【摘要】 介绍了2008年3月21日新疆于田7.4级地震的基本参数、震区周围应力场背景及构造、地震序列特征等,分析了震前震区周围及相邻构造区域地震活动特征,对比分析于田序列和其后发生的汶川8.0级和乌恰6.9级地震的关系。结果显示,于田7.4级地震发生在阿尔金断裂与西昆仑断裂的交汇部位,可能是阿尔金断裂发生左旋扭错,牵引其西南端位于阿什库勒盆地的分支断裂发生张性破裂的结果。该地震序列为主-余型,最大余震为MS5.8,余震衰减较快,且具有一定的成丛性。震源机制解和震中分布可以看出,该地震具有单侧破裂特征。地震活动表明震前存在明显的中期和中短期异常,但未有短临异常出现。在汶川8.0级和乌恰6.9级地震前,该序列出现显著增强活动,具有一定的窗口效应。更多还原

【Abstract】 The parameters,stress field background and tectonics,seismic sequence et al.are introduced in the paper,analyzing the seismic activity characteristics in the epicenter region and its adjacent region before the earthquake and analyzing the relation between Yutian seismic sequence,Wenchuan M8.0 seismic sequence and Wuqia M6.9 seismic sequence contrastively.The result showed Yutian M7.4 earthquake occurred in the region between Arjin fault and Western Kunlun fault,it maybe caused by left-lateral dislocation of Arjin fault,it is the tensile fracture result of the fault in the west northern region of Ashiku basin;the type of the seismic sequence is main shock-after shock,the strongest aftershock is MS5.8 earthquake,the aftershocks attenuated quickly,and occurred in group;the focal mechanism and the seismic activity showed there was medium and medium-short term abnormity before the earthquake,but there was not short-imminent abnormity;the seismic sequence activity became active before Wenchuan M8.0 earthquake and Wuqia M6.9 earthquake,which was window effect in some extent.更多还原