Trist's Rocket Jump

My understanding is that the skill is referencing the old Quake trick of jumping and firing a rocket underneath yourself to ride the shockwave.

Tristana fires at the ground to propel herself to a target location

So, why does Trist's Rocket Jump cause an explosion at the destination? It can't be from the impact, she's like 5 pounds.

Shouldn't the skill do damage at the origin point instead? I find the current behavior incredibly counter-intuitive.