【摘要】 以 1 998年 1月 1 0日张北 M6.2级地震为例 ,分析了地震前宽城短水准、兴隆短水准和易县短水准异常的特征。短水准资料具有年变周期 ,分析异常必须剔除年变。本文应用周期滤波方法对短水准资料进行了处理 ,发现短水准异常地震前有明显的阶段性 ,异常发展可分为初期、中期、临震三个阶段 ,且具有明显的由中期向短临转化标志。更多还原

【Abstract】 Based on Zhangbei earthquake occurred on Jan.1,1998,the character of fixed leveling anomalies observed in Kuancheng,Xinglong and Yixian Seismostation are analyzed.As the data of fixed leveling have annual period,so we must eliminate its annual variation before analyzing its anomaly.After processed with periodical filtering method we find fixed leveling anomalies have different phases in development,which can be divided into early term,medium term and imminent term three stages,and it has distinct sign turning from medium term into imminent term.更多还原