Abstract: In this article,the fixed point deformation data of the west Chinese mainland had been analyzed by the analytical method of S transformation and overrun rate. The results show that abnormal signals with high frequency had been observed by some fixed-point deformation stations in the area of 600 km from the epicenter before the 2008 Wenchuan M_S8.0 earthquake and had lasted a longer time. The short-term and impending high-frequency anomalies are obvious in the area 300 km from the epicenter. In addition, the responses to high-frequency signals are not the same for different fixed-point derformation approach. Usually, high-frequency anomaly patterns of ground tilt are more sensitive and clear than crustal strain. Meanwhile, the results of S transformation and overrun rate analyses have good consistency, which indicates the reliablity of the extracted high-frequency anomaly.

Key words: Fixed-point deformation, High frequency abnormal signals, The 2008 Wenchuan M_S8.0 earthquake