The following can infer about the relationship between fault line and plate boundaries:
The Earth's skin is separated into a dozen of tectonic plates. Plate boundaries are always faults, but not all faults are plate boundaries. The plate displacement relative to one another distorts the crust in the boundary area producing earthquake fault structures. The interior of the plates also includes significant faults and fault networks.
As the plates pass the mechanical energy is retained, in the similar way that energy is retained by a stretched spring. A accumulation of force or stress throughout the fault is correlated with the damage. Meanwhile, frictional force holds the fault together.