ANALYSIS ON EARTH STRAIN TIDE OF GUZA SEISMIC STATION
Xuan Liu · Chinese Journal of Geophysics · 1994
Because the value and direction of principal strain and shear strain of earth strain tide on an arbitrary point of the ground surface can't be measured directly,they can only be obtained indirectly. And the problem mentioned above has not been reported yet in the present documents home and abroad, We systematically give the calculating method which can be used to calculate the value and direction of principal strain and shear strain by using the strain tide observation in more than three different directions, Using this method, we also obtain the value and direction of principal strain and the pictogram of shear strain at Guza station. In order to check the calculating method and computer program, we have used theoretical value of the strain tide in three directions to calculate the shear strain,then on the basis of the value and direction of the principal strain,compute shear strain.The calculation results,show that the shear strain value obtained indirectly is nearly the same as the theoretical value of the shear strain calculated directly from the theoretical formula of erath shear strain tide and there exists slight difference between them on the places of the decimal point (unit 10-9).At last we have discussed the importance of the value and direction of the principal strain and shear strain in earthquake prediction and the study of geologic structure.