Research on present crustal deformation in the southern Tianshan (Jiashi) region by GPS geodesy

The pattern and range of present crustal movement as well as characteristic of deformation-strain play a key role in cognizing seismogenic mechanism in the Jiashi region, Xinjiang, northwestern China. Using GPS geodesy in 1994 and 1998, here we give geodetic evidence of rapid convergence of about 19 mm/a across the westem Tianshan, which is about 50% greater than the seismic moment solution (13 m/a) by assembling major enrthquake in the 20th century. The discrepancy of deformation rate between geodetic observation and seismic energy releasing indicates the possibilities that, there exists a lot of aseismic strain and strain during seismic interval in the westem Tianshan, or seismic fault slip in this century could not be enough to compensate the present deformation in the whole area. Whichever it maybe, from the view of accumulation of stress-strain, it suggests that there will be potential strong eathquakes in the western segment of Tianshan and the northeastern corner of Pamir in a long period.