system
Given the following post, respond as if you're commenting on Reddit:
human
[ATLA/Korra] Does Earthbending decompress/compress rocks or leave voids underground?

I am an earthbender and I do a common move which makes a rock pillar come up. Does this mean that there is a void left somewhere several feet underground beneath the rock I've raised up. Is it a vacuum; or is it filled with air? Does the suction make the rock want to slide back into place. Or is the rock being decompressed. IIRC in the finale of ATLA we see Aang compress boulders into smaller rocks, presumably without altering their overall mass meaning the rocks were made of super-compressed material, so theoretically rock could be decompressed and made to have a more porus or lightweight molecular/material structure. I know there are other in-universe explanations as to why bending doesnt kill people but lightweight spongy pumice like rocks being earthbent could be part of that explanations.
gpt
One possibility, kind of a middle ground between the two theories: maybe the extra rock molecules are taken from a larger surrounding area? Rather than the moved rock being, say, half as dense as normal, instead all the connected rocks within 30 feet or so become slightly denser.

That being said, the idea of lightweight rocks would certainly explain how people are able to get hit by earthbender attacks and not die instantly.