Mathematical modeling on the Karkheh reservoir stresses and its application to the Dalpari fault

In this research, a new mathematical modeling on strength changes due to reservoir elastic stresses across the preexisting fault plane is introduced. The method has been applied to the Dalpari fault, which is one of the potential seismic sources in the vicinity of the Karkheh reservoir. In this method the distribution of total stress across the fault cannot be determined because the initial stress is unknown; the pore pressure due to the reservoir is also not considered. The mathematical modeling method has been explained briefly in the following. The lake first is divided into small rectangles of sides a and b by two sets of orthogonal straight lines, one set conveniently east-west and the other north-south. The mean water depth h in each rectangle with area S is estimated, and the water pressure on the floor of the rectangle is replaced by a vertical force F =? gS h at the center of rectangle. It is clear that rather smaller rectangles lead to more precise modeling, hence, each rectangle with increasing h is divided into some parts. The water pressure of the lake is simulated by a set of point forces F which applied in the -X3 direction and acting on the rectangles. We define now a mathematical model of the single force F in the elastostatic fields using the delta function conception