运用细胞自动机模型模拟强震前地震活动时间演化过程  

Simulation of temporal evolution of seismicity before strong earthquakes using cellular automation model

作　　者：李纲[1] 刘杰[1] 傅征祥[1] 刘桂萍[2] 

机构地区：[1]中国地震局分析预报中心,北京100036 [2]中国地震局监测预报司,北京100036

出　　处：《地震》2004年第1期34-41,共8页Earthquake

基　　金：十五"国家科技攻关项目(2001BA601B02 02 04)

摘　　要：强震发生前震源及其周围地区可能会出现前震活动,这种前震活动可以分为二种:一种为连续型,即前震的频度或震级随时间渐渐增大,直至主震发生;另一种为不连续型,前震的频度和震级先增大后减小,然后发震。这种现象不但在破裂声发射试验中观测到,也在中国大陆地区多次强震前被观测到。文中基于细胞自动机模型,引入时间 状态依从摩擦本构关系,即把自组织非线性系统的普适特征与真实断层摩擦的具体特征结合起来,研究了强震前短期前兆地震活动的时间演化过程的机理。文中研究了模型中各参数对模拟事件时间过程的影响,结果表明,静摩擦强度在断层上的分布,或是说静摩擦系数的离散程度直接影响强震前地震活动时间演化过程。There may be foreshock activities occurred in hypocenter and the surrounding region before the strong earthquakes. There are two types of foreshock activities: first, the continuity one—the frequency and magnitude of foreshocks increase with time varying till the main shock; second, the discontinuity one—the frequency and magnitude of foreshocks increase earlier, then go down till the main shock. The phenomena are not only observed rupture test, but also before many strong earthquakes occurred in China, for example, the Haicheng earthquake with M_S=7.3 (March 4, 1975). In this paper, our research based on simulation using cellular automation model, in which we introduced the time-dependent friction mechanism, roughly indicates the friction characteristics of real faults. This model is close to the natural seismogenic system owing to the combination of the cellular automation model and the time-dependent friction mechanism. We use the model to research the temporal evolution of the foreshock activities. The model used in the paper is a simple model of seismogenic system on single fault. In our research, the model is varied with varying the parameters: the number of cells, the increment coefficient of stress loading, the increment coefficient of the internal static friction and the redistribution coefficient. Both two types of the foreshock activities can be found in long time rupture series obtained from the model. The results indicate that the distribution of static friction on the fault is important for the temporal evolution of seismicity before strong earthquakes.

关 键 词：震源 前震活动 细胞自动机 摩擦时间依从 单断层 

分 类 号：P315.33[天文地球—地震学]