It was the end of my first deployment, and we had a certain number of materials that we needed to get rid of — among those materials were several types of explosives. We built a charge (an explosive) that would undoubtedly take care of every last piece of those materials, and we walked back two or three times the calculated necessary safe distance. The remote area in Afghanistan was relatively flat, and though the explosives were tucked behind a small, distant berm, we would have a full view of the explosion and its after-effects.
As it detonated, a blast wave ripped past us, carrying dust with it as it trembled across the Afghan desert. I had seen quite a few explosions before, but most of them were at night, or at least somewhere with limited visibility (among buildings, in the trees, etc). My teeth had been rattled a couple of times before, but this was the first time I had sat in clear view of a very obvious bast wave — almost the type that you would expect to see in a movie.
Of course, it’s not quite as dramatic as the blast wave they added to the original “Star Wars” trilogy with the explosion of the death star, and it was mostly only visible because of the dust it carried, but it was still quite something to see.
The blast waves from a nuclear bomb:
A blast wave is essentially a wave of pressure that pushes outward from the explosive. This is why anyone who has seen a thermobaric grenade go off in a flat field in daytime also knows what a blast wave looks like — the damage from thermobaric grenades is spelled out in its name: heat (thermo) and pressure (baric). That pressure moves out from the thermobaric grenade, careening into anything in its path. If one of those goes off inside a room, for example, those pressure waves pass through human bodies, and they often bounce off of walls and pass through them again — and potentially more times. The overpressure from explosives can be what really damages the human body, and is often the most deadly piece to an explosive. It is also why blast TBIs are so prevalent now that IEDs are a commonly used weapon by Taliban militants in Afghanistan.
Interestingly enough, once a blast wave passes and that pressure has gone outward, it leaves a vacuum inward. This creates a strong wind of negative pressure, essentially pulling things back toward the central source of the explosive. While this isn’t always apparent with the relatively small explosives I have worked with, it can be seen quite clearly with nuclear blasts. Sometimes this vacuum has been known to create winds that greatly exceed the winds of some of the most powerful hurricanes recorded.
Though the blast waves included in the videos below are easy to see, they don’t have to be obviously visible to end someone’s life. Movies have often portrayed the deadly parts of an explosion to either be the shrapnel or the flames (both of which are absolutely dangerous), but what really kills you is the overpressure.
This explosion is similar to the one I previously described:
This video shows what is allegedly two thousand pounds of C4 being used to detonate a bridge.
This bomb dropped in Vietnam quite clearly shows a blast wave:
Just as pressure can move through the air, it can also be seen in water — and of course, it can move underground as well. This is a video of a nuclear bomb being detonated underground:
Blast waves move incredibly fast. Here it looks as if the wave and the explosion happen all at once, but if you look closely you can see the wave travel outward.
This is a VBIED (Vehicle-borne IED).
These rapid changes of pressure can happen anywhere, even in nature. The following is a shock wave on the surface of the sun following a solar flare:
Similarly, this shock wave occurred after the eruption of a volcano:
Featured image courtesy of Wikipedia. Videos from imgur, Reddit and YouTube.