Abstract: Strain accumulation in the triangles formed by observation stations is calculated from results of horizontal displacements obtained from GPS observations of several epochs during September 1998 to the end of September 2003, at the basic stations and fiducial stations in The Crustal Movement Observation Network of China (CMONOC). Because of the complicatedness of strain accumulation of small amount in time and space, strain accumulation in the basic network before and after the great Kunlun Mountain earthquake of M_S8.1 on Nov. 14, 2001 is analyzed on the basis of statistics. Before this event there was a process of intense crustal deformation in China's mainland, particularly in its western part, and in general, the directions of the maximum shear strain remained stable. These facts suggest that there was significant strain accumulation before this great event, in the area near the epicenter the rate of strain accumulation was rather low during 2000 to 2001 and there was lock of the faults or nucleation at the epicenter. The strike of the earthquake fault determined by the direction of maximum shear strain in a triangle which is the closest to the epicenter is N89.3°E. The deformation after the event was still large but the deformation in China's mainland, particularly in its eastern part the deformation became small during 2002 to 2003.

Key words: GPS, Fiducial station of the network, Basic station, Strain, Horizontal displacement