QUASI-STATIC DEFORMATION ACCOMPANIED BY PRECURSORY CREEP AND POST-SEISMIC FAULT SLIPA MODEL AND SOME OBSERVATION EXAMPLES

In order to set up the relation between fault creeping and crustal deformation in the neighbourhood of it, in this paper, analytical expressions for quasi-static deformation field produced by a slipping f auit of arbitrary dip in a linear viscoelastic half-space are given in closed forms. The forms of slip-time function in the expressions are determined empirically, and the rock media are considered as generalized Kelvins or Maxwell substances. The effect of viscoelasticity on the deformation field has been discussed through numerical computation. By analysing the short period geodetic data obtained in the 1976 Tangshan earthquake region before and after the earthquake, it can be demonstrated that precursory creep had occurred in the upper crust of the epicentral area prior to the main shock and the fault continued to slip after it but the rate fell off exponentially with time. The slip parameters which fit the observed data are estimated and the implication of all these results are briefly discussed.