Abstract: In this paper,the theoretical foundation of classification of focal mechanism solutions is drawn by the theory of shear dislocation,where the mechanisms of earthquake can be divided into the strike-slip fault,reverse fault and normal fault.The 124 focal mechanisms from Harvard University have been classified by the triangle diagram method in the area of Sichuan and Yunnan Provinces in China.The focal mechanisms of strike-slip,reverse and normal faulting have been discussed.These are the three deformation types in this area.The results show a SE-directed block movement of the Sichuan-Yunnan region.Along the Xianshuihe Fault,the Anninhe Fault,the Zemuhe Fault and the Xiaojiang Fault,large strike-slip movement and deformation have occurred.On the Sagaing Fault and the Longmenshan Fault,the reverse faulting mechanism dominates.The quick movement of the Red River Fault towards southeast driven by the Xiaojiang Fault forms a large tensional stress area between the Jinshajiang and the Xiaojinhe Fault.This constitutes the latest pattern of recent crustal deformation of Sichuan-Yunnan region and its adjacency.

Key words: focal mechanism solution, seismic classification, crustal deformation, crustal block, Sichuan-Yunnan region and its adjacency

摘要： 以位错理论为依据探讨了地震分类的理论基础,利用美国哈佛大学1977—2008年的震源机制解资料,采用地震三角形分类法,研究了中国川滇及邻近地区震源机制解124例,从地壳脆性变形的角度分析了川滇次级块体的变形形式。结果表明:整体上川滇及邻区的走滑断层、逆冲断层和正断层具有明显的分区性特征,受青藏高原SE方向的挤压,沿着鲜水河断裂带、安宁河断裂带、则木河断裂带和小江断裂带产生了大的剪切位移和变形带;同时,受缅甸弧挤压和四川盆地的阻挡,在缅甸弧前端和龙门山断裂带等地形成了强烈的挤压区,在云南大部分区域形成了扇形剪切应力变形区;而沿鲜水河断裂带、安宁河断裂带、则木河断裂带和小江断裂带所产生的大的剪切位移和变形直接作用在红河断裂带上,造成红河断裂带呈右旋向SE方向错动,引起其后延金沙江断裂至丽江-小金河断裂之间形成大的应力拉张区,构成了现今川滇及邻区地壳变形的最新格局。

关键词: 震源机制解, 地震分类, 地壳变形, 地壳块体, 川滇及邻近地区