【摘要】 首先对具有代表性的重力异常分离方法进行简单介绍,在此基础上使用这些方法对同一组理论模型数据进行试验,优选出异常分离效果较好的优化滤波法对芦山地震震区重力异常特征进行分析,初步认识此次地震发生的深部构造背景,得出以下初步结论:龙门山断裂带在研究区布格重力异常中反映为一条近北东走向的显著重力梯度带.该梯度带在天全附近分为两支,芦山地震震区靠近重力梯度带分叉处,且MS≥3.0余震同样呈近北东向展布,与梯度带走向基本一致,认为此次强地震的发生与重力梯度带下的深部结构及构造活动密切相关;芦山地震震区浅部结构与深部构造特征存在较大差异,构造复杂及地壳深浅部耦合关系较差,说明此次强地震的发生受浅部和深部构造的共同控制.更多还原

【Abstract】 This paper firstly introduces the gravity anomaly separation methods,then adopts the preferential filtering method to analyze the characteristic of gravity field in the Lushan earthquake zone and its adjacent areas,so as to shed some lights on the tectonic background of the earthquake in the subsurface.The preliminary understandings are:① A remarkable gravity gradient zone(GGZ)trending NE presents along the Longmenshan faults zone,and to the south of Tianquan county it is splitted into two branches;② The epicenter of this earthquake is near the crotch of the GGZ,and the aftershocks with MS≥3.0 strike NE,which is consistent with the strike of the GGZ.All the results indicate thatthe generation of this earthquake is closely related to the deep structure and tectonic activities beneath the GGZ.There is a large difference between shallow structures and deep ones in Lushan earthquake zone,in addition,complex structures as well as poor coupling between shallow and deep part of the crust also exist,implying the generation of Lushan earthquake was controlled by both shallow and deep structures.更多还原