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本文根据 K.Aki 提出的地方震尾波散射理论,建立了适用于云南地区测定近震震级的尾波震级标度 M_c 的理论公式:M_c=4.88+(1/1.10)lgU(f_p)~(-1)+0.78lg(△/α+t_(Du))+0.04(△/α+t_(Du))~(7/12)用云南短周期区域台网的11个 VGK 地震仪器纪录的110个近震尾波观测资料,计算了尾波震级 M_c,为了比较,同时也计算了持续时间震级 M_D。结果表明,在 M_L<5.0级的范围内,M_c 与 M_L 无系统差,平均标准误差比 M_L 和 M_D 小,由通常的0.20～0.26下降到0.10～0.15左右。最后给出三种震级标度的水平向换算关系为:M_L=1.11M_c-0.377;M_L=1.10M_D-0.379;M_D=1.009M_c+0.002。根据尾波散射理论建立的尾波震级标度 M_c 由于它不仅与振幅 A(t)震中距△有关,而且与震源参数、介质特征和仪器系统响应也作为相对独立变量考虑,因而有更明确的理论和物理基础。
In this paper, according to K.Aki’s theory of local seismic wave scattering, a theoretical formula for the magnitude of the wake magnitude M_c applied to the near earthquakes in Yunnan Province is established: M_c = 4.88 + (1 / 1.10) lgU (f_p) ~ -1) +0.78lg (Δ / α + t_ (Du)) +0.04 (Δ / α + t_ (Du)) ~ (7/12) The results of 11 VGK seismic instruments recorded by Yunnan short- Near-end coseismic observational data were used to calculate the wake magnitude M_c. For comparison, the duration magnitude M_D was also calculated. The results show that there is no systematic difference between M_c and M_L in the range of M_L <5.0, and the average standard error is smaller than that of M_L and M_D, from 0.20 to 0.26 to 0.10 to 0.15. Finally, the horizontal scaling relations of three magnitude scales are given as: M_L = 1.11M_c-0.377; M_L = 1.10M_D-0.379; M_D = 1.009M_c + 0.002. The coda scale M_c established by coda wave scattering theory is not only related to the epicentral distance △ of amplitude A (t), but also considered as relative independent variables with respect to source parameters, medium characteristics and instrumental system responses. Theoretical and physical basis.