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The aim of the present paper is to obtain the two-dimensional deformation of a two-phase elastic medium consisting of half-spaces of different ri- gidities in welded contact due to a buried long strike-slip fault. The solution is valid for arbitrary values of the fault-depth and the dip angle. The effect of fault-depth on the displacement and stress fields for different values of dip angle has been studied numerically. It is found that the displacement field varies significantly for a buried fault from the corresponding displacement field for an interface-breaking fault. The contour maps showing the stress field for various dip angles for buried and interface-breaking fault have been plotted. It has been observed that the stress field varies significantly for a buried fault from the corresponding stress field for an interface-breaking fault.

The elastic residual field due to a strike-slip fault in various Earth models has been calculated by several investigators e.g. [1-12] and others. In [

The purpose of present paper is to obtain an analytical solution for the deformation of a long strike-slip fault buried at arbitrary depth located in an elastic, homogeneous, isotropic half-space welded with another elastic, isotropic half-space. The depth occurs explicitly in the solution. Therefore, the effect of the variations in the depth for a fixed dip and vice-versa can be studied directly.

Let the Cartesian co-ordinates be denoted by with -axis vertically downwards. Consider a two-phase elastic medium consisting of halfspaces welded along the plane. The upper halfspace is called Medium I and the lower halfspace is called Medium II with rigidities, respectively. A long inclined strike-slip fault with strike along -axis is situated in the lower halfspace. The upper edge of the fault is taken to be at depth d (

Under the assumption of antiplane strain case, the displacement components are of the form

For zero body forces, the equilibrium equations reduces to

The displacement field due to a long inclined strikeslip line dislocation parallel to x_{1}-axis and passing through the point (y_{2}, y_{3}) in the lower half-space (medium II) is given by [

where

= displacement discontinuity (slip)

ds = width of the line dislocation

= dip angle

= receiver location

= source location

We write (

where d is depth of the upper edge A of the fault and s is the distance from the upper edge of the fault measured in the down-dip direction. Inserting the values of y_{2} and y_{3} from Equation (6) into Equations (3) and (4) and integrating over s between the limits (0, L), we obtain the following expressions for the displacements in the two half-spaces due to an inclined strike-slip fault of finite width L and infinite length:

where

The non-zero stresses at any point of a two-phase elastic medium are given by

From Equations (7) and (8) and Equation (10), we get the following expressions for the stresses. For the medium I,

and the medium II,

where now

Equations (7) and (8) and Equations (11)-(14) give the elastic residual field at any point of two half-spaces due to a long strike-slip fault of finite width dipping at an angle buried at depth d. On taking d = 0, the results for an interface breaking fault located in the lower halfspace welded with another half-space coincide with the corresponding results of [

We have studied the behaviour of the parallel displacements and the stresses numerically.

In all these figures, there is a discontinuity at = X cot. Figures 4(a)-(d) show the variation of with for different value of d for when the observer is in the upper half-space.

The contour maps for the shear stress have been plotted in Figures 5(a) and (b) for an interface breaking fault located in the lower half-space welded with another half-space for and 45˚. Solid lines indicate positive values and dashed lines negative values.

The values are shown in units of. Heavy line denotes the fault. The shear stress is discontinuous at the interface.

Figures 6(a) and (b) are for the buried strike-slip fault d = L for and 45˚, respectively. The contour maps for the shear stress are shown in Figures 7(a) and (b) for interface-breaking fault d = 0 for and 45˚. The stress is continuous at the interface. The values are shown in units of. Figures 8(a) and (b) are for the buried fault d = L.

The results presented in this paper are significant

for obtaining the deformation due to an inclined strikeslip fault located at an arbitrary depth and arbitrary dip angles. In the earlier paper [

One of the authors SR is thankful to University Grant Commission, New Delhi for financial support in the form of Major Research Project.