This includes not merely the interseismic compression but also a possible "slow" earthquake that may occur in different depth along the seimogenic zone. Moreover, the redistribution of strain connected with the spatio-temporal clustering of earthquakes can also be observed. Aim of this component is to provide a continuous stream of GPS time series for joint interpretation with conventional seismic data. Traditional seismic data obtain the surface displacement by a double integration of acceleration measurements (strong motion instruments) or by deconvolution of the instrument response and integration of the velocity measurements (broadband instruments). The accuracy of absolute displacements derived with seismic instruments is poor due to the bandwidth and the dynamic range limits of seismometers. In contrast geodetic methods (GPS instruments) do not have this problem: here the ground displacement is measured directly. Unlike the seismometer, the GPS receiver never saturates, however, seismic measurement provides a powerful constraint on the much noisier GPS measurements.  The combination of high-rate GPS displacements and traditional seismic data will extend the frequency range of surface displacement data that classically produced daily coordinate time series. Contrasting to seismic data, geodetic data requires extensive processing before geophysical interpretations can be made. Therefore an automated processing and monitoring system is developed which continously produces time series and velocities. The data could be viewed and shared via a web interface.

For further details see the IPOC homepage and the GNSS webinterface.

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