A conceptually simple model, consisting of a network of particles and springs, is used to model dynamic fracturing processes. In this model, the springs provide the resistance to compression and deformation, and particle masses provide the inertial effect. When such a network is subjected to a dynamic loading, Newton's equations of motion are solved to determine the evolution of the network. If a spring is stretched or compressed beyond prescribed threshold limits at any time-step, the spring breaks and initiates a fracture. The model results indicate that the fracture pattern depends on the inhomogeneities of the rock, the active crack-driving force, and the in-situ stresses. ¿ American Geophysical Union 1992