Some deformation is permanent, though, and we recognize this in folded rocks and uplifted mountains. The San Andreas fault in the San Francisco Bay Area, and portions of the Hayward and Calaveras faults in the East and South Bay Area show this behavior. If the line of stations shows a sharp difference, then the fault is freely slipping or shows active creep. The San Andreas fault south of San Juan Bautista, the Hayward fault in the East Bay, and the Calaveras fault in the South Bay in Hollister shows this behavior. Unfortunately, all active faults don t behave the same.
Some faults creep, while other are stuck, while others have both types of behavior.
It's amazing that simply measuring the locations, distances, and angles between survey stations can tell us so much about how earthquakes happen. It's one of the tools that help us better understand our earth. Hopefully, as technology and knowledge improve, we may be able to predict earthquakes. In the past, we used visual or optical methods of surveying. The results were good enough to lay out property lines, but not good enough to use for high-quality earthquake studies.