User:JBel/Sandbox

Crater formation process from an above ground explosion
A common misconception is that an above ground explosion cannot produce a crater. What is true is that an above ground explosion produces smaller craters than a ground level explosion, and much smaller than a below ground explosion, mainly because the intervening air is effective in attenuating the shock pressures. In the first instance, the shock from the explosion cracks and pulverises the ground below it, enhancing pathways for high pressure gas to be admitted. In the negative pressure phase of an explosion, the high pressure gas in the ground acts to propel the ground upwards towards the surface. This material continues upwards and is thrown clear of the crater as ejecta.

Quantitative analysis
For explosions occuring at or above ground level, apparent crater volumes are found to be proportional to the energy transmitted into the ground. Consequently, linear dimensions, such as the radius, are related to the 1/3 power of explosive energy. A single constant is used to account for differing ground strengths and explosive type. The energy coupled into the ground falls off exponentially with height, being around 33% at ground level. Thus:

$$r_a = K{(0.33 e^{-dH}E)}^{1/3}$$ where K and d are constants, H is the height above ground of the energy release, and E is the total energy released. &#x0399;&#x03c9;&#x03b1;&#x03c5;&#x03c5;&#x03b7;&#x03c2;