Where any nonconforming building or structure, or building that is nonconforming because of use, has been destroyed or damaged by fire, explosion, act of God, or of any public enemy or the like, to the extent of 50% or more of the fair market value of the whole building or structure at the time of the destruction, it shall be presumed to be totally destroyed, and any building, structure or use thereon shall thereafter conform to all the requirements, terms and conditions of this Ordinance.