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建立在用来解释地方震和区域地震的尾波散射模型的基础上,用云南短周期区域台网12个台站的 VGK 地震仪记录的68个禄劝地震的余震序列尾波观测资料,分六个时间段估算了尾波 Q 值.发现在所观测的频率范围内(0.40—1.65Hz),Q 值与频率有关,估算的 Q 值在80—240之间,频率相关值η=0.45.对表示散射强度的波源因子 B(f_p)的估算结果多数在10~(-23)—10~(-24)量级,低 Q 值地区表现出激发强度高.值得注意的是禄劝地震前后,离震中区较近的台站所测得的 Q 值发生了明显变化,有的变化达2.0倍以上.Q 值随时间的区域变化,这在地震预报中也许有重要的实际意义.此外,测定了余震震源参数.对震源参数间的定量关系的讨论结果给出:IgE=1.59M_L+11.335;E=(2.10×10~(-5)M_0;在3.0≤M_L<5.0的范围内,测定的震源破裂尺度 a=0.40—0.80km;应力降△σ=(6.0—130)×10~5Pa,一个显著的特征是应力降与地震震级不存在明显的线性关系.
Based on the coda wave scattering model used to explain the local earthquakes and regional earthquakes, 68 cadaveric earthquakes recorded by the VGK seismograph at 12 stations in Yunnan’s short-period regional network were used to analyze the coseismic observational data of aftershocks. The Q values of the coda were estimated over six time periods and found that the Q value was frequency dependent over the observed frequency range (0.40-1.65 Hz), with an estimated Q of 80-240 and a frequency-dependent value of η = 0.45. The results of the estimation of the wave source factor B (f_p), which indicates the scattering intensity, are mostly on the order of 10 -2 (-23) -10 ~ (-24), and the excitation intensity is high in the region of low Q. It is noteworthy that before and after the Luquan earthquake , The Q value measured by the station near the epicenter has changed obviously, some of the changes have reached more than 2.0 times, and the value of Q changes with time, which may have important practical significance in the earthquake prediction.In addition, The aftershock source parameters were determined.The discussion on the quantitative relationship between source parameters gave the following results: IgE = 1.59M_L + 11.335; E = 2.10 × 10 -5 M_0; in the range of 3.0≤M_L <5.0, The rupture scale of a source is a = 0.40-0.80km; the stress drop △ σ is (6.0-130) × 10 ~ 5Pa. A notable feature is the stress drop and earthquake magnitude Significant linear relationship.