Okay let's start from the beginning.  An Act of God is a term used in the insurance world to signify natural disasters.  And you are correct in your back door conclusion here that natural disasters are generally excluded from coverage under insurance policies, which is generally why you see the Federal Government jump in with disaster aid.  Without being able to read the policy and paperwork you refer to I am fairly certain that IF there was an earthquake and that caused damage to the garage and then to the condos above, the earthquake would be considered the origin here. The structural soundness of the garage may not have an bearing in this set of facts.  Good luck.