中国三个大地震的震源参数及讨论

大地震的震源机制及地震矩、应力降等参数,不(又对认识地震的破裂过程,而且对预报强地面运动都是非常重要的。一些文章对板内地震应力降的特点、地震矩与高频源谱的关系及区域特征的讨论,使我们可直接由长周期体波或面波得出的地震矩M₀估计出不同地区中大地震的高频源谱,以供强地面运动预报参考。 由于对发生在中国板内的1976年11月6日盐源地震（M_s=6.5）和1976年11月15日宁河地震（M_s=6.3）的震源参数还没有详尽的报道;另外,对1973年7月14日

SOURCE PARAMETERS OF THREE CHINESE LARGE EARTHQUAKES AND DISCUSSION

By matching the teleseismic P waveforms with synthetic seismograms, the parameters of Tibet Yaojitaicuo earthquake of July 14, 1973 （M_r = 6.9） are obtained: seismic moment M0 = 3.6×10¹⁸N · m; duration of source rupture r = 8s; depth H= 17km, the two nodle planes are:（1） strike （φ）₁ = 177°, dip δ1- 51°, rake λ₁ = - 99°（2）（φ）₂ = 11°,δ₂ = 39°,λ₂= -79°. The parameters of Yanyun earthquake of Nov. 6, 1976 （M_s = 6.5） are: M₀ = 2.2 × 10¹⁸N · m; r = 4.1s; H = 9km; the two nodle planes are （1）（φ）₁ = 42°, δ₁ = 74°, λ₁ = -160°; （2）（φ）2 = 306°, δ2 = 71°, λ₂= -17°. The parameters of Ninghe earthquake of Nov. 15, 1976, （M_s = 6.3） are: M_o = 1.5 × 1019N · m; τ = 8s;H = 17km; the two nodle planes are: （1） （φ）1=59°,δ₁ = 85°,λ₁=170°;（2）（φ）2 = 329°,δ2 = 80° λ₂ = -5°.We compiled the seismic moments of other 18 Chinese intraplate earthquakes （Ms≥5.8） and 39 subduction shallow events （6.7≤Md≤8.2）. Comparing the two sets of data, the following results "are obtained: on the average, Mo values of Chinese intraplate events are smaller than those of subduction-zone events with the sane M, values; the apparent stress are from 5×10⁵ to 30 × 10⁵ Pa and 50×10⁵ to 90×10⁵ Pa for most subduction-zone events and Chinese events respectively.