A recalculation of this calc. Requested by Wrath Of Itachi
First of all, we need to know that all Bijū Bombs used left a crater, with a spherical cap shape. So, the calculation will be crater + mountains vaporized.
According to Spino's blog, the distance the blast covered is equal to the width of all the mountains together, 7 mountains in a row makes the full distance 17967m and according to Wrath Of Itachi, there are 32 mountains, so we need to calc the vaporization of this mountains. That's the radius since the blast is omnidirecional.
Fine, we have everything to calculate the volume. As I said above, I will use the spherical cap shape. Using this calculator, I got 3421500908088.38 m^3 = 3.421500908 e18 cm^3.
In almost all occasions, a Bijū Bomb showed vaporization, I've showed some of them here. So I will use this method.
Energy: 3.421500908e+18×25700 = 8.7932573e+22 Joules or 21 Teratons (Country level)
Cool, that's the explosion only. Now let's calculate the mountains being vaporized. That's easy, the page I've linked above from our wiki says the volume of a mountain is 7.586e14cm³. Vaporizing this, we get 1.949602e+19 Joules, 32 mountains give us 6.2387264e+20 Joules or 149 Gigatons (Large Island level).
- 21 Teratons, Country level