Positive feedback, memory, and the predictability of earthquakes

C. G. Sammis*,† and
D. Sornette‡,§

^*Department of Earth Sciences, University of Southern California, Los Angeles, CA 90089-0740; ^‡Institute of Geophysics and Planetary Physics, and Department of Earth and Space Science, University of California, Los Angeles, CA 90095; and^§ Laboratoire de Physique de la Matière Condensée, Centre National de la Recherche Scientifique Unité Mixte de Recherche 6622, and Université des Sciences, B.P. 70, Parc Valrose, 06108 Nice Cedex 2, France

Abstract

We review the “critical point” concept for large earthquakes and enlarge it in the framework of so-called “finite-time singularities.” The singular behavior associated with accelerated seismic release is shown to result from a positive feedback of the seismic activity on its release rate. The most important mechanisms for such positive feedback are presented. We solve analytically a simple model of geometrical positive feedback in which the stress shadow cast by the last large earthquake is progressively fragmented by the increasing tectonic stress.

Footnotes

↵ † To whom reprint requests should be addressed. E-mail: sammis{at}usc.edu.
This paper results from the Arthur M. Sackler Colloquium of the National Academy of Sciences, “Self-Organized Complexity in the Physical, Biological, and Social Sciences,” held March 23–24, 2001, at the Arnold and Mabel Beckman Center of the National Academies of Science and Engineering in Irvine, CA.
Abbreviations:
1. SOC, self-organized criticality
2. LURR, Load/Unload Response Ratio