...feels more like it's coming from thousands of people squirming about...

Yeah. We use the energy created by tectonic movements.

Alchemy from Amestris utilizes tectonic energy.

There's something in the way between the alchemist and the tectonic energy.

And with this, alchemists are able to use all the tectonic energy to their liking, something that used to be disrupted by philosopher's stones.