Abstract: An analysis has been made of the 2005 earth tide observation data recorded by the CZB-1 type perpendicular pendulum tiltmeter at the Yanshou Seismic Station of Heilongjiang,using the two day(48h)and two-day sliding monthly harmonic analysis method.Values of the tidal factor γ and the phase-delay factor Δφ before the Jul 25^th,2005 M_S 5.1 Lindian,Heilongjiang and the Sept 19^th 2005 M_S 4.7 Yakeshi,Inner Mongolia earthquakes have been determined for the semidiurnal constituent(M₂)of the tilt earth tides.As a result,some features of deformation of tide variations prior to some moderate earthquakes have been revealed.Relation expression was preliminarily calculated between the waiting time after anomaly or anomaly amplitude or epicentral distance and earthquake magnitude.Results of comprehensive analysis are as follows:(1)The tidal factor reflects the elastic stage of earth crust media response to tidal force in physical meaning.The earth crust media state varies and the earth crust deformation turns into an instable phase along with stress strengthening before moderate-strong earthquake.Adopting the harmonic analysis method and with a proper calculation length,the anomaly information of the tidal factor and the phase-delay factor are extracted for better analyzing and calculating the stress-strain state of earth crust media against the time series,giving prominence to the short-impending anomaly information,and catching the precursor anomaly of earthquake occurrence.(2)Tidal factor variations reflect the stress change in earth crust media of seismic source area,which offers the short-impending precursor information relating to time.The variation process can be summarized as trend background → augmentation or contraction → extreme → restitution → waiting → earthquake occurrence.(3)The harmonic analysis method of tide has high anti-interference ability.It can remove the interferences,such as the long-term trend drift and environmental effect,to provide stable figures and give prominence to the anomaly information.In addition,the Venedikov harmonic analysis method is a valid method for studying the relationship between the tidal tilt anomalies and the moderately strong earthquake.

Key words: moderate strong earthquake, tilt earth tide, short-impending anomaly

摘要： 选择黑龙江省延寿地震台CZB-1型竖直摆倾斜仪2005年的固体潮观测资料,提取了2005年7月25日黑龙江省林甸M5.1和9月19日内蒙古牙克石M4.7地震前,倾斜固体潮半日波(M₂)的潮汐因子γ及相位滞后因子Δφ等参量,综合分析了中强地震前区域倾斜形变潮汐的短临变化特征。认为:1)对潮汐频段参数潮汐因子、相位滞后因子异常信息进行提取,有利于捕捉地震前兆异常。2)潮汐因子的变化特征从时间上给出了震源的短临前兆信息。从图形变化看,这种变化过程可归纳为趋势性背景变化→增大(或减小)→极值→恢复→等待→发震。3)固体潮调和分析方法具有较强的抗干扰能力,图形变化稳定、异常突出明显。

关键词: 中强地震, 倾斜形变潮汐, 短临异常