GPS Data from Scripps Institution of Oceanography (SIO), IGS Global Data Center

The International GPS Service for Geodynamics (IGS) supports researchers who use satellites in the Global Positioning System (GPS) for studies in geodynamics. GPS satellites transmit signals that allow one to determine, with great accuracy, the locations of GPS receivers. The receivers can be fixed on the Earth, in moving vehicles, aircraft, or in low-Earth orbiting satellites. The time evolution of receiver locations allows researchers to study the motions of tectonic plates, displacements associated with earthquakes, earth orientation, and other geophysically interesting phenomena. Global Positioning System (GPS) uses microwave measurements of range (transmitter-to-receiver distance), accurate to within a centimeter or less, to determine positions of stations on the Earth's surface. Relative site positions can be measured to within a centimeter. This system was developed by the U.S. Department of Defense for military navigation and timing.

The International GPS Service for Geodynamics (IGS) ("http://igscb.jpl.nasa.gov/"), a service established by the International Association of Geodesy (IAG), officially started its activities on January 1, 1994, after a successful pilot phase of more than one year. The IGS provides GPS orbits, tracking data, and other high-quality GPS data and data products on line in near real time to meet the objectives of a wide range of scientific and engineering applications and studies.

Scripps Institution of Oceanography (SIO) is a Global Data Center within the IGS. It's mission is to archive high precision GPS data, particularly for the study of earthquake hazards, tectonic plate motion, crustal deformation, and meteorology. Data is available through the Scripps Orbit and Permanent Array Center (SOPAC): "http://sopac.ucsd.edu/"