Using data collected by the EarthScope Plate Boundary Observatory's GPS array, researchers identified 125-mile-wide "lobes" of uplift and subsidence. Over the last several years, the lobes, which straddle the fault line, have hosted a few millimeters of annual movement.

Computer models simulating the San Andreas Fault System have predicted such crustal movement, but the areas of motion hadn't been physically identified until now.

Researchers used advanced statistical modeling to identify the movement among the inevitable statistical noise that comes with monitoring minute movements in the Earth's crust.