The extraction of the near-field deformation features along the faulted zone based on PS-InSAR survey

The near-field deformation is not only important for earthquake forecast and Neotectonics study but also important for the service to engineering geology. Adopting PS-InSAR（Persistent Scatterer Interferometric Synthetic Aperture Radar）technology and using L band data, the authors conducted the survey of near-field deformation around Bamei-Daofu section of Xianshuihe active fault from 2007 to 2011 and, based on analysis in combination with other materials, inferred some complex fault near-field deformation information: ①the deformation velocity of the north section is larger than that of the north section, and velocities on the two sides of the fault are somewhat different from each other, the velocity of SW wall is large than that of NE wall, the velocity difference of the far-field is more significant, and the velocity of the near-field is feeble; ②in area close to the active faulted zone, the values of PS（Persistent Scatterer）points deformation velocities are mainly comparatively small negative and positive values, reflecting the surface ascent and suggesting that the location is composed mainly of wet land, exposed point of ground water, bank and gully. It is inferred that these phenomena are attributed to surface bulging and deformation caused by weather warming—glaciers melting—uplift of ground water level, the tendency uplift of wet land resulting from seasonal frost heaving, and certain expansibility of cataclastic rock and soil near the faulted zone; ③the uplift deformation around Zhonggu-Bamei section results from the thrust movement near Xianshuihe fault, and the ductile shear zone absorbs and coordinates the entire block deformation; ④high deformation PS blocks reflect the slope gravity deformation，especially in sections of Daofu-shonglinkou and Qianning basin-Longdengba, revealing the geohazard effects of the fault; ⑤the precise PS-InSAR results show that the deformation of the fault is complex and shows remarkable differences in different sections, different periods and different tectonic locations, so we can't simply consider the movement to be overall translation or elevation-subsidence with the faulted zone as the boundary.