Abstract: We calculated coseismic deformations at fiducial stations in China caused by the 2011 M9.0 Japan Earthquake. The results show that there are obvious coseismic displacements at stations located in the east, especially northeast of China, and the coseismic displacements are in directly proportional to the epicentral distance. The coseismic displacement at the SUIY station is the largest, 3.3 cm. A phenomenon is found in the time series that the speed of horizontal movements at the fiducial stations with obvious coseismic displacement decreased before the earthquake, and this phenomenon might be one of the earthquake precursors. Coseismic displacements and abnormal speed of movement before the earthquake collected by GPS data will be of profound significance for the study of predictive crustal movement, kinetic characteristics of earthquake and the crust velocity field in mainland China.

Key words: Coseismic displacement, CMONOC GPS, Japan M9.0 earthquake, Time series