Abstract: This paper has mainly studied the 14 earthquakes with M>5 in the Eastern China since 1970s. The results show that, no matter the anomaly that is judged by anomaly start-time or that is by anomaly turning-ttime, there is a certain relation between the spatial distribution of precursors and seismicity before earthquakes, and 3-stages feature of different characteristics of precursor anomalies. If the start time of anomaly is taken as criterion, the frequency of precursor anomalies reflects the middle-term information of seismic generating process. If the time of turning point or ending time of the deformation abnormities is taken as the judge criterion, the frequency of precursor abnormities reflects the short-term information. Based on the above-mentioned study, we develop a method named the anomaly-turning ratio (TAR). The results show that, the high-value anomaly of the TAR exceeding mean value may reflect the short-term information. By theoretical analysis, we provide a comprehensive method to judge the variety from middle-term anomaly to short-term one in the Eastern China.

Key words: Earthquake precursor, Short-term anomaly, East China region