【摘要】 使用１９７２—１９９２年期间华北地区的地震资料进行地震空间集中度Ｃ值、地震危险度Ｄ值的空间扫描，研究它们在华北地区中强以上地震前的短期异常变化。结果表明大体于震前半年左右的短期阶段，Ｃ值与Ｄ值中期异常区存在三类不同形态的变化，其中大部分震例的Ｃ值或Ｄ值中期异常区出现明显的缩小乃至消失，本文将这一特征作为短期异常的标志；第二类表现为它们的中期异常区未出现明显的变化；第三类表现为其中期异常区出现明显扩大。文中还讨论了Ｃ值、Ｄ值用于短期地震预报的方法和预报效果等有关问题。更多还原

【Abstract】 he seismic data recorded in 1972-1992 in North China are used to spatial scanning of seismic concentration degree C-value and seismic dangerous degree D-value in this paper. The anomalous variations in short term before moderate-strong earthquakes are studied. The results show that there are three kinds of variations with different shapes in mid-term anomaly zones of C-value and D-value half year before the event. Most of earthquake cases show that the obvious contraction or disappearance may exist in the mid-term anomaly zone, which can be taken as the mark of short term anomaly; the second kind does not show obvious variation in the mid-term anomaly zone; and the third kind appears obvious enlargement in the mid-term anomaly zone. Prediction method of short term using C-value and D-value, and prediction effect are also discussed in this paper.更多还原