Nonlinear Dynamics of Faulting: Physical Modeling Results

摘要

Under the terms of nonlinear geodynamics developed by Yu.M. Pushcharovskii since the early 1990s, the lithosphere and all of its structural elements are open and nonequilibrium dynamic systems. Various nonlinear effects, whose scale is commensurable with those of the structures and processes bringing them forth, accompany their evolution. Among the wide spectrum of lithospheric structural elements, fault zones are the most convenient for studying the physical nature of nonlinear effects. The dissimilarly directed external forces acting on the deformation process are traditionally attracted to explain the nonlinear character of structure formation. The results of physical modeling, which simulate the structural evolution of an extension zone in a vis-coelastic-ductile model of lithosphere, are reported in this paper. The evolutionary dynamics of extension zones is regarded as a synergetic process that proceeds with consecutive changes of structural levels, each of which has characteristic structural elements and deformational mechanisms. The critical role of transition from one level to another belongs to a particular state of the within-fault fracture systems related to their self-organization that arises spontaneously under nonequilibrium conditions. The fracture systems in this state are especially sensitive to external deformational impact and show a nonlinear response to it. In this case, the nonlinearity is an internal functional property of the system, and not a result of variation in external factors influencing the deformation. A new approach for identification of nonuniformly scaled self-organization is proposed, based on variable information entropy and fractal dimension.