Stress accumulation during the aseismic period in a seismically active regions becomes a subject of research during the last few decades. Mathematical modelling has been formulated to study the nature of stress accumulation during this quasi static aseismic period. In the present case a rectangular strike slip fault of finite length has been taken to be situated in a linearly viscoelastic half space representing the Lithosphere-Asthenosphere system. The model consist of the properties of both the Maxwell and the Kelvin (Voigt) type material. Analytical expressions for displacement, stresses and strain have been formulated and computational work with suitable model parameters have been carried out. A details study of these expressions may be useful in formulating an effective earthquake prediction programme.