The paper investigates the stresses around a fault or crack in dissimilar media. It extends the analysis of symmetrical or antisymmetrical loading of an isotropic homogeneous plate with a crack to the case where the crack separates two different isotropic homogeneous regions. The stress singularities remain proportional to the inverse square root of the distance from the crack, but the stresses exhibit an oscillatory character of the form $ r^{-\frac{1}{2}}\sin(b\log r) $, confined near the crack. A shear stress along the material interface exists when the materials are different. The study extends a previous plane-stress problem to the case of a crack between two dissimilar materials. The geometry considered is that of two materials, $ M_1 $ in the upper half-plane and $ M_2 $ in the lower half-plane, joined along the x-axis. The elastic plane stress solution is sought for unloaded edges along the negative x-axis. In the homogeneous case where $ M_1 = M_2 $, the stresses near the crack base become infinite according to an inverse square-root law. The paper then considers the case of dissimilar materials, leading to complex eigenvalues for the stress function. The solution involves a biharmonic stress function $ \chi(r, \psi) $ that satisfies certain boundary conditions. The homogeneous case results in eigenvalues $ \lambda = (2n+1)/2 $, with the lowest value $ \lambda_{min} = 1/2 $, leading to stress behavior $ \sigma \sim r^{-1/2} $. For the bimaterial case, complex eigenvalues are found, leading to oscillatory stress behavior of the form $ \sigma \sim r^{-1/2} \sin(\lambda_j \log r) $, which is similar to the homogeneous case. The paper concludes that the stress behavior near the crack base is dominated by the lowest eigenvalue, and that the stress singularities are similar to the homogeneous case. The results are consistent with the qualitative observations of high strain energy release near the fault. The study also shows that the maximum energy release areas reported by St. Amand are in agreement with the calculated results.The paper investigates the stresses around a fault or crack in dissimilar media. It extends the analysis of symmetrical or antisymmetrical loading of an isotropic homogeneous plate with a crack to the case where the crack separates two different isotropic homogeneous regions. The stress singularities remain proportional to the inverse square root of the distance from the crack, but the stresses exhibit an oscillatory character of the form $ r^{-\frac{1}{2}}\sin(b\log r) $, confined near the crack. A shear stress along the material interface exists when the materials are different. The study extends a previous plane-stress problem to the case of a crack between two dissimilar materials. The geometry considered is that of two materials, $ M_1 $ in the upper half-plane and $ M_2 $ in the lower half-plane, joined along the x-axis. The elastic plane stress solution is sought for unloaded edges along the negative x-axis. In the homogeneous case where $ M_1 = M_2 $, the stresses near the crack base become infinite according to an inverse square-root law. The paper then considers the case of dissimilar materials, leading to complex eigenvalues for the stress function. The solution involves a biharmonic stress function $ \chi(r, \psi) $ that satisfies certain boundary conditions. The homogeneous case results in eigenvalues $ \lambda = (2n+1)/2 $, with the lowest value $ \lambda_{min} = 1/2 $, leading to stress behavior $ \sigma \sim r^{-1/2} $. For the bimaterial case, complex eigenvalues are found, leading to oscillatory stress behavior of the form $ \sigma \sim r^{-1/2} \sin(\lambda_j \log r) $, which is similar to the homogeneous case. The paper concludes that the stress behavior near the crack base is dominated by the lowest eigenvalue, and that the stress singularities are similar to the homogeneous case. The results are consistent with the qualitative observations of high strain energy release near the fault. The study also shows that the maximum energy release areas reported by St. Amand are in agreement with the calculated results.