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根据简化的地震波传播理论,“漫化”地震能量在空间的分配,减弱能量空间分布概率的极端情形及消除统计子域为“空”的情形,由此构造类似于二维fBm的地震能量空间分布概率曲面。与起伏不平的地形相似,由于其在水平方向及垂直方向的变化不是等比例的,因而这一分形曲面可能是统计自仿射的。 选择中国大陆部分7级以上地震及华北地区部分6级左右地震为震例,利用傅里叶变换方法对中、强地震前后能量空间分布概率曲面的分形特性及其变化进行研究,目的在于由此探寻可能的震兆信息。结果表明,尽管分形结构及其时间演变复杂,但在某种意义上仍有一定的规律可循。从分形维数的变化来看,除降维外大震之前出现的多度域现象是大震的一个显著前兆现象,也是与6级左右中强地震的显著区别之一。指出地震能量空间分布的多度域分形现象不但可能与区域介质性质有关,而且可能与区域应力状况及区域介质所储存的能量大小有关。
According to the simplified theory of seismic wave propagation, the distribution of “diffuse” seismic energy in space, weakening the extreme case of the probability of spatial distribution of energy and eliminating the statistical sub-field as “empty”, the seismic energy space similar to 2-D fBm is constructed Distribution probability surface. Similar to an undulating terrain, this fractal surface may be statistically self-affine because of its non-proportional scaling in the horizontal and vertical directions. This paper chooses some earthquakes of magnitude 7 in the Chinese mainland and some of the 6 earthquakes in North China as examples, and uses the Fourier transform method to study the fractal characteristics and changes of the energy spatial distribution probabilistic surface before and after moderate and strong earthquakes. Explore possible earthquake information. The results show that although the fractal structure and its time evolution are complex, there are still certain rules in some sense. From the perspective of fractal dimension change, the appearance of multi-degree fields before large-scale de-dimensioning is a significant precursor of large earthquakes and is also one of the significant differences from moderate-level 6 earthquakes. It is pointed out that the multi-degree fractal phenomenon of spatial distribution of seismic energy may not only be related to the nature of regional media but also related to regional stress conditions and the amount of energy stored in regional media.