摘要
本文由区域台网地震波资料，反演得到１９７６年云南龙陵地震群６０２个中小地震的震源机制解。文中对机制解的各参数进行了分析和系统聚类。结果表明：小震机制解的优势取向和主要类型与序列中的大地震震源机制一致。反演得到震源区应力场方向为：最大压应力主轴方位１９５°、仰角５°；中等压应力主轴方位３１４°、仰角７９°；最小压应力主轴方位１０４°、仰角１０°。这与其它资料给出的结果相符。虽然区域应力场的平均方向比较稳定，但震区仍受到震源区应力场调整作用的影响，因而龙陵震群的走滑型的小震机制表现出一定程度的离散性，并且正倾滑动和逆倾滑动类型的小震机制独立存在。小震机制解节面走向相对均匀地散布在各个角域，成为该序列小震机制的一大特点，分析认为这和震源处＂准均质＂的介质条件有关。
Focal mechanisms of 602 small and moderate events of Longling earthquake swain occurred in Yunnan in 1976 have been derived from seismic waves recorded at the local network. The mechanism parameters have been discussed by hierarchical clustering analysis in this paper. The results indicate that orientations and dominant types of source mechanisms to small events are identical with that to strong earthquakes. The results obtained by inversion are that azimuth and elevation of maximum compressional axis for strees field are 195°and 5°, 314° and 79° for middle compressional axis, and 104°and 10° for minimum compressional axis, which are identical with the data from other sources. Although average orientations of the regional stress field are relatively stable, the scarcearea is affected by stress field adjuctment. Therefore strike slip mechanism of small events of Longling earthquake swarm shows scatter features to some extent, furthermore, mechanisms of normal and inverse dip slip for small events exist independently. The strikes of nodal planes of mechanisms to small events are well - distributed which is a significant features to the sequence, probably related to quasi - homogeneous media in source area.
出处
《地震研究》
CSCD
北大核心
1996年第4期331-339,共9页
Journal of Seismological Research
基金
地震科学联合基金
关键词
地震群
震源机制
应力场
云南
地震
seismic awarm
focal mechanism
stress field
Yunnan
