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根据成层介质中面波的传播理论,考虑到介质的吸收、地球介质与763地震仪所组成的线性滤波器对面波振幅和周期的影响,并假定面波最大振幅对应于Airy相,则可从理论上导出测定面波震级的量规函数为: σ_(763)(△)=3.9+0.16(△/T_P)+1/3 Ig△+1/2 lg(sin△)+IgT_P (1°<△<179°)式中的T_p为Airy相对应的周期。该量规函数在震中距△=20°—160°范围内,与IASPEI所推荐的量规函数相一致,与实际观测资料在2°—178°范围內都拟合得很好。 σ_(763)(△)推广了IASPEI推荐的量规函数使用的震中距和周期范围,这点对我国特别重要,因为发生在中国而又被中国台网记到的地震,震中距大部分在1°—20°范围内。 用我国763长周期地震仪台网所观测到的垂直向面波最大振幅、周期资料,测定了103个地震的面波震级M_(S,763),其台网震级误差为0.14,比SK仪台网的(0.20)要小。与NEIS使用世界标准台网测定的真M_(SZ)相比较,发现M_(S,763)与M_(SZ)之间,在统计上无系统差,即△M_S=M_(S,763)—M_(SZ)的均值接近于零,而△M_S的标准误差为0.21级。
According to the theory of surface wave propagation in stratified medium, considering the influence of medium absorption, the influence of the linear filter composed of earth medium and 763 seismometer on the amplitude and period of the surface wave, and assuming that the maximum amplitude of surface wave corresponds to Airy phase, The gauge function for the determination of the magnitude of surface wave is derived theoretically as follows: σ 763 Δ = 3.9 + 0.16 Δ / T_P + 1/3 Ig Δ + 1/2 lg sin Δ + IgT_P 1 ° < △ <179 °) where T_p is the period corresponding to Airy. The gauge function within the epicenter distance △ = 20 ° -160 °, consistent with the gauge function recommended by IASPEI, fits well with the observed data in the range of 2 ° -178 °. The σ_ (763) (Δ) generalizes the epicentral distance and the range of cycles used by IASPEI’s recommended gauge functions, which is of particular importance to our country because the earthquakes that occurred in China but were recorded by the China National Grid were epicenters mostly at 1 ° -20 ° range. The surface wave magnitude M_ (S, 763) of 103 earthquakes was measured by using the maximum amplitude and period data of vertical surface waves observed by the 763 long-period seismograph network in our country. Network (0.20) to be small. Compared with the true M SZ measured by NEIS using the world standard network, it is found that there is no statistical difference between M S (763) and M SZ, ie, M S = M S (763) - The mean of M_ (SZ) is close to zero, while the standard error of ΔM_S is 0.21.