You would know better if that is possible Mr Musk.

I think it is.

I think that, if you make the digging machine gigantic, and so does the hole itself,

it is prone to collapse.

 

As the dirt to the sides of the diameter has far more susceptibility to gravity.

 

BUT. If you can create shields as you go about digging, incrementally,

wouldn't that be a safe way to create tunnels?