【摘要】 中强地震大多发生在活动断裂带上,研究这些地震带的应力状态及其带上所发生地震的时空特征,对于探索大地震前的前兆信息是非常重要的。分析1970年以来,华北6级以上地震前地震区内的地震活动,发现在震前2-3年,中小地震的空间分布有向地震带内集中的趋势,而在临震前1-2个季度,又表现为向带外发散。这种在震前地震活动分布向条带内集中和发散的趋势为地震预报提供了一定的信息。更多还原

【Abstract】 Most of moderate strong shocks occur in active fault belt. It is important to stu- dy stress state of these seismic belt and temporal-spatial characteristic of earthquakes in the belt for exploring precursor information before large shock. Based on analysis of seismicity in seismic area before M≥6 earthquake in North China since 1970, it is shown that spatial distribution of moderate and micro-earthquakes trends to converge- nce towards the belt in 2 - 3 years before large shocks, and diverge outward belt in 1 - 2 seasons before shock. The tendency provides some information for earthquake prediction更多还原