汶川地震前后太原盆地应力场变化特征研究

The variation characteristics of stress field of the Taiyuan Basin before and after the Wenchuan earthquake

利用小震震源机制解、地震视应力、GPS测量结果等资料,对汶川地震前后太原盆地应力场变化特征进行了研究。结果表明,汶川地震对太原盆地构造应力场的影响较为显著,不仅改变了应力场的方向,也改变了应力值的大小;应力场特征由震前NNE-SSW向拉张应力的局部小区域应力场为主,转为震后NEE-SWW向挤压应力为主且接近华北地区应力场。该变化态势有利于局部应变能积累,因而可能是太原盆地中小地震活跃的诱发因素。

The paper uses the results of focal mechanisms of small earthquakes,seismic apparent stresses,and GPS measuring results to study the variation characteristics of stress field in the Taiyuan Basin before and after the Wenchuan earthquake.The results show that the Wenchuan earthquake greatly affects the tectonic stress of Taiyuan Basin,not only in the direction of stress field but also in the stress value.The tectonic stress field of Taiyuan Basin is mainly the tension stress in NNE-SSW direction before the Wenchuan earthquake,and the compression stress in NEESWW direction after the Wenchuan earthquake which is close to the stress field of North China.The change is beneficial to the accumulation of local strain energy and it can be an inducing factor of the active moderate and small earthquake in the Taiyuan Basin.