3-D SUBSURFACE DISPLACEMENT AND STRAIN FIELDS FOR FAULTS AND FAULT ARRAYS IN A LAYERED ELASTIC HALF-SPACE

A quantitative model using elastic dislocation theory has been developed to model the near-field subsurface displacement field associated with faults and fault arrays within an elastic layer above an elastic half-space. A fault is modelled as a surface across which there is a discontinuity in prescribed displacements. Fault displacements may be oblique as well as dip-slip. The mathematical expressions for the surface and subsurface displacements are formed using the Thomson-Haskell matrix technique. Faults may intersect the free surface or may be blind. The model has been used to determine the 3-D surface and subsurface displacement fields for a rectangular fault with constant slip and for an elliptical fault on which the slip varies from a point of maximum displacement at the centre to zero displacement at an elliptical tip-line. The 3-D displacement field and associated strain tensor may be determined for individual slip events on a fault or for cumulative fault displacements. Displacement contour maps may be constructed for either originally horizontal, vertical or inclined horizons. The model has also been applied to multiple fault arrays.