海原断层系的分形研究

本文根据Okubo等人测量圣安德烈斯断层系所用的复盖维数法,对海原断层系进行了分形测量,求出海原断层系的整体维数D_0=1.137,其景泰段D_0=1.109,海原段D_0=1.182。计算中未得到邵家水段和李使堡段的分维数。此外,文中还着重探讨了断层几何与地震活动性及其力学环境的关系,进一步证明了自相似断层的几何复杂性与地震活动密切相关,剪切断裂带具较低分维数(1.1—1.3),而在张性环境中形成的断裂体系具较高的分维数(1.5—1.6)。最后本文讨论了断层迹线图等因素对分形测量精度的影响。

FRACTAL ANALYSIS APPLIED TO HAIYUAN ACTIVE FAULT SYSTEM

Based on the covering dimension method for measuring the San Andreas fault system applied by P.G.Okubo,the fractal behavior of Haiyuan Quaternary active fault system has been investigated.The fractal dimensions for the entire fault system and its two of the four segments,Jingtai and Haiyuan,are obtained,i.e.D_QB=1.137,D_OJ=1.109 and D_OH=1.182.The fractal dimensions for the other two segments,Shaojiashui and Lijunpu,aren''t obtained,so the SL segments are self-affine or nonlinear fractals rather than self-similar ones.It.may be seen that the real seismic faults are more complicated than ideal ones,should be multifractals or self-affine.Basides.the correlation between fault geometry and seismicity,mechanical circumstance around the fault system has been emphatically discussed.It further proves that the geometry complexity of self-similar faults is close to seismic activity;shear faults have lower fractal dimensions (1.1-1.3);but the fault systems formed in tensional circumstance have higher fractal dimensions (1.5-1.6).Finally,this paper discussed the effect of fault trace map,etc.on the measuring accuracy of fractal analysis.