This reminds me of a conversation I had with a colleague years back, who was working in geomapping, with some very sensitive GPS equipment. She shared a shocking fact with me, that any given point on the earth's crust, is flexing up and down on a daily basis, mostly due to tidal forces - (sun and moon gravitational forces, and also in response to ocean tides). Depending on what the ground is made of, local faults, etc, it can be as much as a few centimeters. Most geological survey data doesn't take this into account, except as a "margin of error" baked-in to permanent measurements.