A multilayer model of time dependent deformation following an earthquake on a strike slip fault

A multilayer half‐space model of the earth is used in finite element calculations of time dependent deformation and stress following an earthquake on an infinitely long strike slip fault. The model involves shear properties of an elastic upper lithosphere, a standard viscoelastic linear solid lower lithosphere, a Maxwell viscoelastic asthenosphere, and an elastic mesosphere. Time dependent displacements, strains, and stresses are computed both at the surface of the earth and at depth. The analysis includes both systematic variations of fault and layer depths and comparisons with simpler elastic lithosphere over viscoelastic asthenosphere calculations. For conditions which may be appropriate for the earth, the creep of both the lower lithosphere and the asthenosphere can contribute to the postseismic deformation. The magnitude of the deformation is enhanced by a short distance between the bottom of the fault (slip zone)and the top of the creep layer but is less sensitive to the thickness of the creeping layer. Furthermore postseismic restressing is increased as the lower lithosphere becomes more viscoelastic, but the tendency for the width of the restressed zone to grow with time is retarded.