Types of Explosions and How to Calculate Them

***A) INTRODUCTION***

When we are in front of a feat that involves an explosion it could be difficult to calculate how strong it is or how much energy is needed to recreat it. There are several methods to do it, but it will ultimately depend on the type of the explosion itself.

***B) CLASSIFICATION***

1. Physical: When it is caused by the sudden combustion of a real and known material (e.g.: the gas tank of a car explodes).
2. Metaphysical: When it is caused by the release of energy via magic, Chi or other non-real methods.

***C) CALCULATION METHODS***

Now that we divided all the possible explosion feats in those two categories, we have to see how to calculate them in each case.

* Physical knowing the fuel: The most exact way to calculate it is by using the energy density of that material and multiplying ti by the amount fuel that had combusted (either liters or kilograms).
* Metaphysical knowing the volume destroyed: In case we have to calculate a metaphysical explosion, we'll calculate the energy needed to destroy the volume like it did and use it as a low ball.

If we don't have any of that information required for the two methods from above or the volume destroyed is simply to difficult to be calculated precisely, we should use the formula for the yield based on the blast radius (and its variations depending on whether it's nuclear or not).

We also have to take into account where the explosion took place: if it is a ground explosion what we are calculating, we have to multiply the resulting value for the energy by two.

Note that the formula we use to get the yield in fuction of the blast radius was calculated by using a ground explosion, so (in the case we have to use that formula to calculate the explosion feat) the result will not be changed unless it's an aerial explosion, for which we shoul divide the result by two.

***D) APPLICATIONS TO CALCULATIONS***

Once that we are able to know how powerful an explosion is using different methods, one could want to use those results to scale the endurance of a character that receives the blast, but they would have to follow some rules in order to do it.

The durability can be directly scaled from the explosion without any changes if:

* The explosion occurs at the character's point-blank range.
* It's directly stated that the explosion doesn't lose energy in function of the radius (in other words, the energy is the same for every point of the blast zone).

If none of these conditions meet, we have to calculate the energy per square meter that the blast has at the point the character is and then multiply it by the taget's surface area. In other words, if the explosion expands with a sphere-like shape (which is always the case even though it takes place on the ground, since it is also expanding through it unless it's directly stated otherwise), the area is equal to

4
π

r
2

{\displaystyle 4\pi r^2}

, where the radius would be the distance from the epicenter to the character, then we would just have to multiply the result by the surface area of the target and we will know how much energy did it take from the explosion.

Note that both of this situations can only be applied if the character is within the blast radius, if he is aways from it neither the explosion's yield (for the case where the energy can be directly used) nor the formula explained above will work. Thus, we should use the formula for overpressure.

***E) REFERENCES***

* Energy Education. (n.d.). Energy density. https://acortar.link/N7QO1q
* Bubbico, R. & Mazzarotta, B. (2013). Analysis and Comparison of Calculation Methods for Physical Explosions of Compressed Gases. *The Italian Association of Chemical Engineering*. https://www.aidic.it/cet/13/32/023.pdf
* Myk 25. (2024, January 19). Yield of an Explosion Based on Its Radius (Demonstration). *Physics Fiction Wiki*. Yield of an Explosion Based on Its Radius (Demonstration)