ANNUAL PERIODIC VARIATIONS CAUSED BY THE CHANGE OF TEMPERATURE IN GEODETIC DISPLACEMENT MEASUREMENTS ACROSS FAULTS

This paper gives first the annual periodic variations in the geodetic data obtained from several observation stations for fault displacements in the Beijing region. Then, a two-dimensional non-linear finite element scheme is used to simulate the annual periodic variations caused by the change of temperature in the data of the displacement measurements across faults. The strains obtained from computation agree roughly with field measurements. The results indicate that for inhomogenous crustal medium, change of ground temperature can cause sufficiently a variety of complex observed phenomena. For examples, there are two kinds of baselines, one lengthens while the other shortens as the ground temperature rises; there are two kinds of leveling variations, the side of fault of large coefficient of thermal expanson rises as the ground temperature increases or conversely; and so on. However crustal media, in general, are inhomogenous, therefore temperature influence on displacement measurements across faults, should not be ignored.