Application of GPS in Combination with Repeated Gravimetry for Monitoring Time-Dependent Process

Repeated GPS and gravity measurements carried out for geodynamic purposes along a profile from Antofagasta across the Cordilleras in western direction up to Gran Chaco within a period of almost a decade are discussed. The underlying principles from Datum problems up to the use of gravimetry for determining dynamically useful height variations are considered in detail. Presently, still the vertical component of GPS-measurements has lower accuracy than horizontal dislocation components. This is the main reason why rather long periods of observation (longer than a decade) are necessary to obtain meaningful accuracy. With modern IGS, GIG or similar orbits for GPS, however, improved data are ahead. This implies a substantial change in using GPS techniques for geodynamic purposes also over longer distances. Future plans in view of this new development are explained.