system
Given the following post, respond as if you're commenting on Reddit:
human
[Marvel 616] Would Avalanche's powers directly affect Ben Grimm or Sandman?
gpt
Ben Grimm may have rock like skin but Avalanche's seismic waves have not been seen to be at a sufficiently high level to seriously hurt him. Ben can tank a hit from the Hulk and while Avalanche is a serious local threat and can crumble some stone, but he's not going to do nearly enough damage to hurt the Thing. 

Avalanche would certainly mess up the Sandman at first and probably dissolve his shape and make him fall to bits, but that is no problem to the Sandman. He'll simply reform and probably once he has been hit a few times he'll work out how to let the seismic waves flow through him. 

So yes, his powers will work on both, but neither will be all that harmed and Ben will probably make a joke about it tickling or something.