华北地区第三、 四活动期平静幕后期中强地震活动与未来强震

本文通过分析、 研究华北地区第三、 四活动期各平静幕后期的中强地震活动特征, 认为: ① 华北地区第三、 四活动期9个活跃幕中有7个在首发强震前3年内发生中强地震, 其中第四活动期1～4活跃幕首发强震前2年内都发生了中强地震, 未来第5活跃幕首发强震前, 以发生中强地震作为序幕的可能性较大; ② 华北地区平静幕后期的中强地震活动, 对其后活跃幕首发强震在时间和地点上有一定指示作用。 由于华北地区可能即将进入新的强震活跃幕, 该研究对判断华北地区未来强震趋势具有实用意义。

Moderate-strong Seismicities in Later Stage of Seismic Quiescence Epeisodes of 3rd and 4th Seismically Active Periods and Future Strong Shock in North China

In this paper,we analysed and studied moderate-strong seismic characteristics in the 3rd and 4th seismically active periods in North China and proposed that: ① Seven active episodes in nine of the 3rd and 4th seismically active periods in North China have the same character that moderate-strong earthquakes occurred three years before the first strong shock and two years before for the 1st to 4th active episodes of the 4th seismically active period espically, so it will be more propably to have moderate-strong earthquake as prelude before the first strong shock in the coming 5th active episode; ② The moderate-strong seismicities in the later stage of seismic quiescence episodes in North China have certain indication in time and location to the first strong shock in the following active episode. It may proceed in a new strong-shock active episode in North China, so this study will be useful for strong earthquake trendency prediction in North China.