While some may see it as "superhuman strength", this technique is actually an application of medical ninjutsu, that demands the ability to concentrate, along with minute chakra control.
An immense amount of chakra is kneaded inside the body, and a moment later all of it it is gathered into the fist. That chakra is then released into the target, which does a great amount of damage. With the damage done dependent on the amount of chakra used, it is also possible for a skilled shinobi to amass it in their fingertip.
When the ground is hit it is pulverised into many pieces by the excess shock, which are then scattered like flower petals, giving rise to the name "Cherry Blossom Impact".