Abstract: Using the GPS horizontal velocity field from 2009 to 2017 and the short-level cross-fault data from 1990 to 2018, the current three-dimensional crustal activity and main fault activity in Xichang are analyzed. The results show that the size and direction of GPS horizontal motion field and strain field change in Xichang area. The E-direction movement rate is reduced from an average of about 8 mm/a in the north to an average of about 4 mm/a in the south; the S-direction movement is bounded by the Anning-Zemuhe fault, and the movement rate of the west side point is obvios higher than that of the east side. The horizontal deformation field of the South China block also shows the difference in horizontal movements in Xichang. The main strain field is dominated by SW-NE tensile and NW-SE extrusion in Xichang area. The tensile and compressive strains on the east side of the secondary block of the Daliangshan are larger than the west side; the maximum shear strain rate is distributed in the form of strips in the secondary block, which is larger than the east and west sides; the horizontal horizontal motion velocity is compared with the deformation width. The results obtained from 1999 to 2007 are large, indicating that the Anninghe-Zemuhe fault zone is in the stage of shear strain accumulation, and the degree of occlusion is improved. Cross-fault level data shows that there is new signs of activity in the fracture and the stress continues to accumulate. Based on a comprehensive analysis of the results of the two data, it is speculated that the regional stress continues to accumulate and the seismic risk is further enhanced.

Key words: Xichang area, Horizontal movement, Strain accumulation, Fault activity, Seismic risk