A low altitude detonation or a groundburst will cause a crater to form.
Nuclear detonations that take place near the ground (but not underground) will create a mushroom cloud (this is caused by a Raleigh-Taylor instability).
I have noted that a lower level detonation close to the ground will suck up material into the fireball and create a more pronounced stem.
Many nuclear detonations will create a mushroom cloud (especially near the ground due to material from the ground being sucked up into the vacuum created by the explosion, thus forming a large part of the "stem" of the cloud) and if they are near the ground, will create at least a small crater, but it sounds like you are talking about a groundburst detonation (as opposed to an airburst). These types of explosions carry more radioactive debris from the ground into the air and generate a lot of fallout due to the irradiated debris from the explosion.
surface burstshallow subsurface burstvery low altitude airburstan optimal depth shallow subsurface burst will produce the biggest crater.even conventional explosives produce mushroom clouds, just proportionally smaller with the smaller yield.
the higher something is the more potential energy it has. when you drop it that turns into kinetic energy & u gain more momentum. that creates a bigger impact on what the crater hits.
There is a crater on the moon.
This is known as an impact crater. Please see the related link.
A nuclear detination
Surface burst
A shallow subsurface burst.
Surface Burst
surface burst
Surface burst
Any type of nuclear explosion will have this effect.
Surface burts
Surface
Surface Burst
Surface burst
High yield shallow subsurface.