震源构造发震概率的初步研究

A PRELIMINARY STUDY OF EARTHQUAKE OCCURRENCE PROBABILITY OF SOURCE STRUCTURE

“入”字型构造是一种发震构造几何类型。它亦即是一种重要的震源构造。本文用“入”型为造为例,以它的力学模拟计算数据为基础给出了一个计算震源构造发震概率的粗算方法。 本文取Poisson分布为震源构造处发震概率对有关物理量分布的原型。按我们的数据,一个具体构造的发震概率与震源处应变能密度最大值(e_max),最大破裂值(F_max)和泊松比倒数(1/v)的各自增减有关。为确定一个震源构造的发震概率,可先计算它在不同参数下的典型力学情况,然后以e_max,F_max和1/v作独立变量分别算出单位增量的发震概率。最后,再按公式P(e_max,F_max,v)=Ak(e_max-e°_max)(F_max-F°_amx)(1/v-1/v°)×exp{-(100η_1(e_max一e°_max)+100η_2(F_max-F°_max)+η_3(1/v-1/v°))} 计算该震源处的发震概率,其中e°_max,F_max和v°分别为它们的标准值,A与e_max,F_max和1/v单位增量发震概率有关,而放大系数k则与震源区断层本构律、其它有关物性和震源规模有关。 本文为从力学的数学实验计算数据提供了一个寻求震源处发震概率的初步方法。为此,本文已对本方法做过某些理论上的论证。从实际结果看,我们认为本方法有某种合理性,且结合实际可把它使用于其它几何构造类型。

“λ” type structure is a kind of geometric tectonic type of earthquake occurrence. It is also an important earthquake source structure, too. Taking such a structure as example, based on the mechanically simulated data the concrete approach to calculate earthquake occurrence probability of source structure is presented in this paper. The Poisson's distribution is taken as the prototype distribution of the probability to pertained physical quantity at source. In order to calculate an earthquake occurrence probability of a certain concrete structure, firstly the mechanical calculation is made under a typical status with different parameters and then the earthquake occurrence probability per unit increment is deduced when emax,, Fmax and 1/v are taken as independent variates. Lastly, the probability is figured out by the following formula. where e°max, Fmax and v° are the standard values, A is related to the probabilities of unit increments of emax, Fmax and 1/v, and k is the amplification coefficient. A preliminary method of getting earthquake occurrence probability of source structure from the mechanically caleulated data is presented in this paper. For this purpose, the method is confirmed theoretically. The obtained results show this approach a reasonable one. Combined with the practice, it may be applied to other geometric tectonic types.