The article doesn't mention it, but how are the coordinates of property boundaries recorded in South California to take into account the drift? In my relatively tectonically stable country there is a single coordinate system for the whole country. I'd imagine you need to record distance to a local landmark or similar? And what happens when there are shifts that end up in roads split in two like in Turkey last year? h…
Property boundaries aren't delimited by GPS coordinates, but rather a surveyor's instructions on how to locate the boundary from a set of known landmarks. In most US states, the Public Land Survey System [1] gives "meridians" and "baselines" for each region serving as the regional center. Radiating out, every 6 miles, is a new "township," with its corners serving as the local landmark for property boundaries.