When a lot of built-up stress is suddenly released, existing faults can move in unpredictable ways, resulting in major earthquakes. But plate movement doesn't necessarily cause earthquakes, or it may only create underground faults, with no ruptures appearing on the surface.
而一旦板塊相互推擠產生夠大的應力時，既有的斷層也可能產生不穩定滑動，因而引發大地震。