地震断裂系统的分形和在地震预报中的应用

FRACTAL OF SEISMIC FRACTURE SYSTEM AND ITS APPLYING IN EARTHQUAKE PREDICTION

本文基于地震断层具有自相似结构,从分形概念出发,依据地震资料提出了适合于前震和余震的分形模型,在此基础上讨论了前震和余震的b值特征,提出了地震矩不均衡度的概念。本文还探讨了利用分数维和地震矩不均衡度进行地震预报的可能性。研究发现,正常情况下,地震矩不均衡度呈现低值,大震发生前出现高值异常,震后降低;在空间上,震前2—4年其异常范围大,震前一年异常区逐渐缩小,大震发生在异常集中区内或其边缘。

The fault systems of earthquake are non regular whether in laboratory test scale or in, geologic scale, which have self similar structure. After a earthquake, the slip function of seismic fault reached the largest value in the middle segment of fault and reduced to the smallest value in two ends of it. The remainder strain caused by the mainshock was gradually adjusted by the faults of aftershock, which have different scales and different directions. The seismic fracture system formed by the mainshock and aftershocks has shown the fractal character. Two structure models of foreshock and aftershock system have reported in this paper. Based on this result the non-balanced degree of seismic moment in a seismic fracture system has beendefined. It is found that before some strong earthquakes the fractal dimension and the non-balanced degree of seismic moment show temporal and, spatial changes. The applying of fractal di mension and non-balanced degree of seismic moment in earthquake prediction are discussed.