Abstract The wellwaterlevel system is a natural body strain gauge. Taking the theoretical earth tide value of body strain as the input of the system and digital observations of well level of the system as the output, the harmonic analysis results of the digital observation of well level computed with Venidikov’s harmonic analysis method is transfer function(sensitivity) of the well level system. The paper takes the amplitude factor of wave M2 as the theoretical calibration value η of well level system.The waterlevel shock wave excited by Wenchuan s8.0 earthquake is calculated by use of the minute values of water level of five wells in May,2008. Meanwhile, the Rayleigh wave data including the maximum amplitude of radial and vertical displacement and its periods,are recorded by seismograph.Body strain wave excited by Wenchuan earthquake is calculated with displacement divergence formula. The result is the volume strain from seismograph which is high frequency is ten times bigger than the one from wellwaterlevel system which is low frequency.The difference between them is discussed at last.
