Abstract:Based on comprehensive analysis of the research of deformation precursors at home and abroad, this paper, based on the results of GPS, strain and gravity before the Wenchuan earthquake, and applying the tilt data observed around the Wenchuan earthquake, puts forward the phenomenon of ‘fixed point’, that may occur in the focal area before the earthquake. The fixed point phenomenon in crustal deformation is an important marker of the critical state of regional stress field before earthquakes, and is an important basis for the delineation of seismic risk area. With the help of the fixed point theory, the evolution of the set of deformation fixed points before Wenchuan earthquake is shown, and the deformation fixed point phenomenon before earthquakes is also explained by thin plate theory. Finally, combined with the distribution of seismic activity and the far field significant deformation anomaly, we discuss the dynamic background of the deformation fixed point phenomenon, and verify that the fixed point phenomenon of the crustal deformation before the Wenchuan earthquake is the result of the orderly movement of the stress field in the large area.
NIU Anfu,ZHANG Lingkong,ZHANG Jing et al. On the Fixed Points in Crust Deformation prior to Wenchuan Earthquake and Dynamic Background[J]. jgg, 2020, 40(1): 1-6.