts. Both explosions were caused by the ignition of natural gas. One explosion took place in a house with two people in it. They both survived, but the house had significant structural damage in addition to being burned. The second explosion took place below street level in an urban setting. The explosion destroyed portions of the surrounding buildings. Neither of these explosions was like a bomb going off in terms of intensity, but they were intense enough to cause temporary hearing loss and fling heavy objects.

These are my observations, which were consistent between the two explosions.

People do not remember things accurately. The closer and more traumatic the experience, the less accurate the recollection is likely to be. They will remember things out of sequence or things that could not possibly have happened at all. It is a series of impressions and interpretations of impressions, but the impressions are so vivid to the witnesses that they have a strong sense of having seen these things - even the ones that did not and could not have happened.

Two people standing right next to each other will experience the event differently and have different recollections. The flash, sound, and shock wave of the explosion might be remembered in any order, and some elements may not be remembered at all.

The further from the explosion a person was, the more closely their recollection comported with no facts - usually. There are major exceptions, especially among those who tend to be dramatic.

Sequence is the most vulnerable aspect of memory, probably because things happen almost simultaneously and are part of the same emotional event.

What I came away with was that people's recollections were genuine reflections of how they experienced it, but not reliably accurate. They should be viewed as highly subjective.

If your character's injuries included severe burns, dilaudid would be administered in the hospital. In the dosage used for burn victims, especially those in induced comas, dilaudid has an amnesiac affect. Once they wake up, they'll have dreamlike impressions that are unreliable, or no memory at all.

Objectively, in the scenario you pose, being right on top of the explosion, the light and sound would be experienced simultaneously. They occur together. At a distance, they can be experienced separately because there is a different interval of delay as the light waves and sound waves travel. When you're right on top of it, there's not enough distance for the delay to be observable.

The question of whether somebody could be unable to hear the explosion depends a lot on what you count as "hearing." The eardrum and the organs of the inner ear would have vibrated. The auditory nerves would have picked up on those signals. Whether the brain every processed the signals to complete "hearing," is a question I don't know the answer to. I suspect that it did, because it happens too quickly to be overwhelmed. Failure to properly create a memory of the sound that was heard seems more likely to me.

From the standpoint of the story, I think you could ask yourself whether you care about objective reality or the character's subjective experience. Of course, since it's fiction, you could make those two things one and the same. If you want to play up the confusion after an explosion and you have multiple characters present, you could use differing recollections. I think you've got lots of wiggle room.

 

[NotWise]

Don't the vast majority of us have experience with explosions? I mean like fireworks. The flash precedes the bang, and the sound fades quickly with distance.

If you're close enough to feel a ground movement, then the initial arrival should arrive before the sound. The speed of sound in air is 343 m/s. Seismic p-waves moving in soil might travel 1000 m/s, but several times that in solid rock. Other kinds of waves travel more slowly.

 

[davion2308]

Demo experience here

There's a thing called acoustic shadow where you may have an explosion happen where you can easily see it but due to the topograpy of the area, the sound wave doesn't come in nearly as strong. You might see a massive BOOM but you only hear a pop.

For the most part, depending on how big the boom is, you will see the explosion and you can see the shockwave, which is the compressed air and the noise of it, coming at you. It helps to be in dusty, dry regions for this because the shock wave kicks up debris and loose dirt. It looks like a thin white film that blossoms out in all directions if you're looking at it from altitude. If you're on level ground or, preferably, in a bunker or a trench, you'll see a wall like rain come at you and then "BOOM."

But if there are a series of rolling hills, the way the sound may travel, the noise will drop off substantially before it gets to your ears. The terrain has to be 'perfectly' set up for this so it's tough to create in reality.

It does happen. I've seen it.

 

[jaF0]

This is all why I suggested the PEPCON video. Most of what is being discussed can clearly be seen in motion. You can see the shockwave approaching the camera.

 

[Zeb_Carter]

And most explosions of military grade don't have a giant fireball. There is a visual of what ever is exploding, then the boom and shock wave.

Go watch a Mythbusters explosion. They do it in slow motion so you can see what is happening. You see the explosion, then you see the shock wave traveling through the air and you hear the boom.

Only explosion of chemical plants an anything dealing with natural gas or petroleum products produce a fireball. Oh and Hollywood special effects.

And yeah, I have been around a few. Mostly the hand grenade type where you hear the shrapnel whizzing over you before you hear the bang. You usually don't see them explode. I you did, you would probably be dead before you heard the bang.

 

[oggbashan]

You get a great flame from a battleship's large guns:

https://youtu.be/40YNZ2kbT50

https://youtu.be/KB4kdeDjz38 (3.44 onwards)

 

[gunhilltrain]

I listened to a conversation a day or so ago about individuals experience of an explosion, eventually all parties to the discussion agreed that they did not really know.

We knew that in the movies the sight of an explosion is at the same time or immediately after the bang, however, if one observes a real explosion at say 3000 yards one sees it well before one hears it. I am less certain of this but is it also true that one also feels the ground vibration and pressure wave before hearing the bang?

Now if one is very close to an explosion, on top of it almost, say in a protected vehicle or ground position, would it be possible to see a flash, perhaps feel it but not hear anything at all? I was told years ago by a man whose armoured vehicle was blown up that all he remembered later was a flash and then recovering consciousness in hospital hours later. Was that memory an accurate summary of the event or faulty recollection of the experience?

Just curious: are you going to use this in a story? Feel free to use these.

An incident from when I was a kid: a mob-connected guy in my neighborhood got into his car and set off a bomb when he switched on the ignition. He survived. We could easily hear it and I think feel it although this was up and over on the next street. A detail I remember: later I saw that the windows of the adjacent apartment building had been blown out. People were inside watching TV. I guess whatever was on was on was more interesting than what was happening outside.

One evening in 1982, I think, I was in my apartment in Brooklyn. All of the windows started shaking in their frames. At first we thought it might be an earthquake, although those are rare in New York.

It turned out that a gas tank had exploded in Newark, NJ, probably twelve miles away.

The takeaway: the sound and shock waves can travel a long way.

 

[oggbashan]

...

The takeaway: the sound and shock waves can travel a long way.

The opening barrages for the Battle of Passchendaele could be heard in London - ninety miles away.


The mines exploded under Vimy ridge could be heard two hundred miles away.

 

[jaF0]

One evening in 1982, I think, I was in my apartment in Brooklyn. All of the windows started shaking in their frames. At first we thought it might be an earthquake, although those are rare in New York.

It turned out that a gas tank had exploded in Newark, NJ, probably twelve miles away.

January '83: https://en.wikipedia.org/wiki/1983_Newark_explosion

" The blast was felt up to 100 miles (160 km) away, in areas including White Plains, New York, and Southport, Connecticut."

 

[Enchantment_of_Nyx]

January '83: https://en.wikipedia.org/wiki/1983_Newark_explosion

" The blast was felt up to 100 miles (160 km) away, in areas including White Plains, New York, and Southport, Connecticut."

Flames 1,000 feet high! That's incredible. It's amazing there was only one fatality and few major injuries.

 

[KeithD]

I was near a bombing at Damascus Gate in Jerusalem one morning and near another one in the afternoon in Nicosia Cyprus, when the Commerce Ministry down the street from my house was bombed as we were returning home from Israel. I wasn't looking in that direction either time, and all I can remember experiencing when the bombs went off was the sound of them.

 

[TxRad]

Proximity is key. To close and there is no memory. To far away and it's not memorable. Close enough to catch shrapnel is a memory forever.