STATIC DEFORMATION OF A UNIFORM HALF-SPACE DUE TO A LONG DIP-SLIP FAULT

Closed-form expressions for the displacements and stresses at an arbitrary point of a homogeneous, isotropic, perfectly elastic half-space caused by a dip-slip line source obtained earlier are integrated analytically to derive the elastic residual field due to a long dip-slip fault of finite width. The results are valid for an arbitrary dip of the fault and for arbitrary receiver locations inside the medium. The variation of the displacement and stress field with the distance from the fault is studied numerically. Contour maps showing the stress field around a long dip-slip fault are obtained. Permanent surface deformations which occur as a result of faulting can be measured from geodetic surveys carried out before and after an earthquake. These observations can be used to obtain the fault parameters (dip, slip, width, depth) by inversion, using the theoretical expressions given in the paper. The features of the observational data which are diagnostic of the source properties are: the asymmetry of the data; the magnitude of various components of deformation; and the rate of fall of these components with distance. The asymmetry depends mainly on the dip, the magnitude on the slip and the rate of fall on the depth of the fault.