华北地震活动中短期异常图像研究

系统研究了多种地震活动性方法后认为，1970年以来华北地区发生的Ms≥5．8中强震前，约83％具有3级或4级地震异常条带、孕震空区及信号震出现。震前有信号震的比例占92％，83％的信号震距主震150km以内，距主震发生时间小于1年的占67％。条带时间形成进程在2年内的约占90％，震前条带形成后到主震发生83％在5个月内。空区形成进程在1年半内的占83％，空区形成后到主震发生91％在50天内，为有意义的地震活动图像短期异常特征。文中还探讨了异常条带图像的定量判别指标及其与未来强震的关联。

Study on the medium-and short-term anomaly pattern of seismic activity in North China

After studying different kinds of earthquake activities systematically, we have found that about 83% of the anomalous seismic bands, seismogenic gaps and signal earthquakes with magnitudes 3 or 4 appeared at the same time before moderately strong earthquakes (ML36) since 1970 in North China. 92% of earthquakes were followed signal earthquakes, and 83% of these signal earthquakes are within distance of 150 km from the main earthquakes and 67% of which were followed by main earthquakes occurred in less than a year. 90% of seismic bands formed in two years, and 83% of main earthquake occurred in 5 months after the formation of seismic bands. 83% of seismic gaps formed in a year and half and 91% of main earthquakes occurred in 50 days after the formation of seismic gaps. These characteristic are very significant short-term anomaly features of seismic activity pattern. We also discussed the relationship between quantitative discriminant index of anomalous band pattern and the future strong earthquakes, which is practicable in earthquake prediction.