Scientists at a conference in Washington released data from the 250 monitors on Thursday to various scientific centers nationwide, including the Jet Propulsion Laboratory in Pasadena.
The monitors also showed that seismic stress buildup, which increases the threat of earthquakes, is significantly less than had been believed in the San Bernardino area.
The global positioning system monitors track movements of the Earth's crust against satellite orbits. They allow scientists to measure shifts as tiny as one millimeter a year, and have allowed researchers since the 1994 Northridge quake to more accurately determine where stress is building along Southern California fault lines.
"GPS is a critical tool to understand the earthquake problem in Southern California," said U.S. Geological Survey seismologist Lucy Jones. "We cannot do it simply from the surface."