摘要
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 modern tectonic stress field in Yunnan-Sichuan area by the statistic method of focal mechanisms parameters. The results show ed 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 dis- tributed in Yunnan. The earthquake occurred in Sichuan area had many types and scattering distribution.