HR: 15:10h
AN: S43D-07    [Abstracts]
TI: Why Weibull?
AU: * Newman, W
EM: win@ucla.edu
AF: Departments of Earth and Space Sciences, Physics and Astronomy, and Mathematics, University of California, Los Angeles, CA 90095 United States
AU: Turcotte, D L
EM: turcotte@geology.ucdavis.edu
AF: Department of Geology, University of California, One Shields Ave., Davis, CA 95616 United States
AU: Shcherbakov, R
EM: roshch@cse.ucdavis.edu
AF: Center for Computational Science and Engineering, University of California, One Shields Ave., Davis, CA 95616 United States
AU: Rundle, J B
EM: rundle@cse.ucdavis.edu
AF: Center for Computational Science and Engineering, University of California, One Shields Ave., Davis, CA 95616 United States
AB: The statistical distribution of recurrence times of characteristic earthquakes plays an important role in hazard assessment. Assumed distributions include the exponential (random), Weibull (stretched exponential), log-normal, and Brownian passage time (inverse Gaussian). In this paper we argue that the Weibull distribution provides the proper scaling. This distribution has found wide applicability in statistical physics. In this paper we present the results of numerical simulations using a hybrid model that combines the forest-fire model with the site-percolation model in order to better understand the earthquake cycle. We consider a square array of sites. At each time step, a "tree" is dropped on a randomly chosen site and is planted if the site is unoccupied. When a cluster of "trees" spans the site (a percolating cluster), all the trees in the cluster are removed ("burned") in a "fire". The removal of the cluster is analogous to a characteristic earthquake and planting "trees" is analogous to increasing the regional stress. We find that the statistical distribution of recurrence times (number of time steps between model earthquakes) is in much better agreement with the Weibull distribution than either the log-normal or Brownian passage time distributions. The coefficient of variation (aperiodicity) of the distribution is 0.394. We also show that the synthetic distribution of recurrence times obtained using the "Virtual California" model is in excellent agreement with the Weibull distribution. For the Parkfield section the simulated earthquakes have a coefficient of variation with a value 0.354. The actual earthquakes on the Parfield section are in good agreement with the Weibull distribution with a coefficient of variation with a value 0.378.
DE: 0515 Cellular automata
DE: 0545 Modeling (4255)
DE: 4430 Complex systems
DE: 7223 Earthquake interaction, forecasting, and prediction (1217, 1242)
DE: 7230 Seismicity and tectonics (1207, 1217, 1240, 1242)
SC: Seismology [S]
MN: Fall Meeting 2005