由震源机制解资料研究川滇地区构造应力场

Research on Structural Stress Field Basing on Focal Mechanism Solutions Data in Sichuan-Yunan Area

利用1978～2009年川滇地区的124个地震震源机制解资料,采用对震源机制参数统计的方法,详细分析了地震断层类型和川滇地区的现代构造应力场特征。结果表明,云南地区(21°～28°N,97°～108.8°E)主要受近N-S向的水平挤压力影响,区域应力场背景以水平作用力为主;四川地区(28°～34.5°N,97°～108.8°E)由于平均P,T轴的仰角接近水平,构造应力场接近水平,主要受近E-W向挤压力作用,断层面较陡,受水平剪切力作用。川滇地区走滑型地震较多,主要分布于云南地区,四川地区内发生的地震类型较为分散且每种类型都有。

Basing on 124 focal mechanisms data from 1978 to 2009 in Sichuan-Yunan area, we analyzed the fault type of earthquake and the characteristic of modem tectonic stress field in Yunnan-Sichuan area by the statistic method of focal mechanisms parameters. The results showed that it was influenced by horizontal compression in nearly NS direction in Yunnan area （21° -28°N, 97° -108.8°E）, and the main characteristic of regional stress field background is characterized by horizontal compression. Because of the average plunges of P-axis and T-axis were close to horizontal, the tectonic stress field which is close to horizontal mainly influenced by compression in nearly EW direction in Sichuan area （28° -34. 5°N, 97° -108.8°E） . The fault plane which was influenced by horizontal shear tress is stepper. The main type of fault is strike-slipe in Sichuan-Yunnan area, and mainly distributed in Yunnan. The earthquake occurred in Sichuan area had many types and scattering distribution.