【摘要】 本文针对2008年汶川地震后鄂尔多斯块体周缘出现的小震活跃现象,利用分布于汾渭断陷带不同部位的跨断裂水准资料,分析了其近期的垂直形变演化过程。结果表明:①各水准剖面的垂直差异运动幅度基本稳定在±20mm之间,且在小震活动期间未出现明显的形变异常;②鄂尔多斯块体周缘近期小震活跃可能是缘于汶川地震后,青藏块体挤压应力减弱,华北块体对其推挤作用相对增强而造成鄂尔多斯块体的水平挤压应力场的"暂态失稳"所致。更多还原

【Abstract】 In order to investigate seismicity in the peripheral areas of the Ordos block after the 2008 Wenchuan earthquake,we analyzed evolutive course of the current vertical deformation in the Fenwei fault-depression zone using fault-crossing leveling data situated on different locations.The following are obtained: ① the vertical movement extent of ascending and sinking difference is about 20 mm,and there is no obvious exceptional deformation;② Small earthquake activities may be transient instability of horizontal stress field of Ordos block,due to adjustment of compressional stress from Qinghai-Tibet plate and relative strengthening of compressional stress from North China sub-plate.更多还原