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本文利用大地测量资料反演地震震源参数的一般理论,归纳为震源模型的建立、最优化计算的实施和观测资料的使用等三部分.文中着重研究了后两部分:提出了利用原始观测资料(地面长度、角度、高差、倾斜、应变的变化值)直接进行反演的严密方法;改进了单纯形最优化计算方法,加速了迭代的收敛并给出了收敛准则;按逐渐趋近法进行观测资料的标准化,保证了标准化后的各类资料都属于同一正态分布.文中根据地震前、后的大地测量资料,对1976年唐山7.8级地震的震源参数进行了反演,并对成果的稳定性和可靠性进行了检验,得到地震断层长度为112公里,走向为北东56°,倾角为90°,断层破裂至地面,断层面延深(宽)15公里,水平错距(右旋)2.51米,垂直错距(东南盘下降)0.70米,断层迹线中点位置为北纬39°36＇6、东经118°11＇4.由此计算得到的地震矩为1.45×10~(27)”达因·厘米,应力降为37.2巴,应变降为5.6×10~(-5).这个结果与根据地震波及震时其它地球物理资料求得的结果相近,因此认为本次地震前(或后),发生相当于主震规模的断层蠕动的可能性不大.
In this paper, the general theory of inversion of seismic source parameters using geodetic data is summarized, which includes three parts: the establishment of source model, the implementation of optimal calculation and the use of observation data. The last two parts are mainly studied: The length, the angle, the height difference, the inclination, the change value of the strain) directly; The simplex method of optimization calculation is improved, the convergence of iteration is accelerated, and the convergence criterion is given. The standardization of observational data ensures that all the normalized data belong to the same normal distribution.Based on the geodetic data before and after the earthquake, the inversion of the source parameters of the 1976 Tangshan earthquake of magnitude 7.8 is carried out, and the results of Stability and reliability. The result shows that the fault has a length of 112 km, a strike of 56 ° North East and a dip angle of 90 °. The fault ruptures to the ground with a depth of 15 km (horizontal) and a horizontal offset ) 2.51 meters, the vertical offset (southeast plate down) 0.70 meters, the mid-point of the fault trajectory is latitude 39 ° 36’6 north, longitude 118 ° 11’4. The calculated moment is 1.45 × 10 ~ (27 ) "Damien M, the stress drop is 37.2 bar and the strain is reduced to 5.6 × 10 -5 .This result is similar to that obtained from other geophysical data of seismic wave and epicenter, so it is considered that before (or after) this earthquake occurs The equivalent of mainshock-scale fault peristalsis is unlikely.