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本文引入空间距离方法用于定量分析地震空间分布特征,所定义的地震空间分布因子Z_K可以较好地判断地震空间分布类型,当Z_K→1时表征地震空间分布具有丛集的特征,Z_K在0.5附近波动说明空间中地震是随机分布的;Z_K→0则可能对应于地震的网格分布图象。从更深层次上来看,ZK值的变化从地震空间分布的角度出发,在某种程度上反映了孕震系统有序复杂程度的动态变化。 以1970年以来华北地区10次M_s≥5.8地震为例,对Z_K值在中强地震前后的变化特征进行了探讨。结果表明中强地震前普遍地可检测到高Z_K异常值,具有实用意义的是可以统一地取Z_(αυ=0.642作为异常判断标准。两个7级以上强震前的高Z_K异常值一般持续时间较短、上升较快、幅度较大,强震发生于Z_K最大值附近。中强地震前的高Z_K异常则持续时间较长、变化平缓、异常幅度较小,地震多于异常结束后一年多的时间内发生。 最后本文就震级下限、区域范围对Z_K值的影响等其它一些问题进行了讨论。
In this paper, the spatial distance method is introduced to quantitatively analyze the spatial distribution of the earthquake. The defined spatial distribution factor Z_K can be used to determine the type of the spatial distribution of the earthquake. When Z_K → 1, the distribution of the spatial distribution of the earthquake is clustered. Z_K is around 0.5 Fluctuations indicate that the earthquakes are randomly distributed in space; Z_K → 0 may correspond to the grid image of the earthquakes. From a deeper perspective, the change of ZK value reflects the dynamic change of the order complexity of the seismogenic system to a certain degree from the perspective of the spatial distribution of the earthquake. Taking 10 M_s≥5.8 earthquakes in North China since 1970 as an example, the changing characteristics of Z_K values before and after the moderate-strong earthquakes are discussed. The results show that before the strong earthquakes, the high Z_K anomaly value can be generally detected, and it is of practical significance that Z_ (αυ = 0.642) can be uniformly used as the criterion of anomaly. The anomalous values of high Z_K before the strong earthquakes above 7th are generally sustained The short time, the rapid increase, and the large amplitude, the strong earthquakes happened around the maximum value of Z_K.The high Z_K anomalies before the moderate earthquakes lasted for a long time with a gentle change and small anomalies, Year more time.Finally, this paper discusses some other issues, such as the lower limit of magnitude and the influence of the regional range on the value of Z_K.