Abstract: In this paper, the authors take the borehole bulk strain as an example to correct borehole bulk strain data by tidal factor. The result shows that the coefficient of every strain is different because of the difference of the station structural condition, topographic condition and borehole condition. The coefficient is relatively stable with time, variation factor is about 4.1% at most and 0.1% at least, indicating that the result of the correction is quite well. This paper presents the coefficients of some observational data of borehole bulk strain stations. The method has the advantages in easy calculating, dependable result, practically using and so on.

Key words: Borehole strainmeter, Tidal factor, Correction, Variation factor, Earthquake field