STUDY ON STRAIN FIELD AROUND ZHANGJIAKOU-BOHAI SEISMIC BELT WITH LEAST-SQUARE COLLOCATION
利用最小二乘配置方法研究张家口-渤海地震带周边地区应变场

We collected and combined all mobile GPS data between 1999 and 2009 around Zhangjiakou-Bohai seismic belt,and obtained the velocities at 143 stations.At the same time,we constructed a regional strain field of the Zhangjiakou-Bohai seismic belt region with least-square collocation,and investigated the slip rate of Zhangjiakou-Bohai belt.The study results show that: 1) the regional maximum displacement is about 5 mm/a,2) Zhangjiakou-Bohai seismic belt is creeping in with left-lateral slip rate of 2.0 mm/a and the creeping depth is in a range of 25-45 km,3) The maximum shear strain is 3×10-8/a in Beijing-Tianjin and Tangshan area.