首都圈地区中等地震前小震活动异常特征分析

Analysis on the characteristic of seismicity anomalies before medium earthquakes in Capial Zone

近年来首都圈地区以中等地震活动为主,本文用反映地震频度、能量、平均震级的基本参量如频度、缺震、断层总面积、地震活动度等研究该区中等地震前的活动性异常特征,发现这些异常对1999～2001年首都圈地区的中等地震有较好的对应关系,当同时出现三项低值异常后,有震预报准确率较高。这些方法对首都圈地区中等地震的短期预测有重要作用,2001年12月28日滦县ML4.2级地震就是用该方法在震前做了较成功的预测。由于参量指标与地震间的映震效果具有一定的阶段性和区域性,需要用发展变化的眼光,时刻跟踪并不断调整改进所使用的参量指标,才能更好地捕获地震信息。

the earthquake activity is mainly medium events in Capital zone in recent years.The characteristic of seismicity anomalies before medium earthquakes is studied with the parameters that reflect frequency,energy,mean magnitude,such as frequency,earthquake deficiency,total area of fault plane and degree of seismicity.It is found that most of the anomalies have good correspondence with the medium events in Capital Zone from 1999 to 2001,and the accuracy is high when 3 low value anomalies appear.This method is effective in the prediction in Capital Zone,such as the prediction of Luanxian M4.2 earthquake occurred on Dec.28,2001.Since the effect of parameters' index that reflects earthquakes has some phasic change and regionality,we need adjust the indexes continuously to capture more seimic information.