分形方法在地震序列类型早期判别中的应用

着重讨论了地震序列的空间分布随时间变化的特性，利用分形方法提取大震后余震的空间分维信息，从而达到早期判别地震序列类型的目的。以１９６６年以来定位精度较好、余震记录较全的１２个７级以上大震和大同６级强震序列为资料，计算了震后１个月内余震随时间变化的空间分维数。结果发现，不同类型的地震序列分维数不同。一般震后５－６天，主震型序列的分维数在１．１－１．２之间，多震型序列的分维数在１．３以上。利用前７天的

APPLICATION OF FRACTAL TO THE EARLY JUDGEMENT OF SEISMIC SEQUENCES

In this paper, the characteristics of the spatial distribution of the seismic sequences that varied with time are discussed. By using the fractal technique, authors obtained the fractal information of the aftershocks after mainshock occurrence, and reached the purpose for judging the types of seismic sequences. On the basis of the data which involve 12 large earthquakes and one moderate earthquake, authors calculate the fractal dimensions of these earthquakes, and find that the values of the fractal dimensions are different for different earthquakes. Generally speaking, the value for the mainshock -aftershock type 5 - 7 days after the mainshock is between 1.1 to 1.2. and the value for the swarm type is greater than 1.3. The accuracy of judging the type of seismic sequences can reach 84.6%. It is possible to judge the type of a seismic sequence earlier by using this technique.