中等地震活动增强作为强震标志的研究

通过对(1990~1996年)发生在我国大陆及边境地区24次6级以上地震的分析研究表明,80%的强震主震前在震源区及附近有中等地震活动增强的过程。异常表现出共同的基本特征,即长期平静→增强活动→震前平静→发震。震前平静至发震大约经历几个月到2年时间(平均10个月左右),可以作为中短期地震预报判据。用岩石蠕变声发射实验来解释这一现象,可把中等地震活动增强看作是稳态蠕变阶段后期发生的广义前震。

Taking the enhancementof moderate earthquakes as an index for future strong earthquakes

24 earthquake with M≥6.0 occurred in China 's mainland from 1990 to 1996 are analyzed. The research results show that before about 80% of the strong earthquakes, the activity of earthquakes became active within and near the epicentral area. The anomaly is expressed in similar process,i.e., from a long-term quiescence, to moderate earthquake enhancement then a second quiescence just before strong shock, and finally the main shock occurs. The period from the quiescence just before strong shock till the earthquake occurrence is usually about several months to 2 years, with 10 months on average, which can be used as an index to judge whether the seismogenic process has been into the middleterm to imminent term for earthquake prediction. According to the acoustic emission experiments, the enhancement of the moderate seismicity could be taken as generalized foreshocks occurred at the end of the stable creep stage.