Abstract: A series of processing of the data obtained from the hourly-measured water levels as well asthe data of the atmosphere-pressure and the earth tide was made. The triangular-pressure fittingwas used to rule out the effect of the annual perieds.Following taking both the factors of the atmosphere-pressure related water levels and the remaining errors of the mean square errors of thewater level rasiduals as an index for the short-term prediction of earthquakes, it has been improved to refine the precursory anomalies of the water level．The concept of“entrophy”has beenadopted to make a relativety objective evaluation of these parameters under question.The effective precusory anomalies may be up to 0．65 and 0. 59,suggesting it is better representative of theprecusory infomation of earthquakes.

Key words: Water level-atmosphere pressure factor, Residual error, Beijing, Water level related short-term prediction

摘要： 对塔院井3年水位、气压、固体的逐时值进行一系列数据处理,并用三角多项式拟合以消除年周期影响,把水位日气压系数和水位残差日均方差的余差作为塔院井短临预报指标,改进了水位前兆异常的提取方法。同时用熵的概念对这两个参数做出较客观的评价,计算出它们的前兆效益水平分别达到0.65和0.59,说明其较好的反映了地震的前兆信息。

关键词: 水位气压系数, 水位残差均方差, 北京, 水位短临预报