中国三个大地震的震源参数及讨论

SOURCE PARAMETERS OF THREE CHINESE LARGE EARTHQUAKES AND DISCUSSION

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M_0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。

By matching the teleseismic P waveforms with synthetic seismograms, the parameters of Tibet Yaojitaicuo earthquake of July 14, 1973 (Mr = 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 (?)1 = 177°, dip δ1- 51°, rake λ1 = - 99? (2) (?)2 = 11°,δ2 = 39°,λ2= -79°. The parameters of Yanyun earthquake of Nov. 6, 1976 (M, = 6.5) are: M0 = 2.2 × 1018N · m; r = 4.1s; H = 9km; the two nodle planes are (1) (?)1 = 42°, δ1 = 74°, λ1 = -160°; (2) (?)2 = 306°, δ2 = 71°, λ2= -17°. The parameters of Ninghe earthquake of Nov. 15, 1976, (Ms = 6.3) are: Mo = 1.5 × 1019N · m; τ = 8s;H = 17km; the two nodle planes are: (1) (?)1=59°,δ1 = 85°,llllllll1=170°;(2) (?)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.