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1984年3月30日21时22分以后,徐州应变观测台(含站)的各类倾斜仪、应变仪因地点而异,自北向南,陆续记录到周期约10分钟,持续80分钟左右的波动,振幅为10~(-8)～10~(-9)(弧度或应变单位)。经研究,这种同步的异常变化不是地震前兆,而是气压干扰所致。本文从理论上计算了大风(风压)干扰量,对倾斜是5×10~(-13)弧度,估算的体应变和线应变为10~(-12)～10~(-13)量级。用锥形气压负荷模型计算了1.6毫巴气压波动所带来的近地表倾斜和应变,约为10~(-8)～10~(-9)量级,与实际结果比较接近。计算结果还表明,气压波动所产生的应变和倾斜随深度衰减很慢。从而看出,包括较深的钻孔型仪器及深水井在内,欲避免气压微变化干扰很难,只宜用高精度的气压观测资料来校正。
After 21:22 on March 30, 1984, all kinds of inclinometers and strain gauges in Xuzhou Strain Observatory (including stations) varied from place to place. From north to south, they recorded the periods of about 10 minutes and continued for about 80 minutes Fluctuation, amplitude of 10 -8 (-8) ~ 10 -9 (radians or strain units). After the study, this synchronous abnormal change is not a seismic precursor, but due to atmospheric pressure interference. In this paper, the gale (air pressure) interference is calculated theoretically. For slant is 5 × 10 ~ (-13) radian, the estimated body strain and linear strain are on the order of 10 ~ (-12) ~ 10 ~ (-13) . The near-surface tilt and strain caused by 1.6 mbar atmospheric pressure fluctuations were calculated by using the cone-shaped barometric pressure model, which was about 10 -8 to 10 -9, which was close to the actual result. The calculation also shows that the strain and slope caused by the pressure fluctuations are very slow with depth. Thus, including deeper borehole instruments and deep wells, it is difficult to avoid interference with slight changes in atmospheric pressure. Only high-precision atmospheric pressure observation data should be used for correction.