Using GPS and Other Crust Deformation Data for Research the Some Common Characteristics of Tectonic Deformation Abnormity Before the Strong Earthquake

Abstract eng:
By the high-precision GPS and repetition leveling data observed from the northeast margin of the northeast margin of Qinghai-Tibet plateau and by comparing them with geological structures and strong earthquakes activities in this area, the some common characteristics of regional tectonic deformation abnormity before the strong earthquake are studied. The results show that: a).For horizontal movement-deformation , it shows features of centralized high strain area (or zone) of dominating shear deformation related to active block and faults; b).For regional vertical deformation, it shows distribution features of abnormal apophysis area and dense belt-high gradient belt of vertical difference deformation (some of them reflect distribution of four quadrants) related to tectonics; c).Common features of regional vertical deformation abnormity area and high strain distribution area of horizontal deformation. Having analyzed preliminarily formation mechanism of these common characteristics of abnormity, it concludes that: these are results, controlled by basic united tectonic stress field of large-range, caused by stress-strain accumulation and certain phase strong earthquake, according to deformation difference brought about on tectonic position in the boundary zone and inner second-order faults of active blocks by unstable and inharmonious features for movement of block system of different levels and deformation of boundary. Based on above, the meaning of medium-term prediction of strong earthquakes is discussed, grounding on common features of regional deformation abnormity, and combining with background of geological tectonic activities.

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