Mt Kaala in Google Earth
Replica of Mt Kaala in CAD
This is the calculation of a feat Forum Spacebattles pointed out.
"A2 survives a point-blank nuclear-grade detonation. From Anemone's records of the event in the game, this blast actually levels the entire mountain they're in."
The mountain in question is Mt Ka’ala.
First we need to get the volume of the mountain.
According to Wikipedia the mountain has a height of 1,227 m. According to Britannica the plateau at the summit is 1.6 km across. I have measured additional distances using Google Earth.
Now that I have all numbers I need, I use them to recreate the structur of Mt. Kaala using a CAD program. The green part is the actual Mt. Kaala which is used for this calculation, the white part is Mt. Kalena and was needed to get the shape right.
Then I use said program to calculate the approximate volume of Mt. Kaala.
Volume Mt. Kaala: 4.938705 km³ = 4.938705 E15 cm³
Now we can continue with the calculation of the energy necessary to flatten this mountain.
6 j/cc (Fragmentation of Concrete)
E = 6 * 4.938705 E15 = 2.963223 E16 J (7-B, City)
17 j/cc (Violent Fragmentation of Concrete)
E = 17 * 4.938705 E15 = 8.3957985 E16 J (7-B, City)
40 j/cc (Pulvarization of Concrete)
E = 40 * 4.938705 E15 = 1.975482 E17 J (7-B, City)
The mountains of Hawaii are not made out of concrete however. This page states that Hawaii consists mostly of basalt. Basalt is not only heavier than concrete it’s also much much harder.
Concrete 2400 kg/m³ (See here)
Basalt 2960 kg/m³ (See here)
=> 1.23 times heavier
Concrete: 20 N/mm² (Average compressive strength of concrete, see here or here)
Basalt: 200 N/mm² (Average compressive strength of basalt, see here or here)
=> 10 times harder
Utilizing this values we get:
2.963223 E16 * 1.23 * 10 = 3.64476429 E17 (7-B, City+) – Low End
8.3957985 E16 * 1.23 * 10 = 1.0326832155 E18 (7-A, Mountain) – Most Likely
1.975482 E17 * 1.23 * 10 = 2.42984286 E18 (7-A, Mountain) – High End
Using shear strength instead of compressive strength the results would be even higher.
Concrete: 2 MPa (See here)
Basalt: 20-60 MPa (See here)
==> 10 to 30 times harder, using the average of this gets the following result
2.963223 E16 * 1.23 * 20 = 7.28952858 E17 (7-A, Mountain) – Low End
8.3957985 E16 * 1.23 * 20 = 2.065366431 E18 (7-A, Mountain) – Most Likely
1.975482 E17 * 1.23 * 20 = 4.85968572 E18 (High 7-A, Large Mountain) – High End