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建立合于云南地区的速度结构模型,对云南数字地震台网记录的2000年姚安MS6.5地震3.0≤ML<5.0余震的垂直分量进行频率域内的地震矩张量反演。结果表明:矩张量分解得到纯膨胀(各向同性)分量P、纯剪切(双力偶)分量M0和补偿线性矢量偶极C三部分,其中纯剪切(双力偶)分量M0占主要部分,表明地震的震源破裂过程以剪切破裂为主。从余震震源机制解可知,NW—NWW方位的节面占主导,结合余震分布尺度可以判断发震断裂是北西向的断裂。
The velocity structure model in Yunnan is established. The seismic moment tensor inversion in the frequency domain is performed on the vertical component of 3.0≤ML <5.0 aftershocks of 2000 Yao’an MS6.5 earthquake recorded by Yunnan Digital Seismic Network. The results show that the component of pure expansion (isotropic) P, the pure shear (doubly couple) component M0 and the compensated linear vector dipole C are obtained by moment tensor decomposition. The pure shear (doubly couple) component M0 is the major part , Indicating that the earthquake rupture process mainly to shear fracture. According to the focal mechanism solution of aftershocks, the nodal plane of the NW-NWW is dominant. Based on the aftershock distribution scale, it can be concluded that the seismogenic fault is a north-west fault.