Problems[]
To quickly get something out of the way, we have no evidence that these mountains are 609 metres. I found nothing even after looking through the Hero Perfection Guide and the manga to get any sense of scale. Even if we did know their heights, there's also no shot of the mountains in full during this scene.
Addressing KGiffoni's calculation.
- The explosion was probably the House of Evolution and not the adjacent mountain, which had its peak blown off. The fact that ONE's original webcomic never has a second mountain but still includes this scene makes me highly confident of this. With that in mind, there's no way this crater is 250 metres in diameter.
Now for Qawsedf234.
- The rubble is not natural rock, it's concrete, and there's no visible rubble from the rocks (barring a few fragments falling from the outer edge of the crater). This suggests the building was fragmented by the blasts, which created a fireballs that vaporized the two mountainsides. Supporting this, you can even see trenches that the ground beyond the House of Evolution was destroyed in a different manner to the building.
Edit: Since some people disagree (plus I really don't care about this anymore), I'll add in some frag, v frag and pulverization ends.
Calculation[]
The House of Evolution is 8 storeys, which can be 30, 32 and 33 metres (I'll use 32). Given how compact it is, 24 metres (3 metres per floor) seems like a good assumption. The explosion and crater were at least equal to the building in size.
For reference, this is an 8-storey building next to a person, while this is most of the crater. So the size seems completely reasonable, if moderately low-balled.
Spherical Cap[]
Crater = 45.72 px / 32 m
Crater Depth = 24.26 px / 16.9798775153 m
Given the second crater's appearance, I think using spherical cap is fine. Unlike that one, this was directly in the mountain's side, and it looks much more hemispherical.
The formula is πh²/3 (3r - h), where h is height, and r is the radius of the sphere
(π * 16.9798775153²)/3 = 301.924060953
(3 * 16) - 16.9798775153 = 31.0201224847
301.924060953 * 31.0201224847 = 9365.72135184 m³
The adjacent crater has the same rough shape and angle, so I think saying it's the same size is fine. However, despite extending over less area, it does seem to have a greater volume due to the conical top.
9365.72135184 * 2 = 18731.4427037 m³
Fragmentation of rock is 8 j/cc
18731442703.7 * 8 = 149851541630 J
V frag is 69 j
18731442703.7 * 69 = 1.2924695e+12 J
Pulverization is 214 j/cc
18731442703.7 * 214 = 4.0085287e+12 J
Vaporization of rock is 25700 j/cc
18731442703.7 * 25700 = 481398077485000 J
Semi-Rectangular Tank[]
As I said before, there's a little trench in the ground beyond the clearing, suggesting only this section was vaporized.
Crater Depth = 185 px / 12.7349081365 m
Section Height = 271 px
I'm aware that it'd be higher, but we can't see how high it is. So this is a low-ball.
2*atan(tan(70/2 deg)*(185/271)) = 51.09573503012 degrees
Using the angular size calculator gets 13.321 m for the vaporized section.
Using half a rectangular tank.
(12.7349081365^2)*π = 390.083527969 m²
509.496852861 * 13.321 = 6787.00757696 m³
Multiplying this by 2 doesn't make sense to me. The second crater, despite having a similar shape, is not rectangular tank.
Fragmentation of rock is 8 j/cc
6787007576.96 * 8 = 54296060615.7 J
V frag is 69 j
6787007576.96 * 69 = 468303522810 J
Pulverization is 214 j/cc
6787007576.96 * 214 = 1.4524196e+12 J
Vaporization of rock is 25700 j/cc
6787007576.96 * 25700 = 1.7442609e+14 J
Final Tally[]
Personally, I do prefer the second shape given the first crater shape we see in this panel. But, the second is definitely something of a spherical cap. Adding the two shapes makes the most sense to me.
Fragmentation[]
Spherical Cap = 35.8153780185 Tons of TNT (City Block level)
Semi-Rectangular Tank = 12.9770699368 Tons of TNT (City Block level)
Combined = 48.7924479553 Tons of TNT (City Block level)
Violent Fragmentation[]
Spherical Cap = 0.30890763541 Kilotons (Multi-City Block level)
Semi-Rectangular Tank = 0.111927228205 Kilotons (Multi-City Block level)
Combined = 0.42083486361 Kilotons (Multi-City Block level)
Pulverization[]
Spherical Cap = 0.958061361996 Kilotons (Multi-City Block level+)
Semi-Rectangular Tank = 0.34713662081 Kilotons (Multi-City Block level)
Combined = 1.30519798 Kilotons (Small Town level)
Vaporization[]
Spherical Cap = 115.056901885 Kilotons (Large Town level)
Semi-Rectangular Tank = 41.6888371721 Kilotons (Town level)
Combined = 156.745739057 Kilotons (Large Town level)