Simultaneous estimation of secular and episodic crustal motion via geodetic observations

Repeated high quality geodetic observations allow the estimation of the free surface velocity field for a region. Usually, a yearly secular rate is estimated, while the possible episodic motion (seismic slip) due to an earthquake is evaluated via inversion of the geodetic data. The episodic motion influence is subtracted from the total field. The actual region and the respective geodetic observations affected by the seismic event are often assessed by rather vague criteria.This paper deals with an attempt to estimate simultaneously the secular and the episodic two-dimensional crustal motion for a region by means of repeated GPS observations of a geodetic network, carried out for a number of epochs.The model is applied to the Gulf of Corinth available GPS data, spanning a time interval of more than a decade, and the results are discussed.