Surface Explosions: Effects and Radius

There's already a page for explosion radius, but only for airburst and only counting 20 psi explosion radius, this one is for surface explosions with different values for different effects.

Sources:

NOTE: In order to use any equation or value of reference used in this blog the explosion needs to happen in flat surface, not necesary horizontal, whose atmospheric and gravitational conditions are the same or pretty similar to Earth's. Equation should neither be used for fire or heat based Area of Effects attacks that carries almost no pressure or not pressure at all, that kind of events qualify as combustions and should not use the equation mentioned in this blog.

Equations could be applicable to any omnidirectional shockwave that cause the corresponding effect, but one needs to account the percentage relationship between heat and overpressure in explosions, value that is at the moment not known.

Of Overpressure Values[]

Value in psi	Value in kPa	Effects in Objects	Equation W =
0.15	1	Minimal to shatter window glass	R^311.384110^(-9)
0.45	3	Violant fragmentation of window glass	R^399.431410^(-9)
1.8	12	Minimal for failure of concrete bricks (not total destruction). Destruction of wooden doors and windows	R^31.4110^(-6)
4	27	Minimal for rupture and failure of steel	R^36.05810^(-6)
6	40	Complete destruction of wood made buildings. Minimal for damage to reinforced concrete. Violent damage to steel structures	R^311.823810^(-6)
9	62	Total destruction of most buildings, severe damage to reinforced concrete	R^324.09710^(-6)
20	134	Severe damage and demolition of heavy reinforced concrete buildings	R^380.368410^(-6)

NOTE: The variables of the equation: W and R are measured in tons of tnt and meters(m) respectively. Values are not exact convertions, as they are rounded.

In order to use any of these equations the explosion has to cause the same effects written above; for example, an explosion that was able to destroy the doors and windows of a house with left everything with only superficial damage or not damage at all means that at the distance of the farthest door/windows the explosion had an overpressure of 1.8 psi, and the yield should be calculated based in that value.

Equally, if an explosion fails to destroy an object within its Area of Effect, that means that the overpressure shouldn't be higher than the overpessure needed to destroy that object at that point, even if the explosion expand further. For example, a explosion that expanded up to a radius of R failed to destroy a wooden structure located ar R - d distance from the origin of the explosion means that, at the distance R - d, the explosion couldn't have carried more than an overpressure of 6 psi.

Explosion Radius Estimations[]

The following radius were obtained from the 20 psi overpressure explosions, value that cause 99% of fatalities (via barotrauma) and severe destruction of reinforced concrete structures.

AP level	Low-End Radius (m)	High-End Radius (m)
Room level	4	<14.6
Building level	14.6	<29.2
Large Building level	29.2	<51.53
City Block level	51.53	<107.55
Multi-City Block level	107.55	<231.72
Small Town level	231.72	<416.34
Town level	416.34	<1075.57
Large Town level	1075.57	<2317.24
Small City level	2317.24	<4279.75
City level	4279.75	<10755.69
Mountain level	10755.69	<23172.43
Large Mountain level	23172.43	<37681.46
Island level	37681.46	<107556.9
Large Island level	107556.9	<231724.29
Small Country level	231724.29	<443272.62
Country level	443272.62	<1068350
Large Country level	1068350	<2100478
Continent level	2100478	<3807174

NOTE: In order to apply these values the explosion have to cover the requeriments for 20 psi overpressure in the point of the calculated distance.