Ground

I’ve been working alot with trying to figure out a way to program this. I want to create ground that can be walked on, if a bomb explodes on it, it should create a small crater which the character can fall into and get stuck in, but still be able to walk on.
So what i need is ground that can be walked on but also can be blown away.

I’m using as2 and i would really appreciate any help!

Thanks