How come a nuke doesn't cause a tsunami?

Question

We've all seen the nuclear tests where they blow up the bomb in the ocean, and a crazy amount of water shoots up in the sky. How come these tests don't cause massive tsunamis? Seems to me that they would, but maybe I just don't know enough to understand, which is why I ask, :)

if it's not a large enough force, then how come a big rock falling off into the ocean can cause one?

Answer 1

When a nuke detonates in the middle of the ocean it doesn't throw water out. It instantly vaporizes a huge volume of water. The giant water spray you see is the water rushing INWARDs into the hole created by the explosion. When the water all meets in the center, the larger part of it's energy is disappated slamming against the other wall of water, the excess is used to throw itself into the air.

In a tsunami, a huge amount of force is used to push water in a single direction. It doesn't stop untill it hits something, like a piece of land.

Answer 2

The easy answer is that the energy from even a very large nuclear explosion is much smaller than the energy of a medium sized earthquake. The LARGEST nuke corresponds to a 7.0 magnitude quake. And no nuke of that size was exploded in the ocean. Also, the nuke is done from the middle of the ocean to minimize the resulting wave. A more typical nuke (of size 1 megaton) corresponds to a 6.0 magnitude quake.

In contrast, a meteorite of 1km diameter has an energy corresponding to a 9.4 magnitude earthquake. If you bump the size of the meteorite, to 10km, it becomes a 12.4 magnitude quake, which is about 1000 times larger than the largest ever recorded. Remember that the meteorite hits at a speed of around 20 kilometers *per second*.

Answer 3

It's not a large enough force. The energy that an earthquake generates is many times greater than a nuclear bomb.

Answer 4

a correctly placed nuke could cause a tsunami, but detonated at the surface doesnt produce enough force to displace the water enough to cause a tsunami.

Answer 5

It's a different type of engergy... the difference between slapping your hands underwater and slapping to big paddles together underwater. During the shots at Bikini, Eniwetok and Johnson, they actually were able to measure a wave as far away as Hawaii, but it was very insignificant.

Answer 6

Casue it doesnt move the earth as much as a under sea earth quake does

Answer 7

Not enough water is displaced for that effect.