西-海-固地区垂直形变分析及地震趋势研究

Analysis of vertical crust deformation and study on the trend of earthquakes in Xiji Haiyuan Guyuan area

通过对西 (吉 ) -海 (原 ) -固 (原 )地区垂直形变场的演化分析表明 :1 90年代以来 ,垂直形变场升降差异运动减弱 ;2现今青藏亚板块对鄂尔多斯地块西南缘 (西 -海 -固地区 )的 NE方向挤压应力有所减弱 ,华北亚板块 SW方向挤压应力有所加强 ;3鄂尔多斯块体周缘小震出现的活跃状态 ,可能是由于青藏亚板块挤压应力的减弱而造成鄂尔多斯块体水平挤压应力场的“失稳”,以及华北亚板块挤压应力相对增强的结果。

By analyzing the evolution of vertical deformation field in Xiji Haiyuan Guyuan area, the following results are obtained: ① Since 1990, the differential movement of vertical deformation field has decreased. Today, activity of Liupan mountain fault zone is low. ② The compressional stress from Qinghai Tibet sub plate to the southwestern border of Ordos Massif along NE direction has become weak, but the compressional stress from North China sub plate along SW direction becomes stronger. ③ The reason why appears activity of small earthquakes, may be instability of horizontal stress field of Ordos block, due to adjustment of compressional stress form Qinghai Tibet plate and relative strengthening of compressional stress from North China sub plate.