2 nd Chaotic Modeling and Simulation International Conference, 15 June 2009, Chania Crete Greece Modeling and Simulation of SelfOrganized Criticality in Landslides Markos Avlonitis 1 and George Efremidis 2 1 Department of Informatics, Ionian University, Platia Tsirigoti 7, GR – 49100 Corfu, Greece, Email: avlon@ionio.gr 2 Sector of Geotechnical Engineering, Department of Civil Engineering University of Thessaly, Pedion Areos, GR – 38334 Volos, Greece, Email: gefraim@civ.uth.gr Abstract: The paper elaborates on an avalanchelike dynamic model for catastrophic landslides introducing the effect of water diffusion along the failure plane. The main idea lies on the assumption that the stochastic nature of water diffusion along the failure plane results in a dynamic decrease in time of the shear strength for the entire rock mass parallel to this plane. To this end, a single stochastic constitutive equation is proposed, modeling external and internal stresses, spatial interactions between neighborhood sites as well as water diffusion, which are shown to reproduce correctly experimental observations. Indeed, simulations of a discrete automaton were performed, in order to study the model dynamics. It is demonstrated that the model exhibits features of selforganized critical behavior and solves the reported discrepancy between simulations outcomes and experimental data for the corresponding power law exponent. Keywords: Catastrophic landslides, Water diffusion, Discrete automaton, SelfOrganized Criticality. 1. Introduction Landslide is the movement of a mass of rock or debris down a slope, which has one or more distinct failure surfaces. In this paper catastrophic landslides on a discrete failure plane are considered. Their velocities are typically on the order of 1m/day up to 300 Km/hr (when they are generated by earthquakes). Landslide activity increases after prolonged rains, or after the frost leaves the ground in the spring. Landscape evolution arises from the integrated effect of erosion and mass transfer over geological spatial and temporal scales, as well as from the effect of water presence into the rock mass. Concerning the ground water, the most important effect in a rock mass is the reduction in stability resulting from water pressures within the discontinuities. The landslides are related with the perturbation of mass balance of rock mass, and they are caused by natural reason (i.e. earthquake, intense rainfall), gradual attenuation of mechanic properties of the rock mass, or even human intervention (i.e. excavations). The dimensions of landslides are exceptionally various. In general, they are largescale movements with