Abstract: The 12 May, 2008 Wenchuan M8.0 earthquake has been the most devastating earthquake since the founding of the People's Republic of China. Its epicenter lies in the central part of the continuous GPS observation network and in the area with dense non-continuous GPS stations. There were plenty of GPS observation data before and after its occurrence and coseismic displacements of the earthquake were detected at many stations of continuous GPS observations. These coseismic displacements are the most evident crustal movements characterized with abrupt, simultaneous and significant changes, directly related to the earthquake occurrence. The displacement time series of continuous GPS stations outside the earthquake area show that coseismic horizontal displacements of this event appeared at stations in a large area, and were detected by many stations far away from the epicenter. They showed elastic rebound in comparison with the displacements before the event. The horizontal displacements before the earthquake and the coseismic horizontal displacements detected at continuous GPS stations revealed the connection between the horizontal displacements before the event in a large area and the process of the preparation of the earthquake. No significant coseismic horizontal displacements were detected in North China. No significant coseismic vertical displacements were detected outside the earthquake area. The coseismic displacements in the earthquake area are mainly permanent deformations with larger horizontal displacements and smaller vertical displacements. The characteristics and mechanism of coseismic displacements of the Wenchuan earthquake are studied in this paper. And furthermore the origin of the event, the main features of precursory crustal movements and their complicatedness are discussed.

Key words: Wenchuan earthquake, Crustal movement, GPS, Earthquake prediction, Time series, Coseismic displacement