通过消除S波观测谱中的传播路径、场地响应、仪器响应等影响因素,得到中小地震的震源谱。根据Brune震源模型,运用遗传算法计算了地震矩、应力降、震源半径等震源参数; 通过考虑由于有限的仪器带宽带来的地震辐射能量低估及补偿问题,测定了中小地震辐射能量; 分析了云南地区ML2.0～5.3地震静力学和动力学参数定标关系。结果表明:地震矩为2.1×1012～1.2×1016N·m,地震矩M0和震级ML的线性关系式为lgM0=1.01ML+10.59; 震源破裂半径在86.9～1220.4m之间,地震矩M0与震源半径a之间的关系式为lgM0=0.003a+12.90; 应力降结果介于0.03～57.55MPa之间,当M0<4×1014N·m时,应力降随地震矩的增大而增大,当M0≥4×1014N·m时,应力降与地震矩之间无明显的依赖关系; 地震矩M0与拐角频率fc明显有依赖关系,二者之间的关系式为lgfc=-lgM0+5.32; 地震辐射能量ER在3.01×106～2.06×1012J之间,地震辐射能量ER与震级ML之间的关系为lgER=1.18ML+5.69。当M0<4×1014N·m时,折合能量有随地震矩增大而增大的趋势,当M0≥4×1014N·m时,折合能量不随地震矩的增大而变化; 地震视应力范围为0.02～31.4MPa之间,视应力与震源深度之间没有明显的依赖性。

The observational seismic S waveform data are corrected by removing the propagation, site effects, instrument etc, and source spectra for the moderate and small earthquakes are obtained. Based on Brune source model and by means of generalized inversion technique, we determined the source parameters including seismic moment, stress drop, source dimension etc. And we estimated the radiated seismic energy for moderate and small earthquakes with the possible underestimation by limited bandwidth recording taken into account. We analyzed the scaling relations of static and dynamic parameters for earthquakes with ML2.0 ~ 5.3 in the Yunnan region. The results show that the seismic moment is between 2.1 xl0 12 N·m and 1.2 x l0'6N-m, and there is a linear relation of lgMo = 1.O1ML + 10.59 between the seismic moment and local magnitude. The source dimension varies from 86.9m to 1220.4m. The seismic moment and rupture radius remain a linear correlation oflgMo = 0.003a + 12.90 . The stress drop is in the range of 0.03~57.55MPa, and the stress drop increases with seismic moment for Mo ＜4 x l0 14N·m, while it doesn't vary with seismic moment for Mo ≥4 x l0 14 N·m. The seismic moment shows dependence of the corner frequency. Assuming the constant stress drops, we can obtain the relation oflgfc= - 1/3lgMo + 5.32 between the seismic moment and corner frequency using least squares fitting. The theoretical radiated seismic energy is between 3.01 x l0 6J and 2.06 x 10 12J. The linear relation between the radiated seismic energy and local magnitude is lgER = 1.18ML + 5.69. The scaled energy increases with seismic moment for Mo ＜4 x l0 14N·m. However it seems that the scaled energy doesn't vary with seismic moment for Mo≥4 x l0 14N·m. The apparent stress is in the range of 0.02 ~ 31.4MPa. The apparent stress also seems independent of the seismic depth.

云南省应用基础研究重点项目(2010CC006); 云南省重点项目(JCYB-20080601-4); 地震科学联合基金(C08065)联合资助