关键词: 中短期地震前兆, 区域特征, 华东地区

Abstract: Based on analysis of seismicity pattern evolution and precursor field evolution prior to major earthquakes in East China in recent 30 yeas, regional characteristics of the medium -and short -term earthquake precursors in the region have been emphatically studied in this paper. The results show that the medium - and short-term stag e in earthquake preparing process exists objectively and can be recognized. The main indices for the transitional period from the medium-term stage to the medium- and short-term stage of the preparation process are as follow s: ① Abrupt increase of the number of regional swarms (more than 3 swarms in a year with M_L ≥ 3. 0); ② Occurrence of the significant imminent earthquakes; ③ Appearance of dynamic seismic activity belt (or dynamic seismic gap) ; ④ Appearance of group precursory anomalies; ⑤ Appearance of dynamic changes of seismicity parameters. Based on the results mentioned above we have builta medium - and short-term prediction index system and method with good prediction effect in East China. Finally, the general applicability of the medium - and short-term earthquake precursors and the issue regarding prediction of future strong earthquakes site have been discussed.

Key words: Medium-and short-term earthquake precursors, Regional features, East China