The Critical Point Theory of Earthquakes: Observation of Correlated and Cooperative Behavior on Earthquake Fault Systems

Chen, C - National Central University, Department of Earth Sciences, Taipei, 320 Taiwan
Rundle, J B - University of California, Center for Computational Science, Davis, CA 95161 United States
Li, H - National Central University, Department of Earth Sciences, Taipei, 320 Taiwan
Holliday, J R - University of California, Center for Computational Science, Davis, CA 95161 United States
Turcotte, D L - University of California, Center for Computational Science, Davis, CA 95161 United States
Klein, W - Boston University, Department of Physics, Boston, MA 02215
United States
Tiampo, K F - University of Western Ontario, Department of Earth Sciences, London, ON N6A 5B7 Canada

The scaling properties of earthquake populations, for instance, show remarkable similarities to those observed among the critical phenomena of magnetic or other composite systems in statistical physics. Fluctuations associated with correlations in space and time are inherent in critical phenomena. Laboratory observations demonstrate the existence of very large spatial and temporal fluctuations in the density of the liquid-vapor mixture near the critical point, and in the magnetization of ferromagnets near the Curie point. Observations also indicate that these fluctuations are correlated over distance and time scales that can be characterized by correlation lengths and the correlation times, respectively. Since earthquakes represent a release of accumulated stress, the critical point theory of earthquakes would therefore predict that main shock and its aftershocks would be associated with a strongly correlated spatial region of high stress that forms prior to the main shock. Indirect evidence for the existence of such correlated regions of high stress has been reported, for example in the appearance of time- dependent variations in the form of the Gutenberg-Richter magnitude frequency relation, the Omori aftershock relation, and in the apparent correlation in seismic activity over large distances. In the critical point model, main shocks, their foreshocks and aftershocks are all associated with the formation of a correlated, cooperative spatial region with high stress. Until now, only indirect evidence of the existence of these correlated regions has been reported. Here in this paper we present observations and analyses that allow us to directly map the high stress, spatially correlated regions preceding four major earthquakes, i.e. the 1992 Landers (California), 1995 Kobe (Japan), 1999 Chi-Chi (Taiwan) and 1999 Hector Mine (California) earthquakes. We therefore conclude that the locations and extent of large main shocks and their immediate aftershocks can be determined from seismicity data taken prior to the main shocks, and provide additional evidence in support of the critical point theory for earthquakes.