山西地区应力场变化与地震的关系

收集了1970～2006年37年的小震初动符号建立了震源机制解数据库,研究了山西断陷带小震综合机制解时空演化特征.结果表明:山西断陷带小震综合机制解以走滑正断层为主,断陷带两端以拉张作用为主,中部地区以剪切作用为主,忻定盆地、太原盆地的区域应力场与华北区域应力场差异较大.利用沿山西断裂带布设的GPS监测网1996～2007年12期复测资料,分析了山西断裂带水平运动与地震活动的关系.结果表明:山西断裂带现主要受NWW-SEE向压应力场、NNE-SSW向张应力场的控制.1998～1999年有一次较为明显的应力扰动,空间上表现为北强南弱,接着发生了1999年11月1日大同-阳高5.6级地震.

Research on relationship between stress field variation and earthquakes in Shanxi area,China

Based on the focal mechanism solution database established by collecting 37 years initial motion of small earthquakes (1970~2006), the space-time evolution characteristics of small-earthquake integrated mechanisms in Shanxi fault zone are studied in this paper. The results indicate that small-earthquake integrated mechanisms in Shanxi fault zone are mainly dominated by strike slip normal faults, at the two ends dominated by extension tectonics and in the central region by shearing. The difference between the stress field of Huabei and the regional stress fields of Xinding and Taiyuan Basins is very large. The relationship between horizontal motions and earthquake activities in Shanxi fault zone is analyzed according to the 12 stages of re-measuring data of GPS monitoring network along the Shanxi fault zone (1996~2007). The results indicate that the Shanxi fault zone now is mainly controlled by compressional stress along NWW-SEE direction and tensile stress along NNE-SSW. One obvious stress disturbance occurred during the period of 1998~1999, which was stronger in the south than in the north. This was followed by Datong-Yanggao M5.6 earthquake on 1st Nov.1999.