yes,vibration is sound,sound is vibration
i had a long ass argument with a friend about this,the only reason he wouldnt agree with me is cause his teacher told him that it makes no sound,and hes to dumb to think for himself
it may not make harmonical sound since no one(living) is around to interpret it.
but anything else in the woods will know what happened from the vibrations it gave off
jus my 2 scents