HR: 0830h
AN: NG41C-0074    [PDF]
TI: The role of heterogeneities as a tuning parameter of earthquake dynamics in relation to criticality
AU: * Zoeller, G
EM: zoeller@rz.uni-potsdam.de
AF: Institute of Physics and Institute of Mathematics, University of Potsdam POB 60 15 53, Potsdam, 14415 Germany
AU: Holschneider, M
EM: hols@math.uni-potsdam.de
AF: Institute of Mathematics, University of Potsdam POB 60 15 53, Potsdam, 14415 Germany
AU: Ben-Zion, Y
AF: Department of Earth Sciences, University of Southern California, Los Angeles, CA 90089-0740 United States
AB: We investigate the influence of spatial heterogeneities on various aspects of seismicity in a single-fault model. The model dynamics is governed by realistic boundary conditions consisting of constant velocity motion of regions around the fault, static/kinetic friction laws, creep with depth-dependent coefficients as in Ben-Zion (JGR 101, 1996), and 3D elastic stress transfer based on the solution of Chinnery (1963). The dynamic rupture is approximated on a continuous time scale using a finite stress propagation velocity (``quasi-dynamic model''). The model produces a ``brittle-ductile'' transition at a depth of about 12.5 km, realistic hypocenter distributions, and other features of seismicity compatible with observations. Ben-Zion et al. (JGR 108, 2003) suggested that the range of size scales in the distribution of strength-stress heterogeneities acts as a tuning parameter of dynamics, and that the evolution of this parameter in large earthquake cycles produces intermittent criticality. Here we test this hypothesis by performing a systematic parameter-space study with different forms of heterogeneities. In particular, we analyse spatial heterogeneities that can be tuned by a single parameter in two distributions: (1) a set of circular asperities with a different stress drop and variable range of radii and (2) spatial heterogeneities with fractal properties and variable fractal dimension. We analyze the influence of the tuning parameter of the heterogeneities on different measures of seismicity and discuss the results in terms of the phase diagram approach of Dahmen et al. (Phys. Rev. E 58, 1998).
DE: 3210 Modeling
DE: 3220 Nonlinear dynamics
DE: 7209 Earthquake dynamics and mechanics
DE: 7260 Theory and modeling
SC: Nonlinear Geophysics [NG]
MN: 2003 Fall Meeting