Abstract：The characteristics of crustal deformation in the area around Longmenshan fault zone before Lushan M7.0 earthquake and Wenchuan Ms8.0 earthquake were analyzed with the data from GPS stations located in the Longmenshan fault zone.The initial result indicates that：(1）Both of the two seimic events occured the fault segment with low strain rate where was compressed and shortened;（2）Due to adjustment of crustal deformation after Wenchuan Ms8.0 earthquake，the horizontal strain rate in the southern segment of Longmenshan fault zone increased obviously.However，the location where Lushan M7.0 earthquake occured still was a low value area with a strain rate of 30 nanostrain/a，while the strain rate in the surrounding area was more than 60 nanostrain/a.The reason formed this phenomenon could be the area where large earthquake will occur was in critical state of breaking，and the accumulation of plastic deformation reaches limit state.Therefor，the increment of crustal deformation or strain rare in the area would keep low value.
Zhou Demin,Gan Weijun,Li Jinping et al. STUDY ON CRUSTAL DEFORMATION FIELD BEFORE THE “4.20”Ms7
EARTHQUAKE IN LUSHAN，SICHUAN[J]. jgg, 2014, 34(5): 1-5.
