# Is it possible to hear a nuclear blast first from the ground, and afterwards through air?

Since a mechanical wave travels faster in the solid, and if you were able to put your ear on the ground, on the same surface that the bomb hit, would you hear the shockwave first from the ground? Does the air in between the soil particles ''absorb'' or ''delay'' the shockwave?
I know that the composition of the soil is not that uniform and that might oblige us to make approximations. I tried making some research on google and couldn't find anything about it. I hope I was clear enough, I'm from Brazil, so my English is not the best.

• Much of the energy released is in the form of photons, which travel faster than sound. There is then a complex interaction of the photons and the medium to consider. Mar 7, 2019 at 13:52
• Since a mechanical wave travels faster in a denser medium This is not true. All other things being equal, a mechanical wave travels more slowly in a denser medium. The speed depends on both density and stiffness.
– user4552
Mar 7, 2019 at 14:42
• Thanks, Ben, I'm going to edit the question. Mar 7, 2019 at 15:18
• Earthquake waves travel at >10x the speed of sound in hard rock en.wikipedia.org/wiki/Seismic_wave Mar 7, 2019 at 16:49
• Do you want to know about actual "shock waves" (i.e. propagating faster than the speed of sound) or just mechanical waves in general?
– JMac
Mar 7, 2019 at 19:25

## 1 Answer

It is possible- in fact, high-speed photographs of atomic bomb blast tests close to the ground clearly show that the sound wave travels faster through the ground than through the air, at least during the first fraction of a second after the bomb explodes. This presented a significant problem for blast photography because this "precursor effect" would kick dust into the lenses of the cameras close to the blast point while they were supposed to be filming the initial phases of the fireball expansion.

Now, as to whether or not you would hear this effect, to be close enough to the blast to do so would also mean you would die.

During the second world war, soldiers near the beach would hear the sound of a cannon (on a distant ship that was firing at a target on the land) emerging from the water before hearing it through the air, because the speed of sound through the water path was quite a bit faster than that through the air.

• A shock wave may be somewhat of a special case, since it specifically involves a supersonic wavefront.
– JMac
Mar 7, 2019 at 19:24
• Related to heartquake bangs, too. Mar 8, 2019 at 9:32
• @Alchimista- "Heartquake bangs"? please explain... -NN Mar 8, 2019 at 18:39