GFCI outlet consistently trips in garage
A wiring failure due to slab movement is unlikely unless the wiring is in conduit in or under the slab. Is it?

Put in a new GFCI receptacle and see if it works. If a new one doesn't work, you'll have a replacement GFCI on hand for a future failure. 

Or if want to go sleuthing, turn off the breaker to this GFCI receptacle, remove the cover, remove the two screws securing the receptacle and pull the receptacle out without disconnecting it. Turn the breaker back on and see if you can reset the receptacle.

If it will reset, then this indicates that the wires are folded in the box in a way that is allowing a ground to contact the hot or a hot to contact the box (if box is metal).

If you have a standard receptacle lying around, put it in place of the GFCI receptacle see if it works. Test it with a 3-prong circuit tester.

My guess is the GFCI receptacle is bad. To test it put it in place of a standard receptacle somewhere in your house that is not protected by a GFCI receptacle or breaker.