Dont worry about the ground is shaking, that just means trolls. Just build a defendable base that you port to at night. Even if you explore far away, just use a portal to port back to your main base.
You have a few options to make your base nearly impenetrable. The easiest is a moat, 2 sqaures wide and 2 squares deep, they cant pass it, and takes no materials except time, and stamina. Second best is stone you only have to make it one high technically since mobs done jump. The wood fence posts can be knocked down by trolls and gremlins so are really just for a starter base. The very best is a solid ground wall, which is impenetrable, but takes a lot of stone.