Please excuse me if I make any mistakes, this is my first post here.
If there were giant creatures, ranging anywhere from 20,000 square miles (approx. 30,100 square km) to 100,000 square miles (approx. 160,000 square km) large, that were dormant dozens of miles/km underground and they occasionally shifted an extremity akin to a finger or toe, how would that shifting impact the land above them? Would it cause earthquakes? Or have a different effect? No effect?
I'm just toying with this idea and have no background in geology, so I really don't have a clue how this would work realistically. Even somewhat vague answers would be much appreciated.